hplc exemple

REV. CHIM. (Bucureti) 58 Nr. 1 2007


Validarea unei metode HPLC de determinarea atenololului n plasma uman

LAURIAN VLASE1, SORIN LEUCUA1, SILVIA IMRE21 Universitatea de Medicin i Farmacie Iuliu Haieganu, Facultatea de Farmacie, Cluj-Napoca, Str. Victor Babe, Nr. 41, 400012,Cluj, Romnia2 Universitatea de Medicin i Farmacie Trgu-Mure, Facultatea de Farmacie, Str. Gheorghe Marinescu, Nr. 38, 540139,Trgu-Mure, Romnia

An HPLC method with fluorescence detection for atenolol determination in human plasma was developedand validated, using metoclopramide as internal standard. After protein precipitation with perchloric acid,atenolol was separated at 30 C on a C18 column, 150 mm x 4.6 mm, 5 m. The mobile phases consisted ofa mixture of acetonitrile:sodium dihydrogen phosphate 40 mM, pH 3 with phosphoric acid 85%, 10:90 (solventA), and acetonitrile (solvent B). The elution was made in gradient mode: 0-4 min 0%B, 4-8 min 30% B, 8-13min 0%B, at 1 ml/min. The excitation and emission wavelengths were Ex/Em = 235/ 315 nm for 7.5 min, and309/356 until 13 min. The method was linear between 10-1000 ng/ml, with an accuracy and precision of -8.66.3 %, being between -18.7% and 9.8% at lower limit of quantification. The method was applied foratenolol determination in human plasma after oral administration of 100 mg atenolol.

Keywords: atenolol, HPLC, plasma, metoclopramide

Atenololul este un beta-blocant selectiv fr activitateintrinsec, utilizat n tratamentul hipertensiunii, angineipectorale sau a aritmiilor cardiace. Dup administrareaoral, absorbia este redus datorit caracterului suhidrofil, numai 50% din doz fiind biodisponibil. Dup odoz oral de 100 mg, maximul concentraiei plasmaticeeste atins la 3 ore i este, n medie, de 0,5 g/mL. Existvariaii mari n ceea ce privete mrimea picului plasmatical atenololului datorit diferenelor n metabolizare [1,18].

Dezvoltarea unei metode de determinare a concen-traiei plasmatice a unei substane medicamentoase nscopul aplicrii acesteia n studii de farmacocinetic ibioechivalen trebuie s in cont de cteva aspecte.Metoda trebuie s demonstreze, pe lng acuratee iprecizie pe domeniul de concentraii investigat, specifi-citate, n raport cu compuii endogeni plasmatici i cei demetabolizare, i suficient sensibilitate, aa nct s permitcuantificarea analitului dup cel puin patru timpi denjumtire pentru a se putea realiza analiza farma-cocinetic [23-24]. Nu trebuie neglijat nici faptul c acestestudii implic analiza a sute sau mii de probe i, nconsecin, este de preferat o metod rapid i economicde prelucrare a probelor i, pe ct posibil, un timp scurt deanaliz instrumental.

innd cont de aceste aspecte, n lucrare esteprezentat o nou metod HPLC de determinare cantitativa atenololului n plasma uman, aplicnd un procedeu

* email [email protected]

simplu i economic de prelucrare a probelor bazat peprecipitarea proteinelor i folosind ca standard internmetoclopramida (fig. 1).

Partea experimentalMateriale de lucru

S-au utilizat atenolol i metoclopramid clorhidrat,standarde de lucru oferite de SC Terapia S.A., Romnia.Acetonitrilul, metanolul, fosfatul diacid de sodiu, acidfosforic 85%, acid percloric 70% au fost de calitate MerckKgaA (Darmstadt, Germania). Apa deionizat a fostobinut cu ajutorul sistemul de purificare a apei DirectQ5 (Millipore SA, Molsheim, Frana).

Condiii cromatograficeCromatograful utilizat a fost tipul 1100 Series (Agilent

Technologies, SUA), fiind compus dintr-o pomp binar,injector automat, termostat, fixat la 30C i detector defluorescen (lungimile de und de excitaie i emisie Ex/Em = 235/ 315 nm pn la 7,5 min, 309/356 pn la 13 min).Separarea s-a realizat pe o coloan cromatografic de tipulZorbax SB-C18, 150 mm x 4.6 mm i.d., 5 m (Agilent). Fazamobil a fost format dintr-un amestec A ce conineacetonitril:fosfat diacid de sodiu 40 mM, adus la pH 3 cuH3PO4 85%, n raport volumetric 10:90, i solventul Bacetonitril. Eluia s-a fcut n gradient de compoziie: 0-4min 0%B, 4-8 min 30% B, 8-13 min 0%B. Debitul fazei mobilea fost 1 mL/min. nainte de analiz, faza mobil a fostdegazat pentru 10 min n baia de ultrasunete ElmaTranssonic 700/H (Singen, Germania). Volumul de injectarea fost 100 L.

Soluii standardSoluiile stoc de atenolol i metoclopramid (1 mg/mL)

au fost obinute prin dizolvarea substanelor n metanol ipstrate la 4C, fiind stabile cel puin 3 luni n aceste condiii.Soluiile standard de lucru de atenolol i metoclopramidau fost obinute prin diluarea corespunztoare a soluiilor

Fig. 1. Structurile chimice ale (a) atenololului i (b) metoclopramidei

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stoc cu ap distilat, fiind utilizate la marcarea a 0,5 mLplasm pentru a obine concentraii plasmatice pedomeniul 10-1000 ng/mL atenolol i 500 ng/mLmetoclopramid.

Prelucrarea probelorntr-un tub de centrifug de 2 mL s-au introdus: 0,5 mL

plasm, 100 L ap distilat i 100 L soluie standardintern (2,5 g/mL). Tubul a fost agitat 10 s la vortex-mixer(Genie 2, Scientific Industries Inc., SUA). S-au adugat 200L soluie acid percloric 7%. Dup agitare, tubul a fostcentrifugat la 6000 rpm timp de 4 min. 200 L dinsupernatant s-au adus ntr-un flacon de injectare.

Validarea metodei analiticeOrice metod analitic, n particular o metod

bioanalitic, pentru a fi validat trebuie s demonstreze nprimul rnd c este specific n raport cu substaneleendogene existente n matricea biologic, cu produii demetabolizare i reactivii utilizai la pregtirea probei [23-24]. n acest sens s-a verificat specificitatea metodeifolosind ase plasme blanc din surse diferite, urmrindu-se dac exist interferene plasmatice endogene la timpiide retenie ai analiilor studiai. De asemenea, s-au analizatase probe de plasm uman recoltate la diferii timpi dupadministrarea oral a 100 mg atenolol.

Linearitatea metodei s-a verificat prin metoda celor maimici ptrate, pe domeniul 10-1000 ng/mL atenolol, alegndcalibrarea cu standard intern ca model de calibrare.Raportul dintre aria atenololului i aria metoclopramiduluia fost calculat pentru apte nivele de concentraieplasmatice ale atenololului n domeniul ales i utilizatpentru construirea curbelor de calibrare. S-a investigatdistribuia rezidualilor, deviaia relativ procentual aconcentraiei recalculate din ecuaia curbei de calibrarefa de concentraia realizat, pentru fiecare punct decalibrare. Modelul de calibrare a fost considerat corect alesdac rezidualii s-au ncadrat ntre limitele 20% la limitainferioar de calibrare i 15% la celelalte concentraii inu au avut o tendin continu de cretere sau scdere cuconcentraia. Corelaia s-a apreciat liniar la o valoare acoeficientului de determinare mai mare de 0,99.

Acurateea, exprimat ca deviaia relativ procentuala concentraiei msurate fa de concentraia realizat, iprecizia metodei, exprimat prin deviaia standard relativprocentual sau coeficientul de variaie CV%, s-audeterminat la trei nivele de concentraie, 50,2, 251,1 i,

respectiv, 803,5 ng/mL, aflate n domeniul de concentraiiales. Au fost determinate precizia i acurateea n aceeaizi de determinri, pe baza a cinci msurtori pe cinci probediferite la fiecare concentraie, i acurateea i precizia nzile diferite pe baza analizei n zile diferite a cte cinci probestandard la fiecare din cele trei nivele de concentraiealese.

Limita de cuantificare inferioar s-a apreciat ca cea maimic concentraie de pe dreapta de calibrare cu o acurateei precizie n limitele 20%.

Regsirea a fost apreciat la patru nivele deconcentraie, inclusiv la limita inferioar de cuantificare,prin compararea rspunsului atenololului obinut dupprecipitarea proteinelor cu cel obinut cu o soluie standardde aceeai concentraie n ap i prelucrat n acelai modca probele biologice.

Aplicaie clinicMetoda cromatografic validat a fost aplicat ntr-un

studiu de bioechivalen a dou produse farmaceutice careconin 100 mg atenolol. Timpii de recoltare a probelorbiologice au fost 0, 0,5, 1, 1,5, 2, 2,5, 3, 4, 6, 8, 10, 12, 24 oredup administrarea dozei. Dup centrifugarea sngelui,plasma separat a fost separat i ngheat sub -20 C pnla prelucrare. n timpul analizei probelor biologice provenitede la voluntari, s-a verificat validitatea metodei incluzndn fiecare serie de analiz un numr de probe standard decontrol n duplicat la trei nivele de concentraie (50,2; 251,1i, respectiv, 803,5 ng/mL). Seriile de analiz s-au consideratvalide dac patru din ase probe standard de control auavut concentraiile n limitele 15% din valoarea nominal.Dou din ase probe standard de control, dar nu la aceeaiconcentraie, pot avea concentraiile n afara acestor limite.

Rezultate i discuiiLungimile de und de lucru au fost stabilite la valorile

Ex/Em 235/315 nm pentru atenolol i 309/356 nm pentrumetoclopramid, innd cont de diferenele spectraledintre cele dou substane i urmrind obinerea unuimaxim de selectivitate i sensibilitate (fig. 2).

Aa cum se observ din figura 3, n condiiilecromatografice propuse nu exist interferene la timpii deretenie ai analiilor, atenololul i metoclopramida fiindseparai de compuii endogeni n 13,5 min de analiz.

Metoda prezint un rspuns liniar pe domeniul 10 1000ng/mL, cu un coeficient mediu de determinare R2 > 0,999.

Fig. 2 Spectrele de excitaie (a) i emisie (b) aleatenololului ATN i metoclopramidei MTC

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Distribuia rezidualilor a fost ntmpltoare, ncadrndu-se ntre limitele -8,7% i 7,1%, la limita inferioar decuantificare acetia fiind ntre limitele 20%. Modelul decalibrare a fost acceptat.

Acurateea i precizia determinrilor efectuate naceeai zi (tabelul 1) i n zile diferite (tabelul 2) sunt maimici dect valorile admise n astfel de determinri (20%la limita de cuantificare, respectiv, 15% la celelalteconcentraii). Limita de cuantificare a fost stabilit la 10ng/mL atenolol, cu o acuratee i precizie n limitele admisede 20%.

n condiiile propuse, regsirea atenololului s-a ncadratntre limitele 101-116%.

n ceea ce privete analiza probelor biologice, toateseriile de analiz au fost validate, cel mult dou din aseprobe standard de control au fost n afara limitelor admise,dar nu ambele la aceeai concentraie. n figura 4 esteprezentat curba de variaie concentraie timp la unvoluntar sntos, dup administrarea oral a unei dozeorale unice de 100 mg atenolol.

Fig. 3 Cromatogramele pentru (a) un blanc deplasm i (b) o prob plasmatic cu atenolol

ATN i metoclopramid MTC (250 ng/mLatenolol, 500 ng/mL metoclopramid)

Tabelul 1ACURATEEA, PRECIZIA I REGSIREA N ACEEAI ZI (n = 5)

Tabelul 2ACURATEEA, PRECIZIA I REGSIREA NTRE ZILE DIFERITE (n = 5)

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Tabelul 3CARACTERISTICI ALE UNOR METODE DE CROMATOGRAFIE DE LICHIDE DE NALT PERFORMAN

APLICATE LA DETERMINAREA ATENOLULUI N SNGE, SER SAU PLASM, PUBLICATEN LITERATURA DE SPECIALITATE

Fig. 4. Concentraiile plasmatice ale atenololului la un voluntar dupadministrarea pe cale oral a unei doze unice de 100 mg atenolol

Numrul de articole tiinifice referitoare la deter-minarea cantitativ a atenololului n plasm, snge sau ser,prin cromatografie de lichide de nalt performan estemare. Studiind articolele prezentate succint n tabelul 3,se poate constata c majoritatea metodelor propuse sebazeaz pe extracia lichid-lichid a atenololului din probelebiologice [3-5,7,11-14,18,21-22], o metod consumatoarede solveni i timp, dar cu o limit inferioar de cuantificare

n jur de 10 ng/ml, mai bun dect n celelalte cazuri ncare s-a utilizat extracia n faz solid [1,8-10,21]. Deimetodele bazate pe injectare direct de plasm, extraciei concentrare automat n faz solid, au demonstrat osensibilitate bun [6,16-17,19-20], necesit completareasistemului cromatografic cu un dispozitiv special deextracie.

Metoda propus n aceast lucrare se bazeaz pe analizaatenololului prin cromatografie de lichide de naltperforman cu detecie de fluorescen, dup precipitareasimpl a proteinelor cu acid percloric. Prin alegereajudicioas a lungimilor de und de excitaie i emisie s-aputut realiza o analiz specific i sensibil a atenololului,cu o limit de cuantificare de 10 ng/mL, comparabil cucea prezentat n majoritatea metodelor citate, iar timpul

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de analiz stabilit asigur eluia tuturor interferenilorplasmatici. De fapt, ntr-o singur lucrare dintre celestudiate este descris o limit inferioar de cuantificaremai bun [3].

ConcluziiA fost optimizat i validat o metod HPLC cu detecie

fluorimetric pentru cuantificarea atenololului n plasmauman. Dei aceast metod are o sensibilitate


comparabil cu cea raportat n alte lucrri, avantajulacesteia l constituie faptul c modul de prelucrare aprobelor de plasma este foarte simplu, bazndu-se pesimpla precipitare a proteinelor. innd cont de lucrriletiinifice studiate, acest mod de prelucrare a probelorplasmatice de atenolol nu a mai fost descris pn acumi, n condiiile cromatografice propuse, prezint cel puinaceeai sensibilitate ca metodele descrise n literaturbazate pe extracie lichid-lichid sau extracie n faz solid.Metoda i-a demonstrat validitatea n timpul analizeiprobelor de plasm obinute n cadrul unui studiu debioechivalen.

Bibliografie1.*** Physicians Desk Reference, 47th edition, Medical EconomicsData, 1993, p. 11292.VERGHESE, C., MCLEOD. A., SHAND. D., J. Chromatogr., 275, 1983,p. 3673.MILLER, L.G., GREENBLATT, D.J., J. Chromatogr. B, 381, 1986, p. 201.4.ROSSEEL, M.T., VERMEULEN, A.M., BELPAIRE, F.M., J. Chromatogr.,568, 1991, p. 2395.MILLER, R.B., GUERTIN, Y., J. Liq. Chromatogr., 15, 1992, p. 12896.HE, J., SHIBUKAWA, A., NAGAKAWA, T., WADA, H., FUJIMA, H., IMAI,E., GO-OH, Y., Chem. Pharm. Bull., 41, nr. 3, 1993, p. 5447.EGGINGER. G., LINDNER, W., KAHR, S., STOSCHITZKY, K., Chirality,5, nr. 7, 1993, p. 5058.PHELPS, S.J., ALPERT, B.S., WARD, J.L., PIEPER, J.A., LIMA, J.J., J.Clin. Pharmacol., 35, 1995, p. 2689.CHATTERJEE, D.J., LI, W.Y., HURST, A.K., KODA, R.T., J. Liq.Chromatogr., 18, 1995, p.791

10.LUKKARI, P., SIREN, H., J. Chromatogr. A, 717, 1995, p. 21111.IRSHAID, Y.M., RAWASHDEH, N.M., AWWADI, F.F., KATO, M.K., Int.J. Clin. Pharmacol. Ther., 30., nr. 10, 1996, p. 45712.MARTINS, M.L., PIEROSSI, M.A., MORAES, L.A., RIBEIRO, W., ABBIB,E.JR., MENDES, G.B., POLI, A., DE NUCCI, G., MUSCARA, M.N., Int. J.Clin. Pharmacol. Ther., 35, nr. 8, 1997, p. 32413.GIACHETTI, C., TENCONI, A., CANALI, S., ZANOLO, G., J. Chromatogr.B, 698, 1997, p. 18714.GAILLARD, Y., PEPIN, G., J. Chromatogr. A, 763, 1997, p. 14915.CHIU, F.C.K., ZHANG, J.N., LI, R.C., RAYMOND, K., J. Chromatogr. B,691, 1997, p. 47316.HERMANSSON, J., GRAHN, A., HERMANSSON, I., J. Chromatogr. A,797, 1998, p. 25117.CHIAP, P., HUBERT, PH., BOULANGER, B., CROMMEN, J., Anal. Chim.Acta, 391, 1999, p. 22718.NIOPAS, I., DAFTSIOS, A.C., XANTHAKIS, I., NIKOLAIDIS, N., NJAU,S.N., Arzneim.-Forsch./Drug Res., 50 (I), nr. 3, 2000, p. 24319.CHIAP, P., MIRALLES BURAGLIA, B., CECCATO, A., HUBERT, PH.,CROMMEN, J., J. Chromatogr. B. Biomed. Sci. Appl., 739, 2000, p. 20520.MISLANOVA, C., HUTTA, M., J. Chromatogr. B, 765, 2001, p. 16721.IHA, M.H., MARTINEZ, A.S., BONATO, P.S., J. Chromatogr. B, 767,2002, p. 122.DELAMOYE, M., DUVERNEUIL, C., PARAIRE, F., DE MAZANCOURT,P., ALVAREZ, J.C., Forensic Sci. Int., 141, nr. 1, 2004, p. 2323.*** U.S. Department of Health and Human Services, Food and DrugAdministration, Guidance for Industry Bioanalytical Method Validation,May 200124.*** The European Agency for the Evaluation of Medicinal Products,Note for Guidance on the Investigation of Bioavailability andBioequivalence, 26 July 2001

Intrat n redacie: 9.07.2006

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Determination of Salicin Content of Some Salix L.Species by HPLC Method

AYEGL GVEN1*, OKAN ARIHAN2 , M. LEVENT ALTUN3, ERDAL DIN4, DUMITRU BLEANU5,61 Ankara University, Faculty of Pharmacy, Department of Pharmaceutical Botany, 06100 Tandogan-Ankara, Turkey2 Yznc Yil University, Faculty of Art and Science, Department of Biology, Van, Turkey3 Ankara University, Faculty of Pharmacy, Department of Pharmacognosy, 06100 Tandogan-Ankara, Turkey4 Ankara University, Faculty of Pharmacy, Department of Analitycal Chemistry, 06100 Tandogan-Ankara, Turkey5 ankaya University Department of Mathematics and Computer Sciences, Faculty of Arts and Sciences, 06530 Balgat,Ankara, Turkey6 National Institute for Laser, Plasma and Radiation Physics, Institute of Space Sciences, Mgurele-Bucharest, P.O. Box, MG-23,R 76911, Romania

In this paper, we find the salicin content of the nine species of Salix L from the province of Ankara, Turkey,namely Salix triandra, S. alba, S. excelsa, S. fragilis, S. babylonica, S. caprea, S. cinerea, S. pseudomedemiiand S. amplexicaulis. A simple HPLC method was applied to the determination of Salicin of these ninespecies in barks and leaves of female and male. Chromatographic separation was carried out by a mobilephase consisting of bidistilled water, tetrahydrofuran and ortho-phosphoric acid (97.7: 1.8: 0.5) (v/v/v). Thesalicin amount of these samples was analyzed by measuring the peak area at the wavelength, 270 nm. Areversed phase phenyl column (250 x 4.6mm, 5m) was used and flow rate was set to 1 ml/min. in anisocratic elution. The results provided by HPLC method was found in agreement with those indicated byEuropean Pharmacopoeia. It was observed that S. babylonica female bark sample possess the highestsalicin content (2.675), while S. caprea female bark (0.058) has the lowest salicin content as w/w (%).

Keywords: Salix, willow, salicin, HPLC method

Willow (Salix L.) species belong to the family Salicaceaeincluding deciduous and dioecious trees and bushesinhabiting wetlands or humid areas and comprising 500species all over the world [1]. 28 species of willows wererecorded in Turkey, two taxa of them are endemic in Turkey[2,3,4]. In traditional medicine, the barks of willows areused for rheumatism, anti-pyretic, and pain reliever inTurkey [5]. Phenolic glycosides are commonly found assecondary metabolites of willows containing 1.5-11 %salicin and its derivatives [6, 7]. Within the Salix genus,these compounds have been used as taxonomic markers[6]. Willow bark is official in the European, German andBritish Herbal Pharmacopoeia [7, 9]. The Commission Emonograph recommends liquid and solid preparations forinternal use with an average daily dosage correspondingto 60-120 mg total salicin, which is equivalent to 6-12 g driedbark. Willow bark is used for diseases accompanied byfever, rheumatic ailments and headaches [7]. Dailyconsumption of Salicis cortex extract with 240 mg salicinper day affects platelet aggregation to a far lesser extentthan acetylsalicylate. Both a lesser bleeding time and lowerside drug effects were observed during treatment withwillow bark extract [10]. A recent study proved that orallyadministered salicin produces antipyretic action withoutcausing gastric injury [11]. Willow bark also has antioxidantactivity mainly because of its phenolic compounds [12].

Although Turkey has a rich willow population with its28 Salix species, there is no study about the salicin contentof the barks and leaves of male and female specimens ofwillow species. This study fills this gap of information aboutthis important medicinal plant growing in Ankaras region.

The proposed HPLC method is different from thatproposed in [9]. Therefore, the method was optimizedaccording to the experimental conditions in our laboratory.In this context, the proposed HPLC method was

successfully applied to the determination of salicin contentof the nine species of Salix L. in the province of Ankara,Turkey.

Experimental partChemicals

Salicin (Merck-107665) used as the standard chemicalwas obtained from Merck Chemicals. Chromatographicgrade-double distilled water, HPLC grade methanol (Merck106018), HPLC grade tetrahydrofuran (Merck 108101) andHPLC grade ortho-phosphoric acid (Merck 100565) wereused.

Plant MaterialPlant materials were collected from various localities in

the province of Ankara. During the collection of materials;bark and leaf samples for all species were takenconsidering both male and female specimens. Plantmaterials were dried in a cool and shad medium. Voucherspecimens are prepared and stored at AEF (AnkaraUniversity, Faculty of Pharmacy Herbarium). Localities ofthe investigated plant samples are given in table 1.

Extraction1.25 g of dried powdered material was macerated two

times with 75 mL and finally 50 mL of methanol for 2.5 hat room temperature. The extracts were combined, thenfiltered and evaporated to dryness under a temperaturenot exceeding 40C.

The residue was dissolved with 50 mL of HPLC gradeMerck methanol. Solution was passed through a 0.45 mfilter and 20 L extract was directly injected into the HPLC.The results were obtained as a mean value of threeseparate injections.

* email: [email protected]


ApparatusThe method was performed with a LC system consisting

of a Hewlett Packard Series 1100 model. UV-VIS detectorwas set at 270 nm and peak areas were integratedautomatically by computer using Agilent softwareprogramme. Separation was carried out using a reversephase phenyl column (250 x 4.6mm, 5m) and flow ratewas set to 1ml/min. in an isocratic elution.

All the calculations concerning the quantitative analysiswere performed with external standardization bymeasurement of peak areas.

Standard SolutionsStock solution (25 mg/25 mL) of salicin was prepared

in the mobile phase consisting of bidistilled water,tetrahydrofuran and ortho-phosphoric acid (97.7: 1.8: 0.5)(v/v/v). Standard series in the concentration range of 100-1000 /mL were obtained from the stock solution. Themobile as a solvent was used for all HPLC experimentalstudies.

Chromatographic conditionsHPLC analysis was performed by isocratic elution with

flow rate 1 ml/min which is a modification presented inEuropean Pharmacopeia [9]. The mobile phasecomposition consists of bidistilled water, tetrahydrofuranand ortho-phosphoric acid (97.7: 1.8: 0.5) (v/v/v). Allsolvents were filtered through a 0.45 m Millipore filterbefore being used and degassed in an ultrasonic bath.Volumes of 20 L extracts prepared from each sample were

injected into the column. Quantification was realized bymeasuring the peak area at the wavelength 270 nm.

Results and DiscussionThe determination of salicin according to gender and

organs of 9 willow trees was performed. In Turkey, Salixspecies are grouped under two main categories: subgenusSalix (S. triandra, S. alba, S. excelsa, S. fragilis, S.babylonica) and subgenus Vetrix (S. caprea, S. cinerea, S.pseudomedemii, S. amplexicaulis). The outline of thedeveloped HPLC and its chromatographic conditions forthe determination of salicin in the above samples wasexplained in the following sections.

Method developmentIn our study, several chromatographic conditions were

tested for the separation and determination of salicin insamples. Good separation and determination of nine Salixspecies in barks and leaves of female and male wereperformed by using the mobile phase consisting ofbidistilled water, tetrahydrofuran and ortho-phosphoricacid (97.7: 1.8: 0.5) (v/v/v) and phenyl column (250 x4.6mm, 5m), at flow rate of 1 mL/min. Chromatogramswere plotted by UV-VIS detector at the wavelength of 270nm. Detector responses were measured as peak areas.The injection volume was 20 g/mL and triplicate injectionswere used for each sample. At the flow rate of 1 mL/minthe retention time was 8.44 min for salicin and sample asshown in figure1A and B, respectively.

Table 1LOCALITIES OF THE INVESTIGATED SALIX SPECIES

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Standard series in the concentration range of 100-1000g/mL salicin was prepared in the mobile phase.Calibration graph was obtained by using the relationshipbetween concentration and peak areas. Linear regressionanalysis and its statistical results were summarized in table2.

Method validationIn optimized chromatographic conditions, the validation

of HPLC procedure was carried out by using themonograph of the International Conference onHarmonization (ICH) [17]. The linearity of HPLC detectorresponse for the determination of salicin at 270 nm wasobserved in the working concentration range of 100-1000g/mL at the five different concentration levels. Analysisof each concentration was repeated three times. Eachconcentration was repeated three times and a pice ofinformation on the variation in the peak area betweensamples having the same concentration was obtained. Thelinearity of the calibration functions of salicin at the workingwavelength was confirmed by looking at the high value ofthe correlation coefficient (table 2). For this HPLC method,a linear regression function is represented in table 2.

The precision of HPLC procedure was tested by fivereplicate determinations at different concentration levels.Relative standard deviation was found to be 1.36 % as it isshown in table 3. The accuracy of the proposed HPLCmethod was tested by analyzing synthetic samples atdifferent concentration levels. The mean recovery valuewas found 100.4 % (table 3).

A good agreement between the analysis results wasobserved for HPLC method. During the analysis procedure,the interference and the systematical error were notobserved.

In accordance with ICH [17], the limit of detection (LOD)and the quantitation (LOQ) were calculated by using thestandard deviation of the response and the slope of thelinear regression line (table 2).

The calibration range, according to salicin concentrationpresented in Salix species was designated in the practicalrange to give an accurate, precise and linear response.

The matrix effect in samples, nine Salix species, wasstudied for the proposed HPLC method. We observed thematrix effect does not give any error for the determinations.

Time (min)0 2 4 6 8 10 12 14 16

mAU

0

255075

100125150 VWD1 A, Wavelength=270 nm175

Salicin (standard)

mAU

0

20

40

60

80

100 VWD1 A, Wavelength=270 nm

Time (min)0 2 4 6 8 10 12 14 16

Salicin (sample)

A)

B)

Fig. 1. Chromatograms of A) 100 mg/mL standard and B) sample (Salix babylonica female bark)

Table 2LINEAR REGRESSION ANALYSIS AND ITS STATISTICAL RESULTS

10


Salicin analysisThe proposed HPLC were applied to the determination

of salicin in the barks and leaves of male and female innine Salix (Salix triandra, S. alba, S. excelsa, S. fragilis, S.babylonica, S. caprea, S. cinerea, S. pseudomedemii andS. amplexicaulis) . The assay results of nine Salix speciesare shown in table 4. Their percent mean and standarddeviation values are summarized in the same table. Goodagreement was observed for the proposed HPLC approachand literature methods.

It is known that male willows have lower salicin contentthan females [13, 14]. Our results show that salicin contentof female barks and leaves of Subgenus Salix is higher thanthe males. The salicin content of male barks and leaves ofSubgenus Vetrix is higher than the females. Therefore,among all species, the highest salicin content was foundin the S. babylonica female bark (2.675 %) (see Fig. 1B)and the lowest was found at S. caprea female bark (0.058%) (table 4).

Table 4EXPERIMENTAL RESULTS FOR SALICIN CONTENT IN THE BARKS AND LEAVES OF SALIX

SPECIES BY HPLC METHOD

Table 3RECOVERY DATA OBTAINED BY APPLYING HPLC METHOD TO SYNTHETIC SAMPLES

There was no previous study for comparison of maleand female Salix cinerea bark and leaf specimens however,the period for the collection of the specimens in this studywas not suitable for gender identification. The salicincontent was determined also for those samples (table 4).As it is well known, the salicin amount is related withharvest times, seasonal variations, locality, gender and ageof the plant and the part of the bark harvested as well asspecies with diversity [15].

The results of our study and the findings in literature arefairly comparable with those presented in [16]. Especiallyfor Salix caprea, the results are exactly the same. Thecomparisons are not possible for S. cinerea, S.pseudomedemii and S. amplexicaulis since no recordswere found in literature.

11


ConclusionsIn this study, an HPLC method was developed and

applied to the determination of salicin content of the ninespecies of Salix L. in Ankara region, Turkey. We observedthat the proposed HPLC approach gave us successfullyassay results for the analysis of salicin in all samples. Theexperimental results for S amplexicaulis was found in goodaggrement with those prepsented by EuropeanPharmacopoeia [9].

This paper is the first study of the analysis of salicin inwillow species growing in Turkey done according to theirgender and organs. The results of this current work form abasis for the future studies in this field.

AcknowledgmentsThis study was supported by grants from the Research Foundation ofAnkara University (Grant No. 2001-08-03-033).

References1. HEYWOOD, V. H. ,Flowering Plants of the World, Oxford UniversityPress. London. 1979, p. 1172. DAVIS, P.H., Flora of Turkey and the East Aegean Islands, 7, EdinburgUniversity Press, Edinburgh, 1970, p. 6943. GNER, A., ZIELINSKI, J., The Karaca Arboretum Magazine, 2 , 1,1993, p.14. GNER, A., ZHATAY, N., EKIM, T., BAER, K.H.C., Flora of Turkeyand the East Aegean Islands, 11. Edinburgh University Press, Edinburgh,2000, p. 5765. BAYTOP, T.,Trkiyede Bitkilerle Tedavi, 2. baski, Nobel Tip KitabevleriLtd. ti.,Istanbul,1999 (in Turkish), p. 340

6. RECIHARDT, P. B., MERKEN, H.M., CLAUSEN, T. P., J. Nat. Prod, 55 ,nr. 7 , 1992, p. 9707. BLUMENTHAL, M., GOLDBERG, A., BRINCKMANN, J., HerbalMedicine Expanded Commission E Monographs, Integrative MedicineCommunications, Newton, 2000, p. 4088. CALIXTO, J. B., BEIRITH, A., FERRIRA, J., SANTOS, A.R.S., FILHO,V.C., YUNES, R.A., Phytother. Res., 14 , 2000, p. 4019. European Pharmacopoeia 2001, fourth edition, Convention on theElaboration of a European Parmacopoeia (European Treaty Series No.50), Strasbourg, 2001, p.213710. KRIVOY, N., PAVLOTZKY, E., CHRUBASIK, S., EISENBERG, E.,BROOK, G., Planta Med., 67 , 2000, p. 20911. AKAO, T., YOSHINO, T., KOBASHI, K., HATTORI, M., Planta Med.,68, nr. 8 , 2002, p. 71412. KAHKNEN, M., HOPIA, A.I., VUORELA, H.J., RAUHA, J., PIHLAJA,T.S. KUJALA, HEINONEN, M., J. Agr. Food. Chem. 47 , 1999, p. 395413. BOECKLEN, W.J., PRICE, W.P., MOPPER, S., Ecology, 71, nr. 2,1990, p. 58114. JULKUNEN-TIITTO, R., J. Chromatpgr. A, 324, 1985, p.12915. ARIHAN, O., Pharmaceutical Botany Research on the Willow (Salix)Species Growing In Ankara Province, Ankara University, Institute of theHealth Sciences , MasterThesis, Ankara, 200316. JULKUNEN-TIITTO, R., Phytochemistry, 25, nr. 3, 1986, p. 66317. *** European Agency for the Evaluation of Medical Products (1996)ICH Topic Q2B Note for Guidance on Validation of AnalyticalProcedures: Methodology GPMP/ICH/28 1/95


12


Adsorbia anionilor fosfat i tiocianatpe argil anionic Mg3Al-HT

EVELINE POPOVICI1*, RODICA PODE2*, ERIKA REISZ2, LAURA COCHECI2, VASILE PODE2, ELENA-MIHAELA SEFTEL11Universitatea Al. I. Cuza Iai, Bvd. Carol I, Nr. 11, 700506 Iai2Universitatea POLITEHNICA Timioara, P-a Victoriei, Nr.2, 300006 Timioara

This paper dealt with sorption equilibrium and kinetics of phosphate and thiocyanate anions in syntheticwastewaters on Mg3Al-HT anionic clay. The sorption of phosphate was well-developed, the results pointedup parameters that characterised the process (maximum sorption capacity and slope of linear part ofLangmuir isotherm), while thiocyanate sorption occurred weakly, the affinity of the studied adsorbent waslower for this anion. The kinetic study showed that the process might be well described (correlationscoefficients of 0.9970 and 0.9961 for phosphate and thiocyanate, respectively) by a first order kinetics in thetwo anions.

Keywords: hydrotalcite, sorption equilibrium, sorption kinetics, phosphate anion, thiocyanate anion

Hidroxizii dublu stratificai (LDHs) reprezint o clas deminerale naturale i/sau sintetice, cunoscute i subdenumirea de argile anionice. Hidrotalcitul are o structurconstituit din straturi de tip brucit ncrcate pozitiv, n carecationii divaleni sunt substituii de cationi trivaleni, ntr-ocoordinare octaedric. Formula general a compuilor tiphidrotalcit este [M(II)1-xM(III)x(OH)2]

x+ (An-x/n) mH2O, ncare M(II) - cationi divaleni (Mg2+, Zn2+, Fe2+, Ni2+, etc.),M(III) - cationi trivaleni (Al3+, Fe3+, Co3+, Cr3+, etc.) i A -anionii din regiunea interstrat (CO3

2-, SO42-, NO3

-, Cl-, etc.),care asigur electroneutralitatea. Distana dintre doustraturi adiacente depinde n principal de natura speciilordin regiunea interstrat ct i de interaciunea lorelectrostatic cu straturile de tip brucit [1].

Cercetrile cu privire la eliminarea poluanilor organicii anorganici din efluenii industriali prin procese de schimbionic i adsorbie sau procese catalitice care foloseschidroxizii dublu stratificai, modificai sau calcinai, ctigun interes tot mai larg [2-12]. n momentul de fa, se puneaccent pe dezvoltarea unor procedee de eliminare a unorpoluani anorganici din ape reziduale prin procese carefolosesc abilitile adsorbante ale argilelor anionice [13-18].

Prezenta lucrare a urmrit studiul echilibrului i cineticiiadsorbiei anionilor fosfat i tiocianat din ape rezidualesintetice, folosind ca material adsorbant argila anionicMg3Al-HT.

Partea experimentalSinteza argilei anionice Mg3Al-HT s-a efectuat prin

metoda coprecipitrii la suprasaturaie joas [4], folosindazotaii corespunztori drept materii prime [6].

Pentru studiul echilibrului procesului de adsorbie aanionilor luai n studiu, o cantitate bine determinat dinhidrotalcitul Mg3Al a fost pus n contact n flacoane dinsticl de 150 mL, cu cte 50 mL soluii coninnd anioniifosfat, respectiv tiocianat, cu concentraii iniiale variabile.Concentraia hidrotalcitului a fost de 1 g/L. pH-ul soluiilor,determinat cu un pH-metru Inolab, a fost ajustat la valoarea7 0,2. Probele au fost meninute sub agitare energic, la

temperatur constant (25 1C) ntr-un termostat tipShaker Bath pn la atingerea echilibrului. Materialul solids-a separat prin centrifugare.

Pentru studiul cinetic al procesului de adsorbie, probeparalele de soluii coninnd anionii studiai i avndaceeai concentraie iniial, au fost puse n contact cucantiti identice de hidrotalcit. Concentraia hidrotalcituluia fost de 1 g/L. Agitarea s-a realizat ntr-un termostat tipShaker Bath, la temperatura constant, de 25 1C. Ladurate de timp bine determinate, soluiile au fost separatede materialul solid prin centrifugare. Soluiile rezultate lacentrifugare au fost analizate.

Concentraia ionului fosfat n soluie a fost determinatspectrofotometric la 450 nm, utiliznd metoda cu vanado-molibdat, folosind un spectrofotometru UV VIS tip VarianCarry 50 [19]. Concentraia anionului tiocianat s-adeterminat de asemenea spectrofotometric, la 475 nm [20].

Rezultate i discuiia. Echilibrul adsorbiei anionilor fosfat i tiocianat pehidrotalcitul Mg3Al.

ntruct din datele experimentale cu privire la adsorbiaanionului fosfat s-a observat c, la limita superioar adomeniului de concentraii de echilibru capacitatea deadsorbie a anionului fosfat pe materialul studiat a rmaspractic constant, pentru interpretarea datelor de echilibrua fost utilizat ntr-o prim etap izoterma Langmuir nforma raional i liniarizat (1) i (2):

eL

eLmaxe CK1

CKqq+

= (1)

maxLmax

e

e

e

qK1

qC

qC

+= (2)

n care:qe cantitatea de anioni adsorbit la echilibru, mg

.g-1;qmax - cantitatea maxim adsorbit, mg

.g-1;Ce - concentraia de echilibru, mg

.L-1;KL constanta de echilibru, L

.mg-1.

13



n tabelul 1 sunt prezentai parametrii caracteristiciizotermei Langmuir precum i valoarea coeficientului decorelare.

are loc cu rezultate bune, evidentiae prin parametrii cecaracterizeaz procesul (valoarea capacitii maxime deadsorbie, panta poriunii liniare a izotermei Langmuir), ntimp ce adsorbia anionului tiocianat decurge mai slab,afinitatea adsorbantului studiat pentru acest anion fiindredus. Rezultatele obinute confirm datele din literatura[12], conform crora afinitatea hidrotalciilor pentru anioniimonovaleni este sczut.

b. Cinetica adsorbiei anionilor fosfat i tiocianat pe argilaanionica Mg3Al-HT.

Din punct de vedere cinetic, att adsorbia anionuluifosfat ct i a anionului tiocianat pe hidrotalcitul studiatpoate fi considerat un proces de ordin I n raport cuanionul, n condiiile n care s-a lucrat cu exces deadsorbant. Relaia care descrie procesul de pseudo-ordinI poate fi exprimat att n funcie de concentraia anionilordin soluie:

tk/ClnC ot = (5)

n care:Ct este concentraia anionului n soluie, la timpul t, mg/L;Co concentraia iniial a anionului n soluie, mg/L;k - constanta de vitez a procesului de pseudo-ordin I,

min-1;t - timpul, minct i n funcie de cantitatea de anioni adsorbit pe

hidrotalcit (ec. tip Lagergren) [12]:

tkq

qqlne

te=

(6)n care:

qe este cantitatea de anioni adsorbit la echilibru, mg/g;qt - cantitatea de anioni adsorbit la timpul t, mg/g;k - constanta de vitez a procesului de pseudo-ordin I,

min-1;t timpul, minn figurile 3 i 4 sunt prezentate curbele cinetice pentru

adsorbia anionilor fosfat i tiocianat pe hidrotalcitul Mg3Al.Din pantele dreptelor obinute au fost calculate

constantele de vitez, ale cror valori sunt prezentate ntabelul 2.

Valorile constantelor de vitez obinute pentru adsorbiaanionilor fosfat i tiocianat au acelai ordin de mrime cudatele din literatur [12].

Tabelul 1PARAMETRII CARACTERISTICI IZOTERMEI LANGMUIR

Veridicitatea utilizrii modelului Langmuir estejustificat de valoarea foarte bun a coeficientului decorelare R, de 0,9991 ct i de faptul c domeniul Henryeste foarte bine definit (fig. 1). Pe de alt parte, prelucrareadatelor de echilibru folosind modelul Langmuir a permiscalcularea prin constanta de echilibru a procesului deadsorbie KL, a energiei Gibbs standard pentru procesulde adsorbie,

o

298adsG

:

Lo

298ads lnKTRG = (3)

n care:R este C constanta general a gazelor, J/mol.K;T - temperatura absolut, K.

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

0 50 100 150 200 250 300 350 4000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

c e / q

e [g/

l]

ce [mg/l]

q e [m

g/g]

ce [mg/l]

Fig. 1. Izoterma Langmuir pentru adsorbia anionului fosfat pehidrotalcitul Mg3Al

Valoarea energiei standard Gibbs, de -22,9 kJ/mol,permite ncadrarea procesului de adsorbie n categoriaadsorbiei fizice [21]. Valoarea maxim a capacitii deadsorbie a anionului fosfat, de 111 mg/g, situeazmaterialul studiat n categoria adsorbanilor potenialutilizabili n procesele de epurare avansat a apelor cuconinut de fosfai.

n figura 2 este prezentat izoterma de adsorbiecaracteristic anionului tiocianat.

Din alura poriunii iniiale a izotermei se constatabsena domeniului Henry, forma de S la concentraii deechilibru mici i prin urmare, slaba afinitate a hidrotalcituluiMg3Al pentru anionul tiocianat. Pe domeniul mediu deconcentraii de echilibru, procesul este bine descris deizoterma Freundlich, a crei form liniarizat este descrisde ecuaia 4:

ee lnClnlnq += (4)

Valoarea maxim a capacitii de adsorbie pe domeniulde concentraii de echilibru atins n studiu a fost de 38mg/g.

Din analiza rezultatelor privind adsorbia celor doi anionipe hidrotalcitul Mg3Al, rezult c adsorbia anionului fosfat

10 20 30 40 50 600

5

10

15

20

25

30

35

40

1.0 1.5 2.0 2.5 3.0 3.5 4.01.0

1.5

2.0

2.5

3.0

3.5

ln q e

ln Ce

q e [m

g/g]

ce [mg/l]

Fig. 2. Izoterma Freundlich pentru adsorbia anionului tiocianat pehidrotalcitul Mg3Al

14


Concluziin lucrare s-a studiat echilibrul i cinetica procesului de

adsorbie a anionilor fosfat i tiocianat pe argila anionicMg3Al-HT.

Pentru interpretarea rezultatelor obinute n cazulanionului fosfat a fost utilizat modelul Langmuir. Utilizareaizotermei Langmuir a fost determinat de faptul c la limitasuperioar a domeniului de concentraii de echilibrucapacitatea de adsorbie a anionului fosfat a rmas practicconstant. Coeficientul de corelare foarte bun, de 0,9991 aconfirmat veridicitatea acestei opiuni. Interpretareadatelor experimentale conform modelului Langmuir apermis i determinarea capacitii maxime de adsorbie aanionului fosfat, care a fost de 111 mg/g. Determinarea pebaza constantei de echilibru Langmuir a energiei standardGibbs a permis ncadrarea procesului de adsorbie studiatn categoria adsorbiei fizice, aspect care nu a fost precizatcu claritate n alte studii.

Din alura poriunii iniiale a izotermei experimentale aanionului tiocianat a reieit absena domeniului Henry islaba afinitate a hidrotalcitulului pentru acest anion.Aceasta a fost evideniat i de valoarea de numai 38 mg/g a capacitii de adsorbie.

Studiul cinetic al adsorbiei a artat c procesul poate fidescris bine (coeficient de corelare de 0,9970 pentruanionul fosfat i respectiv 0,9961 pentru anionul tiocianat)de o cinetic de ordin I n raport cu cei doi anioni. Au fostcalculate constantele de vitez corespunztoare.

Mulumiri: Acest studiu a fost desfurat cu sprijin financiar din parteaAutoritii tiinifice MATNANTECH, n baza proiectului CEEX Nr.1/S1-2005.

Bibliografie1. FORANO, C., Clay Surfaces. Fundamentals and Applications, Elsevier,(Wypych F. and Satynarayana K. G. Eds.), New York, 2004, p. 4262. YU, L., ROTO, R., VILLEMURE, G., n: Abstracts of 43rd Annual Meetingof CMS 4eme Colloque du GFA, June 3-7, France, 2006, p.2633. CHTELET, L., BOTTERO, J. Y., YVON J., BOUCHELAGHEM, A.,Colloid. Surface. A, 111, 1996, p.1674. VACCARI, A., Catal. Today, 41, 1998, p.535. SEFTEL, E.M., DVININOV, E., LUTIC, D., POPOVICI E., CIOCOIU, C.,J. Optoelectron. Adv. M., 7(6), 2005, p.28696. YANG, W., KIM, Y., LIU, P. K. T., SAHINI, M., TSOTSIS, T. T., Chem.Eng. Sci., 57, 2002, p.29457. FORANO, C., GRAUT, E., PREVOT, V., LEROUX, F., ALEKSEEVA, T.,BOUHENT, M., DERRICHE, Z., RAFQAH, S., SARAKHA, M., n: Abstractsof 43rd Annual Meeting of CMS 4eme Colloque du GFA, June 3-7, France,2006, p. 958. CURTIUS, H., KATTILPARAMPIL, Z., Clay Miner., 40, 4, 2005, p.4559. PALOMARES, A. E., PRATO, J. G., REY, F., CORMA, A., J. Catal., 221,p. 6210. DAS, D. P., DAS, J., PARIDA, K., J. Colloid Interf. Sci., 261, 2003,p.21311. GUPTA, V. K., Ind. Eng. Chem. Res., 37, 1998, p.19212. LAZARIDIS, N. K., Water Air Soil Poll., 146, 2003, p.12713. POPOVICI, E., SEFTEL, E.M., PODE, R., COCHECI, L., PODE, V., n:Abstracts of 43rd Annual Meeting of CMS 4eme Colloque du GFA, June3-7, France, 2006, p.21914. MANEA, F., BDULESCU, R., CPN, C., Rev. Chim.(Bucureti),55, nr.11, 2004, p.83915. MORSE, G.K., LESTER, J.N., Sci. Total Environ., 212, 1998, p.6916. DIMIRKOU, A., IOANNOU, A., DOULA, M., Advan. Coll. Interfac.,97, 2002, p.3717. HUNG, C.H., PAVLOSTATHIS, S.G., Wat. Res. 31, 1997, p.276118. MANEA, F., Rev. Chim.(Bucureti), 55, nr.4, 2004, p.21719. EATON, A. D., CLESCERI, L. S., RICE, E. W., GREENBERG, A. E.,(Eds.) Standard Methods for the Examination of Water and Wastewater,21st Edition, American Public Health Association, Washington, DC, 2005,p. 4 15120. ***, Die Untersuchung von Wasser, E. Merck, Darmstadt21. JAYCOCK, M. J., PARFITT, G.D., Chemistry of Interfaces, EllisHorwood Ltd., Onichester, 1981, p.95


Fig. 4. Curba cinetic corespunztoare adsorbiei anionuluitiocianat. Inserare: liniarizarea corespunztoare ec. (6)

0 100 200 300 400 500 6000

10

20

30

40

50

0 100 200 300 400 500-7

-6

-5

-4

-3

-2

-1

0

ln(1-

q t / q

e)

Timp [min]

q t [m

g/g]

Timp [min]

0 100 200 300 400 500 6000

5

10

15

20

25

30

35

0 100 200 300 400 500-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

ln(1-

q t / q

e)

Timp [min]

q t [m

g/g]

Timp [min]

Fig. 3. Curba cinetic corespunztoare adsorbiei anionului fosfat.Inserare: liniarizarea corespunztoare ec. (6)

Tabelul 2VALORI ALE CONSTANTELOR DE VITEZ

15


Combinaii complexe ale unor metale tranziionalecu noi tioureide N, N- disubstituite

RICA BOCENCU1*, VERONICA NACEA1, CARMEN LIMBAN1, ALEXANDRU MISSIR1, RADU SOCOTEANU21Universitatea de Medicin i Farmacie Carol Davila Bucureti, Facultatea de Farmacie, Str.Traian Vuia, Nr.6, 020956, Bucureti, Romnia2 Academia Romn, Institutul de Chimie Fizic I.G. Murgulescu, Splaiul Independenei, Nr. 202, 77208, Bucureti, Romnia

A series of metal complexes of Ni(II), Cu(II) and Cu(I) have been synthesized with newly prepared biologicallyactive ligands. The structure of the formed copper complexes with N,N-disubstituted phenyl thiourea ligandswas established via physicochemical studies including IR, UV-VIS, ESR spectral measurements.

Keywords: thiourea derivatives, copper complexes, nickel complexes

Combinaiile complexe ale ionilor metalici 3d cu liganzidin clasa tioureidelor N,N- disubstituite au fost multstudiate n ultimii ani, n special pentru activitatea lorbiologic. Astfel, o serie de combinaii complexe generatede ionii metalici Cu(II), Ni(II), Co(II) i tioliganzi suntcunoscute pentru activitatea lor antifungic. Ionii metaliciMn(II) i Cu(II) formeaz cu derivai de tip N-acil-N-alchiltiouree combinaii complexe cu activitate antitumoral [1-6].

Partea experimentalAu fost sintetizate nou combinaii complexe cu ionii

metalici Ni(II), Cu(I) i Cu(II) utiliznd liganzi din clasatioureidelor N,N- disubstituite, care prezint o formulstructural de tipul:

Sintezele combinaiilor complexe ale Cu(I)La o soluie fierbinte ce conine 2 mmoli ligand dizolvai

n 20mL alcool metilic se adaug o soluie de CuCl2 ( 1mmolCuCl2 ) n alcool metilic (15 mL).

Amestecul de reacie se nclzete sub agitare la 60C,timp de 30 min. Produsul final se filtreaz iar cristalele deculoare galben obinute, se spal cu alcool metilic, seusuc i se purific prin recristalizare din cloroform.

Utilizarea excesului de ligand este obligatorie pentru amenine starea de oxidare inferioar a cuprului, procesbazat pe caracterul reductor al liganzilor.

Sintezele combinaiilor complexe ale Cu(II)O soluie ce conine 2mmoli Cu(CH3COO)2 . H2O dizolvai

n ~ 25mL alcool metilic se adaug peste soluia ligandului(1mmol ligand n 20mL alcool metilic) i se agit latemperatura camerei. Soluia ce conine produsul final sefiltreaz i se obin precipitate de culoare verde-kaki, carese spal cu metanol i se usuc n etuv la 100C.

Pentru a preveni reducerea ionilor Cu (II) la Cu(I) selucreaz cu un exces de acetat de cupru ( raport molarmetal:ligand 2:1) i la temperatura camerei.

Compuii obinui sunt stabili n condiii atmosferice isunt solubili n cloroform i DMF.

Sintezele combinaiilor complexe ale Ni(II)O soluie ce conine 2mmoli Ni(CH3COO)2.4H2O dizolvai

n ~ 30 mL alcool etilic se adaug la o soluie etanolic deligand (4mmoli ligand dizolvai n 20 mL alcool etilic).Amestecul se nclzete la 600C sub agitare continu, timpde o or. pH-ul acestui amestec se aduce la valoarea ~6cu ajutorul unei soluii apoase de amoniac. Soluia secoloreaz n brun - rocat. Peste aceasta se adaugaproximativ 50 mL ap distilat iar produsul de culoarebej care se formeaz este filtrat, splat repetat cu alcooletilic i uscat.

Combinaiile complexe nou sintetizate au fost analizateprin analiz elemental, spectroscopie n IR, UV-VIS, RPE.

Determinri fiziceAnaliza elemental de C, H i N s-a realizat cu ajutorul

unui analizor automat tip Carlo Erba, model L-1108, iar ionulmetalic s-a dozat gravimetric i volumetric.

unde:R = 4-clorfenil, L1= N-(2-fenoximetil)-benzoil-N-(4- clorfenil)-tioureeR = 3-clorfenil, L2= N-(2-fenoximetil)-benzoil-N-(3- clorfenil)-tioureeR = 2-clorfenil, L3= N-(2-fenoximetil)-benzoil-N-(2- clorfenil)-tiouree

Sintezele liganzilor s-au realizat prin reacia dintreclorura acidului 2-fenoximetilbenzoic, tiocianatul deamoniu i amina corespunztoare, utiliznd ca mediu dereacie acetona anhidr. Purificarea liganzilor s-a realizatprin recristalizare din alcool izopropilic n prezenacrbunelui animal [7]. Liganzii sunt uor solubili ncloroform i aceton i solubili la cald n alcool etilic imetilic.

Tioureidele N,N-disubstituite utilizate ca liganzi auparticulariti structurale deosebite i capacitatecoordinativ mare, consecin a prezenei n structura lora atomilor donori O, S, N. Astfel, n funcie de natura ionuluimetalic i condiiile reaciei de complexare, acetia potgenera combinaii complexe cu geometrie tetraedric,octaedric sau plan-patrata [8-18].

* (+40) 3180743 / 232


Spectrele IR au fost nregistrate cu ajutorul unuispectrometru cu transformat Fourier, de tip Nicolet Impact400D FTIR. Substanele de lucru uscate timp de 24 h la150oC au fost prelucrate sub form de pastil n KBr depuritate spectroscopic, iar domeniul spectral studiat a fostcuprins n intervalul 4000-500cm-1.

Spectrele electronice ale combinaiilor complexe nousintetizate au fost nregistrate n soluie cloroformic cuajutorul unui spectrometru UV-Vizibil model SPECORDM400 Carl Zeiss Jena.

Spectrele RPE ale combinaiilor complexe nousintetizate au fost nregistrate n stare solid la temperaturacamerei, cu ajutorul unui spectrometru ART-6 model IFABucureti, care opereaz n band X (9.01GHz), echipatcu o unitate de modulaie a cmpului de 100KHz.Spectrometrul a fost cuplat cu un calculator. Pentruetalonarea cmpului magnetic s-au utilizat Mn(II) n MgO.

Rezultate i discuiiRezultatele obinute prin analiza elemental a

combinaiilor complexe nou sintetizate sunt redate ntabelul 1.

Tabelul 2ATRIBUIRILE VIBRAIILOR CARACTERISTICE DIN SPECTRELE IR ALE TIOUREIDELOR N,N-DISUBSTITUITE

Tabelul 1REZULTATELE ANALIZEI ELEMENTALE PENTRU COMBINAIILE OMPLEXE ALE Cu(I), Cu(II) I Ni(II),

CU NOI TIOUREIDE N,N- DISUBSTITUITE

Analiza comparativ a spectrelor IR ale combinaiilorcomplexe nou-sintetizate cu cele ale liganzilorcorespunztori (sub forma atribuirilor n tabelele 2 i 3) apermis stabilirea atomilor implicaci n coordinare.

n spectrele IR ale liganzilor n regiunea spectral 3020 -3280 cm-1 apar dou benzi de absorbie de intensitatemedie care pot fi atribuite frecvenelor de vibraie NH.

Benzile de absorbie atribuite frecvenei de vibraie agruprii carbonilice C=O, sunt situate n jurul valorii de 1670cm-1.

Regiunea spectral 1475- 1522 cm-1 este caracterizatde prezena a dou benzi de absorbie intense care pot fiatribuite frecvenei vibraiei de ntindere asNCN. Benzile deabsorbie de intensitate medie poziionate n spectru IR lavalori ~1310 - 1450 cm-1 pot fi atribuite unei contribuii mixtea frecvenelor de vibraie C-N + C-S.

Comportarea spectral IR a combinaiilor complexeformate de ionii monovaleni ai cuprului cu liganzii de tiptioureide N,N-disubstituite indic o coordinare mono-dentat a ligandului la ionul metalic, prin intermediulatomului de sulf tiocarbonilic. Acest lucru este confirmat

17


de prezena n spectrele IR ale combinaiilor complexe aleCu(I) a celor dou benzi de absorbie atribuite frecvenelorde vibraie NH precum i a benzii de absorbie atribuitgruprii carbonilice, C=O.

Analiza spectral IR a combinaiilor complexe ale Cu(II)i Ni(II) pune n eviden dispariia celor dou benzicorespunztoare frecvenelor de vibraie NH din regiuneaspectral 3020-3280 cm-1, fapt care sugereaz deprotonarea

Tabelul 3ATRIBUIRILE VIBRAIILOR CARACTERISTICE

DIN SPECTRELE IR ALE COMBINAIILORCOMPLEXE ALE Cu(I), Cu(II) I Ni(II)

Tabelul 4ATRIBUIREA TRANZIIILOR N

SPECTRELE ELECTRONICE ALETIOUREIDELOR N,N-DISUBSTITUITE

I COMBINAIILOR COMPLEXE CU IONIICu(I), Cu(II), Ni(II)

ligandului n timpul coordinrii ionilor divaleni ai cuprului,respectiv ai nichelului.

Deplasarea benzii de absorbie atribuit frecvenei devibraie C=O cu aproximativ 60 cm

-1 i diminuareaintensitii acesteia confirm implicarea gruprii carboniln coordinarea ionului Cu(II), respectiv Ni(II).

Modificri spectrale apar i n domeniul 1475-1522 cm-1,unde se constat prezena unei singure benzi de intensitate

18


Tabelul 5PARAMETRII MAGNETICI OBINUI DIN SPECTRELE RPE PENTRU COMPLECII Cu(II)

foarte mare i care este uor deplasat ctre numere deund mai mici.

Deplasri ctre numere de und mai mari comparativcu spectrul liganzilor nregistreaz i banda atribuitfrecvenei CN ceea ce sugereaz o cretere a caracteruluide legtur parial dubl.

Banda de absorbie specific frecvenei de vibraie CSse deplaseaz cu ~10-15cm-1 ctre numere de und maimici n spectrul IR al combinaiilor complexe fa de poziiaacestora din spectrele IR ale liganzilor.

Acest fapt este pus pe seama coordinarii liganzilor iprin intermediul atomilor de sulf tiocarbonilici.

Interpretarea spectrelor IR n cazul combinaiilorcomplexe cu ionii Ni(II) i Cu(II) demonstreaz ocomportare de ligand bidentat, prin atomii de sulftiocarbonilic i oxigen carbonilic, pentru derivaiidisubstituii de tiouree.

Rezultatele obinute prin analiza spectrelor electroniceale liganzilor i combinaiilor complexe ale acestora cu ioniimetalici Cu(I), Cu(II), Ni(II) sunt redate n tabelul 4.

Analiza spectral UV a liganzilor pune n evidenexistena a dou tipuri de tranziii electronice intraligand,tranziii de tip *(~250nm) i n - *(270-290nm).

n spectrele electronice ale complecilor Cu(I) seregsesc, la lungimi de und mai mari, doar cele doubenzi prezente i n spectrele liganzilor liberi. Acest lucruconfirm obinerea combinaiilor complexe care coninioni de cupru monovalent, deoarece pentru cationii cuconfiguraie d10 teoria cmpului cristalin nu prevede tranziiielectronice n domeniul vizibil.

Spectrele electronice ale combinaiilor complexe aleCu(II) conin patru benzi de absorbie cu maximepoziionate n regiunea spectral 250-640nm. Primele doubenzi de absorbie pot fi atribuite tranziiilor intraligand:* (250-260nm)i n - *(280-300nm) n timp ceurmtoarele dou sunt benzi caracteristice tranziiilor cutransfer de sarcin (~420nm) respectiv tranziiilor d-d ntr-o geometrie plan ptrat (~630nm).

Analiza spectrelor electronice ale combinaiilorcomplexe formate de ionii Ni(II) cu tioureidele N,N-disubstituite indic pentru acestea o geometrie plan -ptrat.

Analiza prin RPE a complecilor Cu(II) a permisconfirmarea ipotezei cu privire la structura geometric detip plan-ptrat a complecilor Cu(II).

Valorile parametrilor magnetici obinui din spectreleRPE ale combinaiilor complexe ale ionilor Cu(II) cu liganzide tip tioureide N,N-disubstituite, spectre nregistrate pepulbere monocristalin la temperatura camerei, suntprezentate n tabelul 5.

Factorul de scindare giso are valori cuprinse ntre 2,083-2,087 iar constantele de cuplaj hiperfine izotrope (Aiso) auvalori cuprinse n intervalul 69-78G i sunt tipicecombinaiilor complexe ale Cu(II) cu simetrie plan-ptrat(D4h) [19,20].

ConcluziiSinteza i studiul celor nou combinaii complexe ale

Ni(II), Cu(I) i Cu(II) cu liganzi din clasa tioureidelor N,N-disubstituite evideniaz unele aspecte privind capacitateacoordinativ a acestui tip de liganzi i geometriile posibilde adoptat de ctre acetia n raport cu ionii metalicicoordinai.

Prin corelarea datelor obinute din spectrele UV-VIS iRPE se poate atribui o geometrie de tip plan-ptratcomplecilor Cu(II) i Ni(II). n cazul cationilor Cu(I) liganziicoordineaz prin atomul de sulf tiocarbonilic compor-tndu-se ca liganzi monodentai, n timp ce datelespectrale IR confirm comportarea de liganzi bidentai fade cationii Cu(II), Ni(II).

Bibliografie1. BLANZ E., FRENCH F., Cancer Res., 28, 1965, p. 24192. FRENCH F., BLANZ E., AMARAL D.J., FRENCH D., J. Med.Chem., 13,1970, p. 11173. MOHAPATRA B.B., GURU S., MOHAPATRA B.K., J. Inorg. Nucl. Chem.,39, 1977, p. 22914. ANTHOLINE W., TAKETA F., J. Inorg. Biochem., 16, 1982, p. 1455. SHEN X., SHAN J., SUN H., KANG B., J. Chinese. Chem. Soc., 46,1999, p. 1796. HERNANDEZ W., SPODINE E., MUNOZ J. C., BAYER L., FERREIRA J.,Bioinorg. Chem. Appl., 1, 2003, p. 2717. LIMBAN C., MISSIR AL., CHIRI I., Farmacia, 48, nr.6, 2000, p.738. NACEA V., MISSIR AL., BADEA R., Farmacia, 1-4, 1992, p.839. NEGOIU D., CRCU V., ROSU T., BDICU N., Rev. Chim.(Bucureti),50, nr. 2, 1999, p. 8810. NACEA V., BOCENCU R., MISSIR AL., LIMBAN C., BRBUCEANU., Rev. Chim.(Bucureti), 56, nr.1, 2005, p.6811. BOCENCU R., MISSIR AL., NACEA V., SOCEA L.,Rev.Chim.(Bucureti), 56, nr. 5, 2005, p.46912. MOHAMADOU. A., DECHAMPS-OLIVER I, BARBIER JP., Polyhedron,13, 1994, p.136313. MOHAMADOU. A., DECHAMPS-OLIVER I, BARBIER JP., Polyhedron,13, 1994, p.327714.GUILION E., MOHAMADOU. A, DECHAMPS-OLIVER I,BARBIER JP,Polyhedron, 15,1996, p.94715. XU SHEN, X. SHI, B. KANG, Polyhedron, 18, 1996, p.3316. SHOUKRY M, MAHGOUB A, ELNADI F. J. Inorg. Nucl. Chem., 42,1980, p.117117. JONES M.M., J.Coord.Chem., 23, 1991, p.18718. NARAD S., MISHRA N.N., PANDEY P., KUMAR A., PITRE K.S., Anal.Lett., 28, 1995, p.200519. GUILLON E., DECHAMPS-OLIVIER I., MOHAMADOU. A., BARBIERJP, Inorg. Chim. Acta, 268, 1998, p.1320. RICHTER R., BEYER L., KAISER J., Z.anorg. allg. Chem., 461, 1980,p.67


19


Effect of Ultrasounds Irradiation on the Electrolytic Growth of Nanocrystalline Ni Films

NICOLAE SULIANU1*, CRISTIAN PRGHIE2, ION SANDU31 Al.I.Cuza University of Iasi, Faculty of Physics, Department of Solid State Physics and Theoretical Physics, 11 Carol I Blvd.,700506, Iasi, Romania2 Stefan Cel Mare University of Suceava, Faculty of Mechanical Engineering,, Str. Universiti, Nr. 13, 720225 Suceava, Romania3 Al.I.Cuza University of Iasi, Department of Cultural Heritage, 9 Closca Str., 700066 Iasi, Romania

The present study reports the effects of ultrasounds irradiation on both charge transfer processes andinterfacial structures in acid nickel sulfate electrolytes by various electrochemical methods. Moreover, thesurface structure of electrolysis product-Ni film was evidenced by AFM. In order to determine optimumelectrolysis parameters, we investigated the current-potential curves (voltammograms) at copper electrodeand Ni ion collision speed with Cu substrate for different powers of ultrasonication processes. The bathefficiency has been also studied as a function of the time and the current density applied. The ion collisionspeed, bath efficiency, the hardness, the brightness and the adherence of the electrodeposits increase withthe ultrasonic agitation, in comparison with the same film produced from still or magnetic stirred baths.Surface analyses of Ni films are performed using atomic force microscopy (AFM). Both surface roughnessand grain size are the important factors in all areas of nanotribology and in evaluating the quality of ananostructured surface operation. The results show that there exists optimum ultrasound sonication intensitywhere the mechanical properties of the Ni films are mostly enhanced. Moreover, results indicate that thegrain size of nanocrystalline Ni film change with different sonicating intensity.

Keywords: sonoelectrochemistry, electrodeposition, nanocrystalline film, atomic force microscopy

It has been showed that making less in size of materialsto nanoscale brings out peculiar properties which have notbeen observed in the bulk materials [1]. The quantum sizeeffects of nanomaterials may induce unique electronic,optical and magnetic properties compared with those intraditional bulk materials. Their nanometer-scaledimensions may allow new structures that could serve aspotential building blocks new devices. The quantum sizeeffects of nanomaterials may induce unique electronic,optical and magnetic properties compared with those intraditional bulk materials. Their nanometer-scaledimensions may allow new structures that could serve aspotential building blocks new devices. In the last decade,many methods have been explored to produce variousnanomaterials, such as gasliquid precipitation, molecularbeam epitaxy (MBE), metalorganic chemical vapordeposition (MOCVD), organometallic vapor phase epitaxy(MVPE), electrochemical methods, solvothermal methods,ac-radiation synthesis, microwave assisted preparation andsonochemical synthesis et al [2, 3]. Among these methods,sonochemical synthesis has been paid more extensiveattention due to its special potential applications. Currently,the sonochemical process has been proved to be a usefultechnique for generating novel materials with unusualproperties, since it results in particles of a much smallersize and high surface area than those produced by othermethods. The chemical effects of ultrasound, which arisefrom acoustic cavitation, formation growth and implosivecollapse of a bubble in a liquid, will produce unusualchemical and physical environments [4, 5].

Previous works [612] have shown that ultrasonicirradiation yield interesting effects (e.g. good yields, shortreaction times and mild reaction conditions) and that theplating rates and deposit properties can be improved


considerably, especially if ultrasonic irradiation takes placeduring both activation and plating steps [13]. Moreover,there is an upsurge of interests in the use of sonoelectro-chemistry in other subject areas such as the production ofactive metal particles, electrosynthesis, corrosion andelectrochemical dissolution, the deposition of polymerfilms [14-18]. In sonoelectrochemistry, the effects ofultrasonic irradiation on mass transport processes inreversible electrochemical systems have been widelyreported [1, 2]. However, it was evidenced that theimposition of an ultrasound accelerated charge transferprocesses in electroplating systems of nickel [3] and copper[4], the mechanism of contributions of ultrasound to chargetransfer processes has not been elucidated in detail.

Here, the application of ultrasound in electrodepositionprocess of metallic (Ni) coating (thin films) is discussed. Acritical review concerning to cathode process underultrasound irradiation, e.g. the voltage-current charac-teristic of the electrolyze cell irradiated at various ultrasonicintensities and the estimation of average collision velocityof Ni ions on the cathode, is discussed. Moreover, thesurface structure of deposits obtained from silent and,respectively, under ultrasounds electrolyte irradiation isalso given. Finally, criteria for electrodeposition of thin filmsunder ultrasounds irradiation are discussed.

Experiment descriptionExperimental apparatus Figure 1 shows a schematic representation of theelectrodeposition cell used in our experiments. Halfwaybetween two Ni anodes fixed to the lateral walls of theparallelepipedic electrolyze cell, a mobile cathode issuspended by a torsion metal thread, rigidly fixed by twoconsoles.


The mobile cathode was made of thin copper sheethaving the shape shown in figure 1. Lateral blades aresquare (l = 3 x 10-3 m) and are separated by a copper strapof 2 mm width; the distance between the centres of thelateral blades is L = 5 x 10-2 m. One of the lateral blades aswell as the linking strap was covered with varnish to avoidelectrodeposition (the hachured surface in fig. 1). A mirrorO is attached to the torsion thread whose torsion constantis c = 7.2 x 10-6 Nm/rad. Using a light beam and a ruler Rwe can determine the rotation angle = d/D (D = 2m).

Ultrasound generationAll experiments were performed with a high frequency

generator of 2 MHz from electronic service, at variousultrasonic intensities: 1, 2, 4, 6, 8 and 10 kW/m2, in aelectrolyze cell filled with 400 mL liquid electrolyte.Ultrasonication is produced perpendicular to the electrolytesurface that is perpendicular to the ionic current andparallel to the surface of mobile cathode hung up vertically.In order to determine precisely both ultrasound parametersin bath and agitation-induced effects, the characterizationof exposure conditions was needed. The transduceremission surface was 3.2 cm2 and the ultrasonication timeof 30 s. Acoustic power transmitted to the liquid electrolytewas determined by calorimetry [21]. Mass transfermeasurements were characterized by electro-diffusionmethod [2224].

Electrodeposition processAs supports of Ni deposits (thin films) copper conductive

substrates of 50 x 5 x 3 mm were used previouslyelectrodeposited on a sensitized and activated poly-carbonate plates. Table 1 summarizes the condition for Nifilm electrodeposition.

Before Ni electrodeposition, the copper substrate waschemically cleaned with natrium hydroxide aqueoussolution for 5 min. It was used an aqueous electrolyte basedon nickel sulphate. For solution pH =1.8 and bathtemperature 300 K, the current density was adjusted duringdeposition to 12 mA/cm2.

Results and discussionThe use of ultrasounds during the electroplating causes

the formation of cavitation bubbles, which collapse on thesolid surface and promote the agitation of the solution.These microjects directed towards the surface enhancethe momentum, heat and mass transfer into the electrolyticbath [2, 3]. So, the diffusion layer near the cathode isdecreased [4] and the electrode surface is activated,advancing conditions to obtain good electrodeposits.

The current-voltage characteristic of electrolytic cell A typical voltametric curve exhibits a sigmoidal current

response yielding a signal plateau at mass transport limitedpotential. Only the steady state value is considered. Figure2 shows the current-voltage characteristic of the electrolyticcell. This characteristic has a linear variation between 2Vand 4V applied voltage.

Fig. 1. Schematic representation of the electrodeposition cell

Table 1CHEMICAL COMPOSITION AND OPERATING CONDITIONS OF THE

PLATING BATH

Fig.2. The current-voltage characteristic of the Ni electrodeposition cell

By applying a continuous voltage U on electrolytic cellelectrodes, an electric field occurs between the anode andcathode. In the presence of this field, in the electrolyteoccurs a continuous electric current with two componentsfaradic electric current and non-faradic electric current.As a result of the faradic current positive ions cross theboundary of potential and, in the end, fall on the cathodewith a certain average velocity lv . Because after the ionneutralization their adsorption at the surface cathode takesplace, we can consider that the ions plastically collidethe cathode. Due to the irreversible processes that takeplace in electrolytic cell, the electric current I changesfunction on tension voltage U. The silent system (fig. 2,curve-0 kW/m2) shows a flat plateau, the limiting current,while in the case of ultrasonication, the shape is acharacteristic smooth increase for all ultrasoundsintensities as shown in figure 2 (curves: 4, 6, 10 kW/m2).As a consequence, the surface efficiency of an electrodeincreases when is exposed to the ultrasonication and thismay be useful in the design and assembly of practicalsensor systems [25]. The current-voltage characteristic isspecific for each electrolytic cell.

The collision velocity between the Ni ions and the cathodein silent electrolyte

For the begining, we attempt to calculate the expressionfor average velocity of collision of the Ni2+ ions with the Cucathode [7, 8]. At the same time, we will emphasize theway in which the mentioned proportion changes when theelectrolyte is under the effect of ultrasounds.

Considering that between 2V and 4V the number of ionswhich change collision speed with one unit is proportional

21


to the voltage applied to the clamps of the electrolytic cell,that is:

aUdvdN

l

=. (1)

The first member can also be written as:

ll dv

dUbdvdU

dUdN

=. (2)

Here a and b are proportionally constants. From relations(1) and (2) results:

UAdvdU

l

= , (3)

where A = a/b, respectively

ldvAUdU

= . (4)

By integration we get:

CvAU l +=ln . (5)

We consider C=lnU0=0, (U0=1 V) and, finally, results:

UAl

vl ln= . (6)

Because 1A has the physical dimension of velocity, we

consider that the proportion is the same as one tenth ofthe average velocity of the molecules according toMaxwells distribution, that is:

. /1 RT0 16 33m sA M= = (7)

with R=8310 J/kg K; M=59.7 kg/kmol; T=300K.From (6) and (7) results the theoretical expression of

the average velocity of collision between Ni ions andcathode (substrate), vt:

Uvt ln33 = (m/s). (8)

Due to the collision between Ni ions and substrate (fig.1), the system rotates with an angle . At the equilibriumwe can write:

FL dc

2 D=

(9)

=

=

=

=

N

i

li t

vm

t

vm

t

vmF

1 . (10)

Here, m is the deposited mass, f i iv v v v = = that isapproximately the same as the average velocity of theincidental ions v and Dt is time after that the Ni ion velocitybecomes zero.

According to Faradays law:

'

1m ki t

2= . (11)

Considering t t, we obtain the following expressionfor the experimental value of the average velocity ofcollision between Ni ions and the cathode:

.

2cd d mv 0 48

kild i s

= =

(12)

Figure 3 shows the tension voltage dependence ofcurrent density and Ni ion collision velocity for a silentelectrolysis bath.

The collision velocity of the ions against the cathode andcurrent intensity in the silent bath continuously increaseswith the increase of the voltage. A good correlation wasfound between experimental values (fig. 3) and thosecalculated (12).

In the case of the electrolyte ultrasonication, at the placeof the mobile cathode with the frequency of f = 2 MHz anddifferent intensities I, it was found an increase of theaverage collision velocity with the increase of the intensityof ultrasounds.

Figure 4 shows the experimental ultrasound intensitydependence of current density and Ni ion collision velocityfor an ultrasonicated bath. The collision velocity reaches aplateau value at high ultrasound intensities, while thecurrent intensity continuously increases in anultrasonicated bath. This means that at higher ultrasoni-cation intensity, higher than 5-6 x 103 kW/m2, the effects ofultrasounds irradion on the electrode process keep thesame.

Fig. 3. Current density and ion collision velocity as a function oftension voltage in silent electrolysis bath

Fig. 4. Current density and Ni ion collision velocity as function ofultrasound intensity at 2 V tension voltage between electrodes

Through empirical trials we established a relation forthe calculation of the average collision velocity accordingto the intensity I of the ultrasounds:

22.8 0.1tv I= + (13)

Therefore, normal collision velocity changes functionof ultrasounds intensity as I1/2. A good correlation betweenexperimental and theoretical values is observed.

The changes in average collision speed under the effectof ultrasounds are mainly due to the changes in variouscharacteristic values of the electrolytic process under action

22


of ultrasounds such as: electrolyte conductibility,dehydration degree, electric permitivity. The imposition ofultrasound gave rise to decreasing cathodic overpotential,increasing exchange current density and accelerated thecharge transfer process at the metalelectrolyte interfacein the electrodeposition, and these effects depended uponthe ultrasonic frequency. The values of exchange currentdensity were dependent upon the measured electrodepotentials.

The surface microstructure of Ni filmsFigure 5 shows AFM images for some selected Ni films.

The grain average size varies as function of ultrasoundpower, for 2 Mhz frequency, and their distribution all alongthe sample is altered (fig. 5). For a 2 kW/m2 intensity, asmooth film surface with fine grain structure (nanograins)is evidenced (fig. 5, Picture b). An analogous surfacestructure was evidenced in a previous work [3] where suchfine grained surface structure was observed on Nielectrodeposited in presence of organic inhibitor, such isthiourea [27]. AFM pictures of ultrasonicated films (fig. 5,Picture b-d) illustrate this, showing grain arrangements inthe mat areas as though the deposit were made withoutultrasound irradiation (fig. 5, Picture a), with small, roundedand unorganised grains. In the bright areas, grains areorganised in perpendicular lines to wave propagationdirection. Because grain size depends on ultrasonic power,this leads us to consider that mat areas correspond topressure nodes. We can see that in bright area whichcorresponds to wave propagation direction, nanograinshave pyramidal forms and do not exhibit a privilegedorientation, with low ultrasound influences. Finally,ultrasonic irradiation does not modify deposit thicknessfor low and high ultrasonic power (2 or 10 kW/m2), but itseems that there is a little thickness diminution forintermediary ultrasonic power (fig. 5, Picture c: 6 kW/m2).

AFM is the perfect tool for quantitatively detecting andmaking visible roughness and textures in the nano range.Controlling roughness and texture down to only a fewnanometers is very important in various areas of researchand industr y. Certain optical and/or mechanicalcharacteristics of materials, e.g. friction characteristics,depend on the nano roughness. The AFM images can becut and various parameters, such as the mean roughnessdepth Rzm, the arithmetic average roughness depth Rza,the root mean square roughness Rqm or the arithmeticaverage roughness Rqa, can be quantitatively detected andvisualized along theses cuts. The measured and calculatedvalues of roughness for Ni film irradiatiated at differentultrasound powers are summarized in table 2.

Fig. 5. Surface AFM images of nanocrystalline Ni films as function ofultrasound power realized under ultrasonic irradiation at 2 MHz.

Picture (a): silent conditions. Picture (b): ultrasonic irradiation at 2kW/m2. Picture (c): at 6 kW/m2. Picture (d): at 10 kW/m2

Table 2ROUGHNESS OF ULTRASOUND IRRADIATED NI FILMS FOR

DIFFERENT ULTRASOUND POWERS

The properties of ultrasound irradiated Ni films areimproved using low ultrasonic power, short irradiationtimes and high frequencies. It is known that normal graingrowth requires a certain optimum current density [26].Finally, under ultrasound waves, the film is compact andthe effect of the typical mechanical action imposed bybubbles cavitation can be seen on the surface ofelectrodeposited metal [7]. This structure confirms theeffect of ultrasonics in the production of harder deposits.

ConclusionsThe speed at which the ions collide the cathode during

the deposition processes has a significant importanceconcerning the structure of the thin films. The fact that ionspeed is different when the electrolyte is under the actionof the ultrasounds leads to changes in their properties. In

23


the future, the changes in the structure of the thinelectrodeposited films, as well as the changes of thecoercive field and of the saturation magnetization of thefilm must be analyzed at the same time with the changesof the velocity at which the ions collide the cathode.

It may be pointed out that the experimental results haveshown that the physico-mechanical properties ofelectrodeposited nickel undergo substantial changes whenthe process is accompanied by high current densities.

Ultrasounds action on nickel electrodeposits reducessubstantially the polarization phenomena, enhances theefficiency of the plating rate and changes thephysicochemical properties of the electrolytic nickel.

Under the influence of ultrasound it is possible toproduce hard, compact and adherent electrodeposits evenusing high current densities in the electroplating process.

References1. MASON, T.J., LUCHE, J.-L., R.V. ELDICK, R.V., HUBBARD, C.D. (Eds.),Chemistry under Extreme or Non-Classical Conditions, Wiley, NewYork, 1997, p. 3172. KELSALL, R., HAMLEY, I.W., GEOGHEGAN, M. (Eds.), NanoscaleScience and Technology, Wiley, New York, 20053. SULIANU, N., SANDU, I., SANDU, I-G., Rev Chim (Bucureti) 54,2003, p. 6704. SUSLICK, K.S., DOKTYCZ, S.J., Advances in Sonochemistry, 1, Mason,T.J. (Ed.), Elsevier-JAI Press, 19905. WALKER, R., Advances in Sonochemistry, 3, Mason, T.J. (Ed.),Elsevier-JAI Press, 1993.6. SUSLICK, K.S., Ultrasound, its Chemical, Physical and BiologicalEffect, VCH, Weinheim, Germany, 19887. ZHAO, Y., BAO, C., FENG, R., CHEN, Z., Ultrasonics Sonochemistry 2,1995, p. 998. TOUYERAS, F., HIHN, J.Y., DOCHE, M.L., ROISARD, X., UltrasonicsSonochemistry 8, 2001, p. 285

9. COHEN, R.L., WEST, K.W., Technologies Internationales 80, 2002,p. 2610. BONRATH, W., Ultrasonics Sonochemistry 10, 2003, p. 5511. SCHEFFEL, M., PH.D. Thesis, Iai, 197912. MASON, T.J., LORIMER, J.P., Applied Sonochemistry, Wiley-VCHVerlag GmbH & Co. KGaA, 2003.13. TOUYERAS, F., HIHN, J.Y., DELALANDE, S., VIENNET, R., DOCHE,M.L., Ultrasonics Sonochemistry 10, 2003, p. 36314. LIGIER, V., HIHN, J.-Y., WRY, M., TACHEZ, M., J. Appl. Electrochem.31, 2001, p. 21315. DOCHE, M.L., HIHN, J.-Y., TOUYERAS, F., LORIMER, J.P., MASON,T.J., PLATTES, M., Ultrasonics Sonochemistry 8, 2001, p. 291.16. MIZUKOSHI, Y., SEINO, S., OKITSU, K., KINOSHITA, T., OTOME, Y.,NAKAGAWA, T., YAMAMOTO, T.A., Ultrasonics Sonochemistry 12, 2005,p. 19117. ZHANG, X., ZHAO, H., TAO, X., ZHAO, Y., ZHANG, Z., Materials Letters59, 2005, p. 174518. SULIANU, N., SANDU, I., Rev. Chim. (Bucureti), 54, 2003, p. 56119. KOBAYASHI, K., CHIBA, A., MINAMI, N., Ultrasonics 38, 2000, p. 67620. KOBAYASHI, K., CHIBA, A., TSUZUKI, K., MINAMI, N., Proceedingsof the 17th International Congress on Acoustics, Rome, Italy, 2-7,September 2001, p. 39321. MASON, T.J., LORIMER, J.P., D.M. BATES, D.M., Ultrasonics 30, 1992,p. 4022. F. TRABELSI, F., LYAZIDI, H.A., BERLAN, J., FABRE, P.L., DELMAS,H., WILHELM, A.M., Ultrasonics Sonochemistry 3, 1996, p. 12523. COOPER, E.L., COURY, L.A., J. Electrochem. Soc. 145, 1998, p. 199424. DOCHE, M.L., HIHN, J.Y., LORIMER, J.P., MASON, T.J., PLATTES, M.,Ultrasonics Sonochemisty 8, 2001, p. 29125. PHULL, S.J., WALTON, D.J., Advances in Sonochemistry, 4, Mason,T.J. (Ed.), Elsevier-JAI Press, 199626. BERGENSTOF NIELESEN, C., A . HORSEWELL, A., M.J.L.OSTERGARD, M.J.L., J. Appl. Electrochem. 27, 1997, p. 83927. SULITANU, N., BRINZA, F., Mater. Sci. Eng. B106, 2004, p. 155

Manuscript received: 5.11. 2006

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Bis(3-Halogeno ,5-diMethyl Salycilaldehyde)EthylenediamineCopper (II) Complexes

Synthesis and Characterization

AUREL PUI1*, MIHAELA-AURELIA VIZITIU21Al. I. Cuza University, Iasi, Faculty of Chemistry, 11 Carol I Blvd., 700506, Romania2 Gh. Asachi University, Faculty of Industryal Chemistry, 67 Dimitri Mangeron, 700050, Iasi, Romania

A series of di-halogeno tetra-Methyl Salen, Schiff base derivatives, and their copper (II) complexes weresynthesized and characterized. Their spectral properties and electrochemical behavior were investigated.The copper (II) complexes show a square-planar geometry with cis-N2O2 chromophores. The position of d-d band is influenced by the attractive capacity of electron presented by the substituent, X. Halogens andmethyl groups grafted on the ligand influence the electrochemical behavior of the complexes.

Keywords: halogeno-Schiff bases; copper (II) complexes; properties

Transition metal complexes containing quadridentateSchiff base ligands have been the subject of several studies[1-3]. Chelates of salen [H2Salen = bis(salicylaldehyde)ethylenediamine] containing cobalt (II) are known for theirdioxygen uptake compatibility, while those of chromium,manganese, copper, iron and nickel act as catalyst foroxidation reactions [4,5].

Copper has been known as an essential bioelement butits biological roles have been recognized only in the lastdecades. It plays a significant role in interaction betweenmodel complexes and protein biochemistry [6].

The present work reports synthesis, and characterizationof some copper (II) coordination compounds of di-halogeno tetra-Methyl Salen, Schiff base derivatives. Thecoordination of copper with Schiff bases has beeninvestigated and a considerable number of obtainedcomplexes have been characterized by the usualspectroscopic methods (UV-VIS, FT IR). Theelectrochemical properties of the complexes were studiedby cyclic voltammetry. It was seen that the aliphaticsubstituents on the azomethinic groups and the halogensgrafted on the ligand molecules modified the redox andcatalytic properties of the complexes.

Experimental PartSolvents and commercial starting materials of analytical

grade were used without further purification. Elementalanalysis (C, H, N) was performed by the Service deMicroanalyses de Gif-sur-Yvette, France. 1H-NMR spectrafor ligands were recorded on a Brucker AM 250 or AC 250spectrometers operating at 250 MHz. All spectra wereobtained in CDCl3 and chemical shifts calculated in ppmwith respect to TMS (d = 0) or solvent residual peak ( =7.26 for proton). UV-VIS spectra were taken on DES device,operating with the SAFAS program. The FT IR spectra wereobtained on a Bruker IFS 66 apparatus in KBr pellets.

Cyclic voltammetry experiments were performed on anAutlab apparatus. The recordings were made in a 2mMsolution in DMF under argon atmosphere, using lithiumperchlorate as electrolyte support. The following materialhas been used for analysis: as working electrode, a vitreouscarbon electrode (A = 4.0 mm2); as reference, electrode asaturated calomel electrode (SCE) and as auxiliaryelectrode, a platinum wire.

* e-mail: [email protected]

Preparation of the ligandsThe 2-hydroxy 3-chloro 5-methyl acetophenone has

been obtained by Friedel-Crafts substitution of thecorresponding dichlorophenols, with acetylchloride [ 7].The 2-hydroxy 3-bromo 5-methyl acetophenone wasobtained by brominating of 2-hydroxy 5-methyl aceto-phenone with pyridiniumbromochromate (PBC) [8]. The2-hydroxy 3-iodine 5-methyl acetophenone was obtainedby iodination of 2-hydroxy 5-methyl aceto-phenone withI2 in presence of HgO [9].

The ligands were obtained by condensation of 2-hydroxy3-halogeno 5-methyl acetophenone with ethylene-diaminein 2/1 molar ratio, in EtOH solution at 45C. The copper (II)complexes were synthesized by general methods, byreaction between ligand, dissolved in EtOH at 40C, andCu(OAc)6H2O solved in H2O, under vigorous stirring [3,5].A precipitate was deposited immediately. The mixture isfurther stirred at 40C for one hour. After cooling until roomtemperature, the solid is filtered and washed successivelywith water, ethanol-water mixture and absolute ethanol.After drying in vacuo, the copper complex is isolated andanalyzed (yield 60%). Anal. Calc. for C20H22N2O2Cu: C,62.24; H, 5.79; N, 7.26. Found: C, 62.05; H, 5.86; N, 7.19. Anal.Calc. for C20H20N2O2Cl2Cu: C, 58.81; H, 4.43; N, 6.16. Found:C, 58.67; H, 4.58; N, 6.19. Anal. Calc. for C20H20N2O2Br2Cu:C, 44.18; H, 3.71; N, 5.15. Found: C, 43.98; H, 3.82; N, 5.09.Anal. Calc. for C20H20N2O2I2Cu: C, 37.67; H, 3.16; N, 4.39.Found: C, 37.63; H, 3.25; N, 4.32.

Results and DiscussionThe ligands (H2L) have been prepared as reported in

literature, by condensation of the corresponding 2-OH, 3-X, 5-Me, acetophenone derivatives with ethylene-diamine,in 2/1 molar ratio. Then, the obtained Schiff bases (ligands)react with copper (II) ions, in 1/1 molar ratio (scheme 1).

All ligands were characterized by elemental analysis,FT IR, UV-VIS and 1H-NMR techniques. These analysesconfirm the structure of the ligand presented in scheme 1.The complexes were characterized by elemental analyses,UV-VIS and FT IR. The elemental analyses indicate theformation of the complexes in a 1:1 molar ratio (CuL).

The electronic spectra are measured at roomtemperature in DMF due to the low solubility of thecomplexes in other organic solvents. The complexes

25


spectra present modifications in the position and intensityof the bands characteristic to free ligands, as well as theapparition of new absorptions bands (table 1).

The copper complexes show a broad d-d transition bandat 556-600 nm. This d-d transition is in the region of thatobserved for structurally well-characterized complexes ofcopper (II) Schiff bases with square-planar geometry withC2v symmetry [11, 12]. The bands in the spectral range 266-404 nm are assigned as -* or n-* transitions from ligandmolecules and have become blue shifted uponcomplexation. Although the electronic spectra of thecomplexes are similar, the d-d band position is shifted tothe highest energy side with the diminution of electronattractive capacity of the substituent (X) in order Cl < Br


Table 3 ELECTROCHEMICAL DATA FOR COMPLEXES #

reversible peaks. The free ligands do not show oxidationor reduction peaks in the investigated range. Theelectrochemical data, the peak values Epa, Epc, thedifference from values Epa, Epc and E potentials for thecopper complexes are presented in table 3.

Examining the data presented in table 3 we can observethat the complexes present an irreversible behavior,according with other copper (II) complexes [16]. Thisbehavior can be explained by the electrical influencedetermined by halogens and methyl groups in thecomplexes [17].

ConclusionsGrafting of various substituents on the aromatic ring and

in the azomethinic group of Salen type ligands, lead to theobtaining of some new ligands. In reaction with Cu(II) ions,they form coordinative compounds with square planargeometry. Their properties are influenced by methyl groupsand halogen grafted on the molecule of ligand. Suchcompounds are of interest in oxygen reversible fixation andcatalytic activity.

References1. DHAR, S., NETHAJI,M., CHAKRAVARTY, A.R., Inorg. Chim. Acta, 358,2005, p. 24372.VIGATO, P. A., TAMBURINII, S., Coord. Chem. Rev., 248, 2004, p17173.NATHAN, L. C., KOEHNE, J. E., GILMORE, J. M., HANNIBAL, K. A.,DEWHIRST, W. E., MAI, T. D., Polyhedron, 22, 2003, p. 887

# c[CuL] = 2x10-3 M; scan rate 0.1 V/sec; Epa and Epc are the anodic and

cathodic peaks potentials respectively. E is Epa - Epc in 0.1M LiClO4 inDMF. E1/2 = (Epa+Epc)/2

4.XISHI, T., XIANHONG, Y., QUIAN, C., MINYU, T., Molecules, 8, 2003,p. 4395.SIMNDI, L. I. Dioxygen Activation and Homogeneous CatalyticOxydation; Elsevier: Amsterdam, 19916. LINDER, M.C., GOODE, C., Biochemistry of Copper, Plenium Press,New York, 19917. KIM, J. N., RYU, E. K., Synthetic communication, 261, nr. 1, 1996,p 678. PATWARI, S. B.,BASEER, M. A., VIBHUTE, Y. B., BHUSURE, S. R.,Tetrahedron letters, 44, 2003

hplc exemple

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