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Research ArticleComplex Formation of Nickel(II) and Copper(II) withBarbituric Acid
Naciye Tuumlrkel and M Suat Aksoy
Department of Chemistry Faculty of Arts and Sciences Uludag University 16059 Bursa Turkey
Correspondence should be addressed to Naciye Turkel nturkeluludagedutr
Received 17 December 2013 Accepted 6 January 2014 Published 12 February 2014
Academic Editors Z Aydogmus and I Zhukov
Copyright copy 2014 N Turkel and M S Aksoy This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
Equilibrium studies have been carried out on complex formation of M2+ ions (M=Ni and Cu) with L = barbituric acid (BA) inaqueous solution at 250 plusmn 01∘C and with an ionic strength of 119868 = 010M (KNO
3) in aqueous medium The basicity of the ligand
was also assessed by the determination of the dissociation constants of the ligandThe experimental pH titration data were analyzedwith the help of the BEST computer program in order to evaluate the stability constants of the various species formedThe stabilityconstants of the binary systems decrease in the order of Cu(II)gtNi(II) Distribution diagrams for the species were drawn showingthe concentrations of individual species as a function of pH by the SPE software program
1 Introduction
Organotransition-metal complexes formed with biologicallyactive ligands have attracted great attention in recent yearsStudies of such complexes in biological systems can leadto a better understanding of the roles of these ligandsand can also contribute to the development of metal-basedchemotherapeutic agents Pyrimidine ring-containing com-pounds can be found in nucleic acids various vitaminsand coenzymes and they play an important role in manybiological systems [1 2] In nucleic acids they are related toanticancer chemotherapeutic antimetabolites [3] Pyrimidinemetal complexes have been studied in recent years because oftheir great variety of biological activities such as antimalarialantibacterial antitumoral antiviral activities and so forth[4ndash10] Despite the multitude of coordination complexes ofpyrimidines the organometallic chemistry of these ligandsreceived little attention mostly from Beck and coworkers[11 12]
Barbiturates are the derivatives of barbituric acid (246-trioxypyrimidine) (Scheme 1)These drugs are used formanyreasons such as hypnotics sedatives or anesthetics [13 14]They also affect the motor and sensory functions and they
are used as cures for anxiety epilepsy and other psychi-atric disorders [15 16] The production process of plasticsand pharmaceuticals requires the uses of barbituric acidIntroduced as one of the first medical use of barbituratesbarbital diethylbarbituric acid is known as veronal or diemal[17] The first psychologically active drug barbital or veronalwas introduced in 1903 by E Fischer [18] Only a fewbarbiturates have anticonvulsant properties although manyof them have sedative-hypnotic attributes However mostbarbiturates cause convulsions at large doses Phenobarbital(5 ethyl-5 phenyl barbituric acid) is used for the treat-ment of convulsive disorders [19] 55-Diethylbarbituric acid(H2debarb) is a sedative-hypnotic and even as a discontinued
chemical its low oil water partition coefficient as a result ofbiological processes makes it interesting [18] Because of theirability to coordinate with transition metals through carbonyloxygen and one or both deprotonated oxygen atoms and alsobecause of their wide use in medicine the synthesis of theirmetal complexes has received great interest
Furthermore it has been suggested that the presence ofthe metal ions in biological fluids could have a significanteffect on the therapeutic action of drugs Many diverseapplications of metal species are aimed at understanding the
Hindawi Publishing CorporationISRN Analytical ChemistryVolume 2014 Article ID 243175 5 pageshttpdxdoiorg1011552014243175
2 ISRN Analytical Chemistry
O
O NH
O
NH
Scheme 1 Structure of the barbituric acid (BA)
natural roles ofmetal ions or exploiting the unique propertiesof metal centers in the study of the biology or biochemistryof nucleic acid and nucleic acid constitutes [2]
The literature review indicated that no work has beendone on complex formation equilibria of this ligand inaqueous medium There is only one study [20] of thisligand with Cu(II) and no work on the barbituric acid withNi(II) They studied Cu(II) and Fe(II) complexation withthe barbiturate ion by the solubility method potentiometrictitration spectroscopy and photometry But they decidedthat the barbiturate anion was a monodentate ligand andcalculated that Cubar+ stability constants was log120573
1= 307plusmn
001 by potentiometry [20] So the objective of this workwas to determine the stability constants of barbituric acidcomplexes with Ni(II) and Cu(II) metallic ions
2 Experimental
21 Chemicals Barbituric acid (BA) was obtained fromMerck Chem Co Ni(NO
3)2sdot6H2O was provided by Aldrich
Chem Co and Cu(NO3)2sdot3H2O was provided by Merck
Chem Co All reagents were of analytical quality and wereusedwithout further purification For the solutions CO
2-free
double-distilled deionized water was obtained through theultrawater purification system
22 Titration Procedure Solutions of metal ions (001M)were prepared from Ni(NO
3)2sdot6H2O and Cu(NO
3)2sdot3H2O
received and standardized with ethylenediaminetetraaceticacid (EDTA) [21] HCl stock solution was prepared fromconcentrated HCl and their concentration was determinedwith standardized NaOH All potentiometric titrations werecarried out on solutions in a 100mL double-walled glass ves-sel using titroline automatic titration systemwhich interfacesto a PC with a 10mL syringe a Schott pH combinationelectrode the temperature was controlled at 250 plusmn 01∘C bycirculating water from a constant-temperature bath The cellwas equipped with a magnetic stirrer and a tightly fittingcap which contained three holes for the combined electrodenitrogen gas and automatic burette The emf was measuredunder nitrogen atmosphereThe ligand concentrations variedin 2 times 10minus3ndash6 times 10minus3M The cell was standardized with twoprimary buffers The buffer solutions were pH = 40 andpH = 70 The electrode was calibrated on the minuslog
10[H+]
scale by titration of a 001M HCl solution (adjusted to 119868 =01M by adding KNO
3) with carbonate free 01M NaOH at
25 plusmn 01∘C The electrode slope calculated from the formula
119870 = (119864pH1 minus 119864pH2)(pH2 minus pH1) was close to the Nernstianvalue 5916mV (pHunit)minus1 within gt99 The emf readingswere converted into hydrogen concentration The p119870w ofwater was calculated at ionic strength of 01M to be 1397
The acid dissociation constants of the ligands weredetermined potentiometrically by titrating the ligand (50mL)solution (2 times 10minus3ndash6 times 10minus3M) of constant ionic strength01M adjusted with KNO
3 The stability constants of the
binary complexes were determined by titrating 50mL of asolution mixture of metal(II) (Ni(II) or Cu(II)) (2 times 10minus3M)the ligand (2 times 10minus3ndash6 times 10minus3M) and 01M KNO
3 One
hundred titration points were collected at one titration Alltitrations were performed in a purified N
2atmosphere using
aqueous 01M NaOH as titrantTheoverall stability constants (120573
119901119902119903) are defined as follows
(charges are omitted for simplicity)
119901M + 119902L + 119903H 999445999468 [M119901L119902H119903] (1)
120573119901119902119903=
[M119901L119902H119903]
[M]119901[L]119902[H]119903 (2)
where M is a metal ion L is the ligand H is the protonand 119903 is the respective stoichiometric coefficient Calculationswere performed using the computer program BEST [22] on apersonal computer
The stoichiometries and the stability constants of thecomplexes formed were determined by trying various pos-sible composition models for the system studied The con-centration distribution diagrams were obtained using theprogram SPE [22]
3 Result and Discussion
Although the dissociation constants of barbituric acid havealready been reported we determined them under ourexperimental conditions by potentiometric titration in thepH range 18ndash120 The BEST computer program was usedfor calculations [22] The obtained values are listed in Table 1together with the literature data for comparison A goodagreement with earlier published data for BA is obtained [23]considering the differences in an ionic strengthTheBA formsthree species in aqueous solution denoted by H
2L HL and
L Consider
H2L 999445999468 HLminus +H+ 119870a1 =
[HLminus] [H+][H2L]
(3)
HLminus 999445999468 Lminus +H+ 119870a2 =[Lminus] [H+][HLminus]
(4)
31 Stability Constants of Ni(II)-BA Complexes Potentiomet-ric pH titrations of Ni(II) were performed at 1 1 1 2 and1 3 metalligand molar ratios at 250 plusmn 01∘C in an 010MKNO3ionic medium BA acid (solid) was added to the Ni(II)
solutions with a metalligandmolar ratio of 1 1 1 2 and 1 3Representative potentiometric titration curves for the Ni(II)-BA complexes with 1 1 1 2 and 1 3 stoichiometry are shown
ISRN Analytical Chemistry 3
Table 1 Acid dissociation constants of Barbituric acid (BA) and the stability constants of the Ni(II) Cu(II)-BA complexes (250 plusmn 01∘C119868 = 01MKNO3)
Equilibrium Constant BA Ni(II) Cu(II)
H2L 999445999468HLminus + H+ log119870H2L389 plusmn 004
(378) [23]
HLminus 999445999468 Lminus2 + H+ log119870HL1190 plusmn 004
(1230) [23]
119901M + 119902L + 119903Hminus 999445999468 [M119901L119902H119903]
log120573110
662 plusmn 009 839 plusmn 005
log120573120
1165 plusmn 003 1416 plusmn 006
log120573131
1794 plusmn 004 1920 plusmn 004
02468101214
0 1 2 3 4 5 6 7 8 9 10m
pH
III III IV
Figure 1 Potentiometric pHprofiles for solutions containing (I) BA119879BA = 20 times 10
minus3M and Ni(II) and BA in the ratios (II) 1 1 (119879Ni =20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Ni = 20 times 10
minus3Mand 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Ni = 20 times 10minus3M and
119879Ni = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
in Figure 1 for BA systems togetherwith the titration curve forthe free ligand (BA) Analysis of the complexed ligand curves(Figure 1) indicates that the addition of metal ion to thefree ligand solutions shifts region of the ligand to lower pHvaluesThis shows that complex formation reactions proceedby releasing protons from BA Two inflection points wereobserved at 119898 = 10 and 119898 sim 22 on the titration curves ofthe 1 1 Ni(II)-BA systems (Curve 2 in Figure 1) where 119898 isthe number of moles of base added per mole of the metal(Figure 1) Experimental data has shown that in the 119898 = 0to sim22 the NiL complex forms between pH = 60ndash110 BAligand acts as a bidentate chelating ligand via the negativelycharged imino N atom and one of the carbonyl O atomsadjacent to the imino N atom
The potentiometric titrations of the 1 2 Ni(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 18 and 119898 = 38 The titration of these protons ineach of these systems indicates that the NiL
2complex forms
graduallyThe second BAwas bound as the same the first BAThe potentiometric titrations of the 1 3 Ni(II)-BA sys-
tems were carried out under the same experimental condi-tions The titration of these protons in each of these systemsindicates that the NiL
3H complex forms gradually But in the
third BA molecule it was bound only once via the negativelycharged imino N atom or one of the carbonyl O atoms In
the 1 3 molar ratio potentiometric titrations the stabilityconstants of the complexes NiL NiL
2 and NiL
3H were
calculated by the BEST computer program [22] The stabilityconstants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion present sim2 times 10minus3 M set at 100 InFigure 3 the species NiL
3H for the system BA and metal ion
Ni(II) reaches a maximum of 100 at pH 100 The secondspecies NiL
2reaches a maximum of 10 at pH 70minus120 and
NiL complex species in the mole ratio of 1 moles of ligand toone mole metal presents a maximum of 70 near pH 60
32 Stability Constants of Cu(II)-BA Complexes The poten-tiometric titrations of the Cu(II)BA systems were performedat 250plusmn01∘C in an 010MKNO
3ionicmedium BA acid was
added to the Cu(II) solutions with a molar ratio of 1 1 1 2and 1 3 Two inflection points were observed at 119898 = 10 and119898 sim 22 on the titration curves of the 1 1 Cu(II)-BA systems(Curve 2 in Figure 2) where 119898 is the number of moles ofbase added per mole of the metal (Figure 2) In addition thetitration curve of the Cu(II) complex is different from that ofthe free BA curve Experimental data has shown that in the119898 = 0 to sim22 buffer zone the CuL complex forms betweenpH = 60ndash110
The potentiometric titrations of the 1 2 Cu(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 30 and 119898 = 50 The titration of these protons ineach of these systems indicates that the CuL
2complex forms
graduallyThe potentiometric titrations of the 1 3 Cu(II)-BA sys-
tems were carried out under the same experimental condi-tions In these curves two inflection points were observed at119898 = 40 and 119898 = 50 The titration of these protons in eachof these systems indicates that the CuL
3H complex forms
gradually In the 1 3molar ratio potentiometric titrations thestability constants of the complexes CuL CuL
2 and CuL
3H
were calculated by the BEST computer program [22] Thestability constants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion presents sim2 times 10minus3M set at 100
4 ISRN Analytical Chemistry
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6 7 8m
pH
I III
II IV
Figure 2 Potentiometric pH profiles for solutions containing (I)BA 119879BA = 20 times 10
minus3M and Cu(II) and BA in the ratios (II) 1 1(119879Cu = 20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Cu = 20 times
10minus3M and 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Cu = 20 times 10minus3M
and 119879BA = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
Ni
NiL
NiL3H
NiL2
a(
)
Figure 3 Species distribution curves of the metal ion Ni(II) andthe BA as a function of pH for a solution initially containing 119879Ni =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of themetal set at 100 NiL NiL2 and NiL
3H are
the complexed species with one two and three ligand molecules
In Figure 4 the species CuL3H for the system BA and metal
ion Cu(II) reaches a maximum of 90 at pH 120The secondspecies CuL
2reaches a maximum of 60 at pH 60minus120 and
the CuL complex species in the ratio of 1 moles of ligand toone mole metal presents a maximum of 90 near pH 40ndash100
It can be observed that the stability constants of theNi(II)-BA complexes are lower than Cu(II)-BA complexes
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
CuCuL
CuL3H
CuL2a(
)
Figure 4 Species distribution curves of the metal ion Cu(II) andthe BA as a function of pH for a solution initially containing 119879Cu =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of the metal set at 100 CuL and CuL2 CuL
3H
are the complexed species with one two and three ligandmolecules
Acknowledgment
The authors thank the Research Fund of Uludag Universityfor the financial support given to the research projects(Project no UAP(F)-201170)
References
[1] F Hueso-Urena N A Illan-Cabeza M N Moreno-CarreteroJ M Martınez-Martos and M J Ramırez-Exposito ldquoSynthesisand spectroscopic studies on the new Schiff base derived fromthe 1 2 condensation of 26-diformyl-4-methylphenol with 5-aminouracil (BDF5AU) and its transition metal complexesinfluence on biologically active peptides-regulating aminopep-tidasesrdquo Journal of Inorganic Biochemistry vol 94 no 4 pp326ndash334 2003
[2] M S Refat S A El-Korashy and A S Ahmed ldquoA convenientmethod for the preparation of barbituric and thiobarbituric acidtransition metal complexesrdquo Spectrochimica Acta A vol 71 no3 pp 1084ndash1094 2008
[3] A Tsunoda M Shibusawa Y Tsunoda N Yasuda K Nakaoand M Kusano ldquoA model for sensitivity determination ofanticancer agents against chemically-induced colon cancer inratsrdquo Anticancer Research vol 14 no 6B pp 2637ndash2642 1994
[4] E S Raper ldquoComplexes of heterocyclic thione donorsrdquo Coordi-nation Chemistry Reviews vol 61 pp 115ndash184 1985
[5] J S Casas E E Castellano M D Couce et al ldquoA gold(I)complex with a vitamin K
3derivative characterization and
antitumoral activityrdquo Journal of Inorganic Biochemistry vol 100no 11 pp 1858ndash1860 2006
[6] M J M Campbell ldquoTransition metal complexes of thiosemi-carbazide and thiosemicarbazonesrdquo Coordination ChemistryReviews vol 15 no 2-3 pp 279ndash319 1975
[7] M C Rodriguez-Arguelles M B Ferrari G G Fava et alldquo26-Diacetylpyridine bis(thiosemicarbazones) zinc complexessynthesis structure and biological activityrdquo Journal of InorganicBiochemistry vol 58 no 3 pp 157ndash175 1995
[8] J S Casas M S Garcıa-Tasende C Maichle-Mossmer et alldquoSynthesis structure and spectroscopic properties of acetato(dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)-tin(IV) acetic acid solvate [SnMe
2(PyTSC)(OAc)]HOAc
Comparison of its biological activity with that of some struc-
ISRN Analytical Chemistry 5
turally related diorganotin(IV) bis (thiosemicarbazonates)rdquoJournal of Inorganic Biochemistry vol 62 no 1 pp 41ndash55 1996
[9] M B Ferrari G G Fava P Tarasconi R Albertini S Pinelliand R Starcich ldquoSynthesis spectroscopic and structural char-acterization and biological activity of aquachloro(pyridoxalthiosemicarbazone) copper(II) chloriderdquo Journal of InorganicBiochemistry vol 53 no 1 pp 13ndash25 1994
[10] U Koch B Attenni S Malancona et al ldquo2-(2-Thienyl)-56-dihydroxy-4-carboxypyrimidines as inhibitors of the hepatitisC virus NS5B polymerase discovery SAR modeling andmutagenesisrdquo Journal of Medicinal Chemistry vol 49 no 5 pp1693ndash1705 2006
[11] W Beck andN Kottmair ldquoNeue UbergangsmetallkomplexemitNuclein-Basen und Nucleosidenrdquo Chemische Berichte vol 109no 3 pp 970ndash993 1976
[12] N Kottmair and W Beck ldquoTungsten carbonyl complexes of2101584031015840-O-isopropylideneguanosine and 6-mercaptopurinerdquo Inor-ganica Chimica Acta vol 34 pp 137ndash144 1979
[13] A Ashnagar N G Naseri and B Sheeri ldquoNovel synthesis ofbarbituratesrdquo Chinese Journal of Chemistry vol 25 no 3 pp382ndash384 2007
[14] J N Delgado W A Remers and J B Lippincott Eds Wilsonand Gisvoldrsquos Textbook of Organic Medicinal PharmaceuticalChemistry Williams amp Wilkins Philadelphia Pa USA 9thedition 1991
[15] J-L Fillaut I de Los Rios D Masi A Romerosa F Zanobiniand M Peruzzini ldquoSynthesis and structural characterizationof (carbene)ruthenium complexes binding nucleobasesrdquo Euro-pean Journal of Inorganic Chemistry vol 2002 no 4 pp 935ndash942 2002
[16] O Temiz-Arpaci A Ozdemir I Yalcin I Yildiz E Aki-Sener and N Altanlar ldquoSynthesis and antimicrobial activityof some 5-[2-(morpholin-4-yl) acetamido] andor 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substitutedphenyl)benzoxazolesrdquo Archiv der Pharmazie vol 338 no 2-3pp 105ndash111 2005
[17] T W G Solomons and C B Fryhle Organic Chemistry JohnWiley amp Sons Hoboken NJ USA 9th edition 2008
[18] J H Block and J M Beale Wilson and Gisvoldrsquos Textbook ofOrganic Medicinal and Pharmaceutical Chemistry LippincottWilliams ampWilkins Philadelphia Pa USA 11th edition 2004
[19] W O Foye T L Lemke and D A Williams Principles ofMedicinal Chemistry Williams amp Wilkins Philadelphia PaUSA 4th edition 1995
[20] N M Korotchenko and N A Skorik ldquoInteraction of copper(II)and iron(III) with barbituric acidrdquo Russian Journal of InorganicChemistry vol 45 no 12 pp 1945ndash1948 2000
[21] G Schwarzenbach and H Flaschka Complexometric TitrationsInterscience New York NY USA 1969
[22] A E Martell and R J Motekaitis Determination and Use ofStability Constants Wiley-VCH New York NY USA 1989
[23] M-J Blais O Enea and G Berthon ldquoRelations structure-reactivite grandeurs thermodynamiques de protonationdrsquohrsquoetrsquoerocycles satures et non saturesrdquo Thermochimica Actavol 20 no 3 pp 335ndash345 1977
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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CatalystsJournal of
2 ISRN Analytical Chemistry
O
O NH
O
NH
Scheme 1 Structure of the barbituric acid (BA)
natural roles ofmetal ions or exploiting the unique propertiesof metal centers in the study of the biology or biochemistryof nucleic acid and nucleic acid constitutes [2]
The literature review indicated that no work has beendone on complex formation equilibria of this ligand inaqueous medium There is only one study [20] of thisligand with Cu(II) and no work on the barbituric acid withNi(II) They studied Cu(II) and Fe(II) complexation withthe barbiturate ion by the solubility method potentiometrictitration spectroscopy and photometry But they decidedthat the barbiturate anion was a monodentate ligand andcalculated that Cubar+ stability constants was log120573
1= 307plusmn
001 by potentiometry [20] So the objective of this workwas to determine the stability constants of barbituric acidcomplexes with Ni(II) and Cu(II) metallic ions
2 Experimental
21 Chemicals Barbituric acid (BA) was obtained fromMerck Chem Co Ni(NO
3)2sdot6H2O was provided by Aldrich
Chem Co and Cu(NO3)2sdot3H2O was provided by Merck
Chem Co All reagents were of analytical quality and wereusedwithout further purification For the solutions CO
2-free
double-distilled deionized water was obtained through theultrawater purification system
22 Titration Procedure Solutions of metal ions (001M)were prepared from Ni(NO
3)2sdot6H2O and Cu(NO
3)2sdot3H2O
received and standardized with ethylenediaminetetraaceticacid (EDTA) [21] HCl stock solution was prepared fromconcentrated HCl and their concentration was determinedwith standardized NaOH All potentiometric titrations werecarried out on solutions in a 100mL double-walled glass ves-sel using titroline automatic titration systemwhich interfacesto a PC with a 10mL syringe a Schott pH combinationelectrode the temperature was controlled at 250 plusmn 01∘C bycirculating water from a constant-temperature bath The cellwas equipped with a magnetic stirrer and a tightly fittingcap which contained three holes for the combined electrodenitrogen gas and automatic burette The emf was measuredunder nitrogen atmosphereThe ligand concentrations variedin 2 times 10minus3ndash6 times 10minus3M The cell was standardized with twoprimary buffers The buffer solutions were pH = 40 andpH = 70 The electrode was calibrated on the minuslog
10[H+]
scale by titration of a 001M HCl solution (adjusted to 119868 =01M by adding KNO
3) with carbonate free 01M NaOH at
25 plusmn 01∘C The electrode slope calculated from the formula
119870 = (119864pH1 minus 119864pH2)(pH2 minus pH1) was close to the Nernstianvalue 5916mV (pHunit)minus1 within gt99 The emf readingswere converted into hydrogen concentration The p119870w ofwater was calculated at ionic strength of 01M to be 1397
The acid dissociation constants of the ligands weredetermined potentiometrically by titrating the ligand (50mL)solution (2 times 10minus3ndash6 times 10minus3M) of constant ionic strength01M adjusted with KNO
3 The stability constants of the
binary complexes were determined by titrating 50mL of asolution mixture of metal(II) (Ni(II) or Cu(II)) (2 times 10minus3M)the ligand (2 times 10minus3ndash6 times 10minus3M) and 01M KNO
3 One
hundred titration points were collected at one titration Alltitrations were performed in a purified N
2atmosphere using
aqueous 01M NaOH as titrantTheoverall stability constants (120573
119901119902119903) are defined as follows
(charges are omitted for simplicity)
119901M + 119902L + 119903H 999445999468 [M119901L119902H119903] (1)
120573119901119902119903=
[M119901L119902H119903]
[M]119901[L]119902[H]119903 (2)
where M is a metal ion L is the ligand H is the protonand 119903 is the respective stoichiometric coefficient Calculationswere performed using the computer program BEST [22] on apersonal computer
The stoichiometries and the stability constants of thecomplexes formed were determined by trying various pos-sible composition models for the system studied The con-centration distribution diagrams were obtained using theprogram SPE [22]
3 Result and Discussion
Although the dissociation constants of barbituric acid havealready been reported we determined them under ourexperimental conditions by potentiometric titration in thepH range 18ndash120 The BEST computer program was usedfor calculations [22] The obtained values are listed in Table 1together with the literature data for comparison A goodagreement with earlier published data for BA is obtained [23]considering the differences in an ionic strengthTheBA formsthree species in aqueous solution denoted by H
2L HL and
L Consider
H2L 999445999468 HLminus +H+ 119870a1 =
[HLminus] [H+][H2L]
(3)
HLminus 999445999468 Lminus +H+ 119870a2 =[Lminus] [H+][HLminus]
(4)
31 Stability Constants of Ni(II)-BA Complexes Potentiomet-ric pH titrations of Ni(II) were performed at 1 1 1 2 and1 3 metalligand molar ratios at 250 plusmn 01∘C in an 010MKNO3ionic medium BA acid (solid) was added to the Ni(II)
solutions with a metalligandmolar ratio of 1 1 1 2 and 1 3Representative potentiometric titration curves for the Ni(II)-BA complexes with 1 1 1 2 and 1 3 stoichiometry are shown
ISRN Analytical Chemistry 3
Table 1 Acid dissociation constants of Barbituric acid (BA) and the stability constants of the Ni(II) Cu(II)-BA complexes (250 plusmn 01∘C119868 = 01MKNO3)
Equilibrium Constant BA Ni(II) Cu(II)
H2L 999445999468HLminus + H+ log119870H2L389 plusmn 004
(378) [23]
HLminus 999445999468 Lminus2 + H+ log119870HL1190 plusmn 004
(1230) [23]
119901M + 119902L + 119903Hminus 999445999468 [M119901L119902H119903]
log120573110
662 plusmn 009 839 plusmn 005
log120573120
1165 plusmn 003 1416 plusmn 006
log120573131
1794 plusmn 004 1920 plusmn 004
02468101214
0 1 2 3 4 5 6 7 8 9 10m
pH
III III IV
Figure 1 Potentiometric pHprofiles for solutions containing (I) BA119879BA = 20 times 10
minus3M and Ni(II) and BA in the ratios (II) 1 1 (119879Ni =20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Ni = 20 times 10
minus3Mand 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Ni = 20 times 10minus3M and
119879Ni = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
in Figure 1 for BA systems togetherwith the titration curve forthe free ligand (BA) Analysis of the complexed ligand curves(Figure 1) indicates that the addition of metal ion to thefree ligand solutions shifts region of the ligand to lower pHvaluesThis shows that complex formation reactions proceedby releasing protons from BA Two inflection points wereobserved at 119898 = 10 and 119898 sim 22 on the titration curves ofthe 1 1 Ni(II)-BA systems (Curve 2 in Figure 1) where 119898 isthe number of moles of base added per mole of the metal(Figure 1) Experimental data has shown that in the 119898 = 0to sim22 the NiL complex forms between pH = 60ndash110 BAligand acts as a bidentate chelating ligand via the negativelycharged imino N atom and one of the carbonyl O atomsadjacent to the imino N atom
The potentiometric titrations of the 1 2 Ni(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 18 and 119898 = 38 The titration of these protons ineach of these systems indicates that the NiL
2complex forms
graduallyThe second BAwas bound as the same the first BAThe potentiometric titrations of the 1 3 Ni(II)-BA sys-
tems were carried out under the same experimental condi-tions The titration of these protons in each of these systemsindicates that the NiL
3H complex forms gradually But in the
third BA molecule it was bound only once via the negativelycharged imino N atom or one of the carbonyl O atoms In
the 1 3 molar ratio potentiometric titrations the stabilityconstants of the complexes NiL NiL
2 and NiL
3H were
calculated by the BEST computer program [22] The stabilityconstants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion present sim2 times 10minus3 M set at 100 InFigure 3 the species NiL
3H for the system BA and metal ion
Ni(II) reaches a maximum of 100 at pH 100 The secondspecies NiL
2reaches a maximum of 10 at pH 70minus120 and
NiL complex species in the mole ratio of 1 moles of ligand toone mole metal presents a maximum of 70 near pH 60
32 Stability Constants of Cu(II)-BA Complexes The poten-tiometric titrations of the Cu(II)BA systems were performedat 250plusmn01∘C in an 010MKNO
3ionicmedium BA acid was
added to the Cu(II) solutions with a molar ratio of 1 1 1 2and 1 3 Two inflection points were observed at 119898 = 10 and119898 sim 22 on the titration curves of the 1 1 Cu(II)-BA systems(Curve 2 in Figure 2) where 119898 is the number of moles ofbase added per mole of the metal (Figure 2) In addition thetitration curve of the Cu(II) complex is different from that ofthe free BA curve Experimental data has shown that in the119898 = 0 to sim22 buffer zone the CuL complex forms betweenpH = 60ndash110
The potentiometric titrations of the 1 2 Cu(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 30 and 119898 = 50 The titration of these protons ineach of these systems indicates that the CuL
2complex forms
graduallyThe potentiometric titrations of the 1 3 Cu(II)-BA sys-
tems were carried out under the same experimental condi-tions In these curves two inflection points were observed at119898 = 40 and 119898 = 50 The titration of these protons in eachof these systems indicates that the CuL
3H complex forms
gradually In the 1 3molar ratio potentiometric titrations thestability constants of the complexes CuL CuL
2 and CuL
3H
were calculated by the BEST computer program [22] Thestability constants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion presents sim2 times 10minus3M set at 100
4 ISRN Analytical Chemistry
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6 7 8m
pH
I III
II IV
Figure 2 Potentiometric pH profiles for solutions containing (I)BA 119879BA = 20 times 10
minus3M and Cu(II) and BA in the ratios (II) 1 1(119879Cu = 20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Cu = 20 times
10minus3M and 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Cu = 20 times 10minus3M
and 119879BA = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
Ni
NiL
NiL3H
NiL2
a(
)
Figure 3 Species distribution curves of the metal ion Ni(II) andthe BA as a function of pH for a solution initially containing 119879Ni =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of themetal set at 100 NiL NiL2 and NiL
3H are
the complexed species with one two and three ligand molecules
In Figure 4 the species CuL3H for the system BA and metal
ion Cu(II) reaches a maximum of 90 at pH 120The secondspecies CuL
2reaches a maximum of 60 at pH 60minus120 and
the CuL complex species in the ratio of 1 moles of ligand toone mole metal presents a maximum of 90 near pH 40ndash100
It can be observed that the stability constants of theNi(II)-BA complexes are lower than Cu(II)-BA complexes
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
CuCuL
CuL3H
CuL2a(
)
Figure 4 Species distribution curves of the metal ion Cu(II) andthe BA as a function of pH for a solution initially containing 119879Cu =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of the metal set at 100 CuL and CuL2 CuL
3H
are the complexed species with one two and three ligandmolecules
Acknowledgment
The authors thank the Research Fund of Uludag Universityfor the financial support given to the research projects(Project no UAP(F)-201170)
References
[1] F Hueso-Urena N A Illan-Cabeza M N Moreno-CarreteroJ M Martınez-Martos and M J Ramırez-Exposito ldquoSynthesisand spectroscopic studies on the new Schiff base derived fromthe 1 2 condensation of 26-diformyl-4-methylphenol with 5-aminouracil (BDF5AU) and its transition metal complexesinfluence on biologically active peptides-regulating aminopep-tidasesrdquo Journal of Inorganic Biochemistry vol 94 no 4 pp326ndash334 2003
[2] M S Refat S A El-Korashy and A S Ahmed ldquoA convenientmethod for the preparation of barbituric and thiobarbituric acidtransition metal complexesrdquo Spectrochimica Acta A vol 71 no3 pp 1084ndash1094 2008
[3] A Tsunoda M Shibusawa Y Tsunoda N Yasuda K Nakaoand M Kusano ldquoA model for sensitivity determination ofanticancer agents against chemically-induced colon cancer inratsrdquo Anticancer Research vol 14 no 6B pp 2637ndash2642 1994
[4] E S Raper ldquoComplexes of heterocyclic thione donorsrdquo Coordi-nation Chemistry Reviews vol 61 pp 115ndash184 1985
[5] J S Casas E E Castellano M D Couce et al ldquoA gold(I)complex with a vitamin K
3derivative characterization and
antitumoral activityrdquo Journal of Inorganic Biochemistry vol 100no 11 pp 1858ndash1860 2006
[6] M J M Campbell ldquoTransition metal complexes of thiosemi-carbazide and thiosemicarbazonesrdquo Coordination ChemistryReviews vol 15 no 2-3 pp 279ndash319 1975
[7] M C Rodriguez-Arguelles M B Ferrari G G Fava et alldquo26-Diacetylpyridine bis(thiosemicarbazones) zinc complexessynthesis structure and biological activityrdquo Journal of InorganicBiochemistry vol 58 no 3 pp 157ndash175 1995
[8] J S Casas M S Garcıa-Tasende C Maichle-Mossmer et alldquoSynthesis structure and spectroscopic properties of acetato(dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)-tin(IV) acetic acid solvate [SnMe
2(PyTSC)(OAc)]HOAc
Comparison of its biological activity with that of some struc-
ISRN Analytical Chemistry 5
turally related diorganotin(IV) bis (thiosemicarbazonates)rdquoJournal of Inorganic Biochemistry vol 62 no 1 pp 41ndash55 1996
[9] M B Ferrari G G Fava P Tarasconi R Albertini S Pinelliand R Starcich ldquoSynthesis spectroscopic and structural char-acterization and biological activity of aquachloro(pyridoxalthiosemicarbazone) copper(II) chloriderdquo Journal of InorganicBiochemistry vol 53 no 1 pp 13ndash25 1994
[10] U Koch B Attenni S Malancona et al ldquo2-(2-Thienyl)-56-dihydroxy-4-carboxypyrimidines as inhibitors of the hepatitisC virus NS5B polymerase discovery SAR modeling andmutagenesisrdquo Journal of Medicinal Chemistry vol 49 no 5 pp1693ndash1705 2006
[11] W Beck andN Kottmair ldquoNeue UbergangsmetallkomplexemitNuclein-Basen und Nucleosidenrdquo Chemische Berichte vol 109no 3 pp 970ndash993 1976
[12] N Kottmair and W Beck ldquoTungsten carbonyl complexes of2101584031015840-O-isopropylideneguanosine and 6-mercaptopurinerdquo Inor-ganica Chimica Acta vol 34 pp 137ndash144 1979
[13] A Ashnagar N G Naseri and B Sheeri ldquoNovel synthesis ofbarbituratesrdquo Chinese Journal of Chemistry vol 25 no 3 pp382ndash384 2007
[14] J N Delgado W A Remers and J B Lippincott Eds Wilsonand Gisvoldrsquos Textbook of Organic Medicinal PharmaceuticalChemistry Williams amp Wilkins Philadelphia Pa USA 9thedition 1991
[15] J-L Fillaut I de Los Rios D Masi A Romerosa F Zanobiniand M Peruzzini ldquoSynthesis and structural characterizationof (carbene)ruthenium complexes binding nucleobasesrdquo Euro-pean Journal of Inorganic Chemistry vol 2002 no 4 pp 935ndash942 2002
[16] O Temiz-Arpaci A Ozdemir I Yalcin I Yildiz E Aki-Sener and N Altanlar ldquoSynthesis and antimicrobial activityof some 5-[2-(morpholin-4-yl) acetamido] andor 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substitutedphenyl)benzoxazolesrdquo Archiv der Pharmazie vol 338 no 2-3pp 105ndash111 2005
[17] T W G Solomons and C B Fryhle Organic Chemistry JohnWiley amp Sons Hoboken NJ USA 9th edition 2008
[18] J H Block and J M Beale Wilson and Gisvoldrsquos Textbook ofOrganic Medicinal and Pharmaceutical Chemistry LippincottWilliams ampWilkins Philadelphia Pa USA 11th edition 2004
[19] W O Foye T L Lemke and D A Williams Principles ofMedicinal Chemistry Williams amp Wilkins Philadelphia PaUSA 4th edition 1995
[20] N M Korotchenko and N A Skorik ldquoInteraction of copper(II)and iron(III) with barbituric acidrdquo Russian Journal of InorganicChemistry vol 45 no 12 pp 1945ndash1948 2000
[21] G Schwarzenbach and H Flaschka Complexometric TitrationsInterscience New York NY USA 1969
[22] A E Martell and R J Motekaitis Determination and Use ofStability Constants Wiley-VCH New York NY USA 1989
[23] M-J Blais O Enea and G Berthon ldquoRelations structure-reactivite grandeurs thermodynamiques de protonationdrsquohrsquoetrsquoerocycles satures et non saturesrdquo Thermochimica Actavol 20 no 3 pp 335ndash345 1977
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ISRN Analytical Chemistry 3
Table 1 Acid dissociation constants of Barbituric acid (BA) and the stability constants of the Ni(II) Cu(II)-BA complexes (250 plusmn 01∘C119868 = 01MKNO3)
Equilibrium Constant BA Ni(II) Cu(II)
H2L 999445999468HLminus + H+ log119870H2L389 plusmn 004
(378) [23]
HLminus 999445999468 Lminus2 + H+ log119870HL1190 plusmn 004
(1230) [23]
119901M + 119902L + 119903Hminus 999445999468 [M119901L119902H119903]
log120573110
662 plusmn 009 839 plusmn 005
log120573120
1165 plusmn 003 1416 plusmn 006
log120573131
1794 plusmn 004 1920 plusmn 004
02468101214
0 1 2 3 4 5 6 7 8 9 10m
pH
III III IV
Figure 1 Potentiometric pHprofiles for solutions containing (I) BA119879BA = 20 times 10
minus3M and Ni(II) and BA in the ratios (II) 1 1 (119879Ni =20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Ni = 20 times 10
minus3Mand 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Ni = 20 times 10minus3M and
119879Ni = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
in Figure 1 for BA systems togetherwith the titration curve forthe free ligand (BA) Analysis of the complexed ligand curves(Figure 1) indicates that the addition of metal ion to thefree ligand solutions shifts region of the ligand to lower pHvaluesThis shows that complex formation reactions proceedby releasing protons from BA Two inflection points wereobserved at 119898 = 10 and 119898 sim 22 on the titration curves ofthe 1 1 Ni(II)-BA systems (Curve 2 in Figure 1) where 119898 isthe number of moles of base added per mole of the metal(Figure 1) Experimental data has shown that in the 119898 = 0to sim22 the NiL complex forms between pH = 60ndash110 BAligand acts as a bidentate chelating ligand via the negativelycharged imino N atom and one of the carbonyl O atomsadjacent to the imino N atom
The potentiometric titrations of the 1 2 Ni(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 18 and 119898 = 38 The titration of these protons ineach of these systems indicates that the NiL
2complex forms
graduallyThe second BAwas bound as the same the first BAThe potentiometric titrations of the 1 3 Ni(II)-BA sys-
tems were carried out under the same experimental condi-tions The titration of these protons in each of these systemsindicates that the NiL
3H complex forms gradually But in the
third BA molecule it was bound only once via the negativelycharged imino N atom or one of the carbonyl O atoms In
the 1 3 molar ratio potentiometric titrations the stabilityconstants of the complexes NiL NiL
2 and NiL
3H were
calculated by the BEST computer program [22] The stabilityconstants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion present sim2 times 10minus3 M set at 100 InFigure 3 the species NiL
3H for the system BA and metal ion
Ni(II) reaches a maximum of 100 at pH 100 The secondspecies NiL
2reaches a maximum of 10 at pH 70minus120 and
NiL complex species in the mole ratio of 1 moles of ligand toone mole metal presents a maximum of 70 near pH 60
32 Stability Constants of Cu(II)-BA Complexes The poten-tiometric titrations of the Cu(II)BA systems were performedat 250plusmn01∘C in an 010MKNO
3ionicmedium BA acid was
added to the Cu(II) solutions with a molar ratio of 1 1 1 2and 1 3 Two inflection points were observed at 119898 = 10 and119898 sim 22 on the titration curves of the 1 1 Cu(II)-BA systems(Curve 2 in Figure 2) where 119898 is the number of moles ofbase added per mole of the metal (Figure 2) In addition thetitration curve of the Cu(II) complex is different from that ofthe free BA curve Experimental data has shown that in the119898 = 0 to sim22 buffer zone the CuL complex forms betweenpH = 60ndash110
The potentiometric titrations of the 1 2 Cu(II)-BA sys-tems were carried out under the same experimental condi-tions In these curves two inflection points were observedat 119898 = 30 and 119898 = 50 The titration of these protons ineach of these systems indicates that the CuL
2complex forms
graduallyThe potentiometric titrations of the 1 3 Cu(II)-BA sys-
tems were carried out under the same experimental condi-tions In these curves two inflection points were observed at119898 = 40 and 119898 = 50 The titration of these protons in eachof these systems indicates that the CuL
3H complex forms
gradually In the 1 3molar ratio potentiometric titrations thestability constants of the complexes CuL CuL
2 and CuL
3H
were calculated by the BEST computer program [22] Thestability constants of their complexes are given in Table 1
The distribution diagrams were drawn in the titrationwhere the metal to ligand mole ratio was 1 3 They wereobtained with the aid of SPE program [22] and the concen-tration of total metal ion presents sim2 times 10minus3M set at 100
4 ISRN Analytical Chemistry
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6 7 8m
pH
I III
II IV
Figure 2 Potentiometric pH profiles for solutions containing (I)BA 119879BA = 20 times 10
minus3M and Cu(II) and BA in the ratios (II) 1 1(119879Cu = 20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Cu = 20 times
10minus3M and 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Cu = 20 times 10minus3M
and 119879BA = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
Ni
NiL
NiL3H
NiL2
a(
)
Figure 3 Species distribution curves of the metal ion Ni(II) andthe BA as a function of pH for a solution initially containing 119879Ni =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of themetal set at 100 NiL NiL2 and NiL
3H are
the complexed species with one two and three ligand molecules
In Figure 4 the species CuL3H for the system BA and metal
ion Cu(II) reaches a maximum of 90 at pH 120The secondspecies CuL
2reaches a maximum of 60 at pH 60minus120 and
the CuL complex species in the ratio of 1 moles of ligand toone mole metal presents a maximum of 90 near pH 40ndash100
It can be observed that the stability constants of theNi(II)-BA complexes are lower than Cu(II)-BA complexes
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
CuCuL
CuL3H
CuL2a(
)
Figure 4 Species distribution curves of the metal ion Cu(II) andthe BA as a function of pH for a solution initially containing 119879Cu =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of the metal set at 100 CuL and CuL2 CuL
3H
are the complexed species with one two and three ligandmolecules
Acknowledgment
The authors thank the Research Fund of Uludag Universityfor the financial support given to the research projects(Project no UAP(F)-201170)
References
[1] F Hueso-Urena N A Illan-Cabeza M N Moreno-CarreteroJ M Martınez-Martos and M J Ramırez-Exposito ldquoSynthesisand spectroscopic studies on the new Schiff base derived fromthe 1 2 condensation of 26-diformyl-4-methylphenol with 5-aminouracil (BDF5AU) and its transition metal complexesinfluence on biologically active peptides-regulating aminopep-tidasesrdquo Journal of Inorganic Biochemistry vol 94 no 4 pp326ndash334 2003
[2] M S Refat S A El-Korashy and A S Ahmed ldquoA convenientmethod for the preparation of barbituric and thiobarbituric acidtransition metal complexesrdquo Spectrochimica Acta A vol 71 no3 pp 1084ndash1094 2008
[3] A Tsunoda M Shibusawa Y Tsunoda N Yasuda K Nakaoand M Kusano ldquoA model for sensitivity determination ofanticancer agents against chemically-induced colon cancer inratsrdquo Anticancer Research vol 14 no 6B pp 2637ndash2642 1994
[4] E S Raper ldquoComplexes of heterocyclic thione donorsrdquo Coordi-nation Chemistry Reviews vol 61 pp 115ndash184 1985
[5] J S Casas E E Castellano M D Couce et al ldquoA gold(I)complex with a vitamin K
3derivative characterization and
antitumoral activityrdquo Journal of Inorganic Biochemistry vol 100no 11 pp 1858ndash1860 2006
[6] M J M Campbell ldquoTransition metal complexes of thiosemi-carbazide and thiosemicarbazonesrdquo Coordination ChemistryReviews vol 15 no 2-3 pp 279ndash319 1975
[7] M C Rodriguez-Arguelles M B Ferrari G G Fava et alldquo26-Diacetylpyridine bis(thiosemicarbazones) zinc complexessynthesis structure and biological activityrdquo Journal of InorganicBiochemistry vol 58 no 3 pp 157ndash175 1995
[8] J S Casas M S Garcıa-Tasende C Maichle-Mossmer et alldquoSynthesis structure and spectroscopic properties of acetato(dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)-tin(IV) acetic acid solvate [SnMe
2(PyTSC)(OAc)]HOAc
Comparison of its biological activity with that of some struc-
ISRN Analytical Chemistry 5
turally related diorganotin(IV) bis (thiosemicarbazonates)rdquoJournal of Inorganic Biochemistry vol 62 no 1 pp 41ndash55 1996
[9] M B Ferrari G G Fava P Tarasconi R Albertini S Pinelliand R Starcich ldquoSynthesis spectroscopic and structural char-acterization and biological activity of aquachloro(pyridoxalthiosemicarbazone) copper(II) chloriderdquo Journal of InorganicBiochemistry vol 53 no 1 pp 13ndash25 1994
[10] U Koch B Attenni S Malancona et al ldquo2-(2-Thienyl)-56-dihydroxy-4-carboxypyrimidines as inhibitors of the hepatitisC virus NS5B polymerase discovery SAR modeling andmutagenesisrdquo Journal of Medicinal Chemistry vol 49 no 5 pp1693ndash1705 2006
[11] W Beck andN Kottmair ldquoNeue UbergangsmetallkomplexemitNuclein-Basen und Nucleosidenrdquo Chemische Berichte vol 109no 3 pp 970ndash993 1976
[12] N Kottmair and W Beck ldquoTungsten carbonyl complexes of2101584031015840-O-isopropylideneguanosine and 6-mercaptopurinerdquo Inor-ganica Chimica Acta vol 34 pp 137ndash144 1979
[13] A Ashnagar N G Naseri and B Sheeri ldquoNovel synthesis ofbarbituratesrdquo Chinese Journal of Chemistry vol 25 no 3 pp382ndash384 2007
[14] J N Delgado W A Remers and J B Lippincott Eds Wilsonand Gisvoldrsquos Textbook of Organic Medicinal PharmaceuticalChemistry Williams amp Wilkins Philadelphia Pa USA 9thedition 1991
[15] J-L Fillaut I de Los Rios D Masi A Romerosa F Zanobiniand M Peruzzini ldquoSynthesis and structural characterizationof (carbene)ruthenium complexes binding nucleobasesrdquo Euro-pean Journal of Inorganic Chemistry vol 2002 no 4 pp 935ndash942 2002
[16] O Temiz-Arpaci A Ozdemir I Yalcin I Yildiz E Aki-Sener and N Altanlar ldquoSynthesis and antimicrobial activityof some 5-[2-(morpholin-4-yl) acetamido] andor 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substitutedphenyl)benzoxazolesrdquo Archiv der Pharmazie vol 338 no 2-3pp 105ndash111 2005
[17] T W G Solomons and C B Fryhle Organic Chemistry JohnWiley amp Sons Hoboken NJ USA 9th edition 2008
[18] J H Block and J M Beale Wilson and Gisvoldrsquos Textbook ofOrganic Medicinal and Pharmaceutical Chemistry LippincottWilliams ampWilkins Philadelphia Pa USA 11th edition 2004
[19] W O Foye T L Lemke and D A Williams Principles ofMedicinal Chemistry Williams amp Wilkins Philadelphia PaUSA 4th edition 1995
[20] N M Korotchenko and N A Skorik ldquoInteraction of copper(II)and iron(III) with barbituric acidrdquo Russian Journal of InorganicChemistry vol 45 no 12 pp 1945ndash1948 2000
[21] G Schwarzenbach and H Flaschka Complexometric TitrationsInterscience New York NY USA 1969
[22] A E Martell and R J Motekaitis Determination and Use ofStability Constants Wiley-VCH New York NY USA 1989
[23] M-J Blais O Enea and G Berthon ldquoRelations structure-reactivite grandeurs thermodynamiques de protonationdrsquohrsquoetrsquoerocycles satures et non saturesrdquo Thermochimica Actavol 20 no 3 pp 335ndash345 1977
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
4 ISRN Analytical Chemistry
0
2
4
6
8
10
12
14
0 1 2 3 4 5 6 7 8m
pH
I III
II IV
Figure 2 Potentiometric pH profiles for solutions containing (I)BA 119879BA = 20 times 10
minus3M and Cu(II) and BA in the ratios (II) 1 1(119879Cu = 20 times 10
minus3M and 119879BA = 20 times 10minus3M) (III) 1 2 (119879Cu = 20 times
10minus3M and 119879BA = 40 times 10
minus3M) and (IV) 1 3 (119879Cu = 20 times 10minus3M
and 119879BA = 60 times 10minus3M) respectively 119879 = 250 plusmn 01∘C and 119868 = 01
MKNO3
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
Ni
NiL
NiL3H
NiL2
a(
)
Figure 3 Species distribution curves of the metal ion Ni(II) andthe BA as a function of pH for a solution initially containing 119879Ni =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of themetal set at 100 NiL NiL2 and NiL
3H are
the complexed species with one two and three ligand molecules
In Figure 4 the species CuL3H for the system BA and metal
ion Cu(II) reaches a maximum of 90 at pH 120The secondspecies CuL
2reaches a maximum of 60 at pH 60minus120 and
the CuL complex species in the ratio of 1 moles of ligand toone mole metal presents a maximum of 90 near pH 40ndash100
It can be observed that the stability constants of theNi(II)-BA complexes are lower than Cu(II)-BA complexes
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14pH
CuCuL
CuL3H
CuL2a(
)
Figure 4 Species distribution curves of the metal ion Cu(II) andthe BA as a function of pH for a solution initially containing 119879Cu =20 times 10
minus3Mmetal ion and 119879BA = 60 times 10minus3MBA 119879 = 250 plusmn 01∘C
and 119868 = 01MKNO3 a is the percentage of a species present with
the concentration of the metal set at 100 CuL and CuL2 CuL
3H
are the complexed species with one two and three ligandmolecules
Acknowledgment
The authors thank the Research Fund of Uludag Universityfor the financial support given to the research projects(Project no UAP(F)-201170)
References
[1] F Hueso-Urena N A Illan-Cabeza M N Moreno-CarreteroJ M Martınez-Martos and M J Ramırez-Exposito ldquoSynthesisand spectroscopic studies on the new Schiff base derived fromthe 1 2 condensation of 26-diformyl-4-methylphenol with 5-aminouracil (BDF5AU) and its transition metal complexesinfluence on biologically active peptides-regulating aminopep-tidasesrdquo Journal of Inorganic Biochemistry vol 94 no 4 pp326ndash334 2003
[2] M S Refat S A El-Korashy and A S Ahmed ldquoA convenientmethod for the preparation of barbituric and thiobarbituric acidtransition metal complexesrdquo Spectrochimica Acta A vol 71 no3 pp 1084ndash1094 2008
[3] A Tsunoda M Shibusawa Y Tsunoda N Yasuda K Nakaoand M Kusano ldquoA model for sensitivity determination ofanticancer agents against chemically-induced colon cancer inratsrdquo Anticancer Research vol 14 no 6B pp 2637ndash2642 1994
[4] E S Raper ldquoComplexes of heterocyclic thione donorsrdquo Coordi-nation Chemistry Reviews vol 61 pp 115ndash184 1985
[5] J S Casas E E Castellano M D Couce et al ldquoA gold(I)complex with a vitamin K
3derivative characterization and
antitumoral activityrdquo Journal of Inorganic Biochemistry vol 100no 11 pp 1858ndash1860 2006
[6] M J M Campbell ldquoTransition metal complexes of thiosemi-carbazide and thiosemicarbazonesrdquo Coordination ChemistryReviews vol 15 no 2-3 pp 279ndash319 1975
[7] M C Rodriguez-Arguelles M B Ferrari G G Fava et alldquo26-Diacetylpyridine bis(thiosemicarbazones) zinc complexessynthesis structure and biological activityrdquo Journal of InorganicBiochemistry vol 58 no 3 pp 157ndash175 1995
[8] J S Casas M S Garcıa-Tasende C Maichle-Mossmer et alldquoSynthesis structure and spectroscopic properties of acetato(dimethyl) (pyridine-2-carbaldehydethiosemicarbazonato)-tin(IV) acetic acid solvate [SnMe
2(PyTSC)(OAc)]HOAc
Comparison of its biological activity with that of some struc-
ISRN Analytical Chemistry 5
turally related diorganotin(IV) bis (thiosemicarbazonates)rdquoJournal of Inorganic Biochemistry vol 62 no 1 pp 41ndash55 1996
[9] M B Ferrari G G Fava P Tarasconi R Albertini S Pinelliand R Starcich ldquoSynthesis spectroscopic and structural char-acterization and biological activity of aquachloro(pyridoxalthiosemicarbazone) copper(II) chloriderdquo Journal of InorganicBiochemistry vol 53 no 1 pp 13ndash25 1994
[10] U Koch B Attenni S Malancona et al ldquo2-(2-Thienyl)-56-dihydroxy-4-carboxypyrimidines as inhibitors of the hepatitisC virus NS5B polymerase discovery SAR modeling andmutagenesisrdquo Journal of Medicinal Chemistry vol 49 no 5 pp1693ndash1705 2006
[11] W Beck andN Kottmair ldquoNeue UbergangsmetallkomplexemitNuclein-Basen und Nucleosidenrdquo Chemische Berichte vol 109no 3 pp 970ndash993 1976
[12] N Kottmair and W Beck ldquoTungsten carbonyl complexes of2101584031015840-O-isopropylideneguanosine and 6-mercaptopurinerdquo Inor-ganica Chimica Acta vol 34 pp 137ndash144 1979
[13] A Ashnagar N G Naseri and B Sheeri ldquoNovel synthesis ofbarbituratesrdquo Chinese Journal of Chemistry vol 25 no 3 pp382ndash384 2007
[14] J N Delgado W A Remers and J B Lippincott Eds Wilsonand Gisvoldrsquos Textbook of Organic Medicinal PharmaceuticalChemistry Williams amp Wilkins Philadelphia Pa USA 9thedition 1991
[15] J-L Fillaut I de Los Rios D Masi A Romerosa F Zanobiniand M Peruzzini ldquoSynthesis and structural characterizationof (carbene)ruthenium complexes binding nucleobasesrdquo Euro-pean Journal of Inorganic Chemistry vol 2002 no 4 pp 935ndash942 2002
[16] O Temiz-Arpaci A Ozdemir I Yalcin I Yildiz E Aki-Sener and N Altanlar ldquoSynthesis and antimicrobial activityof some 5-[2-(morpholin-4-yl) acetamido] andor 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substitutedphenyl)benzoxazolesrdquo Archiv der Pharmazie vol 338 no 2-3pp 105ndash111 2005
[17] T W G Solomons and C B Fryhle Organic Chemistry JohnWiley amp Sons Hoboken NJ USA 9th edition 2008
[18] J H Block and J M Beale Wilson and Gisvoldrsquos Textbook ofOrganic Medicinal and Pharmaceutical Chemistry LippincottWilliams ampWilkins Philadelphia Pa USA 11th edition 2004
[19] W O Foye T L Lemke and D A Williams Principles ofMedicinal Chemistry Williams amp Wilkins Philadelphia PaUSA 4th edition 1995
[20] N M Korotchenko and N A Skorik ldquoInteraction of copper(II)and iron(III) with barbituric acidrdquo Russian Journal of InorganicChemistry vol 45 no 12 pp 1945ndash1948 2000
[21] G Schwarzenbach and H Flaschka Complexometric TitrationsInterscience New York NY USA 1969
[22] A E Martell and R J Motekaitis Determination and Use ofStability Constants Wiley-VCH New York NY USA 1989
[23] M-J Blais O Enea and G Berthon ldquoRelations structure-reactivite grandeurs thermodynamiques de protonationdrsquohrsquoetrsquoerocycles satures et non saturesrdquo Thermochimica Actavol 20 no 3 pp 335ndash345 1977
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ISRN Analytical Chemistry 5
turally related diorganotin(IV) bis (thiosemicarbazonates)rdquoJournal of Inorganic Biochemistry vol 62 no 1 pp 41ndash55 1996
[9] M B Ferrari G G Fava P Tarasconi R Albertini S Pinelliand R Starcich ldquoSynthesis spectroscopic and structural char-acterization and biological activity of aquachloro(pyridoxalthiosemicarbazone) copper(II) chloriderdquo Journal of InorganicBiochemistry vol 53 no 1 pp 13ndash25 1994
[10] U Koch B Attenni S Malancona et al ldquo2-(2-Thienyl)-56-dihydroxy-4-carboxypyrimidines as inhibitors of the hepatitisC virus NS5B polymerase discovery SAR modeling andmutagenesisrdquo Journal of Medicinal Chemistry vol 49 no 5 pp1693ndash1705 2006
[11] W Beck andN Kottmair ldquoNeue UbergangsmetallkomplexemitNuclein-Basen und Nucleosidenrdquo Chemische Berichte vol 109no 3 pp 970ndash993 1976
[12] N Kottmair and W Beck ldquoTungsten carbonyl complexes of2101584031015840-O-isopropylideneguanosine and 6-mercaptopurinerdquo Inor-ganica Chimica Acta vol 34 pp 137ndash144 1979
[13] A Ashnagar N G Naseri and B Sheeri ldquoNovel synthesis ofbarbituratesrdquo Chinese Journal of Chemistry vol 25 no 3 pp382ndash384 2007
[14] J N Delgado W A Remers and J B Lippincott Eds Wilsonand Gisvoldrsquos Textbook of Organic Medicinal PharmaceuticalChemistry Williams amp Wilkins Philadelphia Pa USA 9thedition 1991
[15] J-L Fillaut I de Los Rios D Masi A Romerosa F Zanobiniand M Peruzzini ldquoSynthesis and structural characterizationof (carbene)ruthenium complexes binding nucleobasesrdquo Euro-pean Journal of Inorganic Chemistry vol 2002 no 4 pp 935ndash942 2002
[16] O Temiz-Arpaci A Ozdemir I Yalcin I Yildiz E Aki-Sener and N Altanlar ldquoSynthesis and antimicrobial activityof some 5-[2-(morpholin-4-yl) acetamido] andor 5-[2-(4-substituted piperazin-1-yl)acetamido]-2-(p-substitutedphenyl)benzoxazolesrdquo Archiv der Pharmazie vol 338 no 2-3pp 105ndash111 2005
[17] T W G Solomons and C B Fryhle Organic Chemistry JohnWiley amp Sons Hoboken NJ USA 9th edition 2008
[18] J H Block and J M Beale Wilson and Gisvoldrsquos Textbook ofOrganic Medicinal and Pharmaceutical Chemistry LippincottWilliams ampWilkins Philadelphia Pa USA 11th edition 2004
[19] W O Foye T L Lemke and D A Williams Principles ofMedicinal Chemistry Williams amp Wilkins Philadelphia PaUSA 4th edition 1995
[20] N M Korotchenko and N A Skorik ldquoInteraction of copper(II)and iron(III) with barbituric acidrdquo Russian Journal of InorganicChemistry vol 45 no 12 pp 1945ndash1948 2000
[21] G Schwarzenbach and H Flaschka Complexometric TitrationsInterscience New York NY USA 1969
[22] A E Martell and R J Motekaitis Determination and Use ofStability Constants Wiley-VCH New York NY USA 1989
[23] M-J Blais O Enea and G Berthon ldquoRelations structure-reactivite grandeurs thermodynamiques de protonationdrsquohrsquoetrsquoerocycles satures et non saturesrdquo Thermochimica Actavol 20 no 3 pp 335ndash345 1977
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of