Formation Constants and Partial Formation Constants of Some Metal Ions Coordinated with 8 Hydroxyquinoline by Potentiometric Titration

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1 Americn Journl of Chemistry nd Appliction 2015; 2(3): Published online My 10, 2015 ( ISSN: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion Mohmed M. Shht Environmentl ffirs Deprtment, Assiut University Hospitls, Assiut University, Assiut, Egypt Keywords 8-Hydroxyquinoline, Potentiometric, Formtion Constnt, Hevy Metl Ions Received: Mrch 9, 2015 Revised: Mrch 24, 2015 Accepted: Mrch 25, 2015 Emil ddress mohmedshht67@hotmil.com Cittion Mohmed M. Shht. Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion. Americn Journl of Chemistry nd Appliction. Vol. 2, No. 3, 2015, pp Abstrct The ssocition equilibri of HQ nd HQ coordinted with some trnsition metl ctions such s: Al(III), C(II), Cd(II), Co(II), Cu(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) ions were studied using potentiometric technique. The ssocition constnt (K ) of HQ ws clculted from the verge number of protons ttched per repeting unit in the HQ (n A ) t different ph vlues. This vlue of pk which formed ws found to be 6.75.The titrtion curves reveled tht the metl ion replces protons nd coordintes to HQ. In ddition, the use of such titrtion curves could be computed of the formtion constnts (log β) of the different species exist t equilibrium. The formtion constnt (log β) for different molr rtios of species such s 1 : 2, 1 : 1 nd 2 : 1 for metl : 8-quilonol, in solution were computed nd the results were discussed. The vlue of ń nd P L for the metl ions under investigtion were clculted t different ph vlues. The Formtion Constnt (log β) of the coordinted 8-quilonol bsed on HQ Metl ion were computed using ń P L system. Mthemticl clcultions of differentil chnge of ń ( ń) gve shrp signl for clcultions of formtion constnt. From ń there re prtil formtion constnt (log β 2, log β 3, log β 4 nd log β 5 ) which indicte to the protontion degree. The nlyses of potentiometric dt helped us to determine ech vlue of the formtion constnt nd/or prtil formtion constnt for the metl ions such s: Al(III), C(II), Cd(II), Cu(II), Co(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) coordinted with 8- Hydroxyquinoline. 1. Introduction Titrtion with stndrd solution of strong bse is the method of choice for the chrcteriztion of wek cid. Monitoring the titrtion progress by mens of potentiometric mesurements with ph glss electrode llows the ccomplishment of tsks of vrious complexities. From the simple quntittion of single solute to the determintion of the composition of multi-component mixtures together with the cidity constnts of poly functionl cids, computer progrms [1-2] t vrious levels of sophistiction hve been proposed, nd re being continuously developed, in order to llow systems of incresing complexity to be delt with in greement with the principles of sttisticl nlysis of dt. The dissocition constnt is one of the most importnt chrcteristics of

2 38 Mohmed M. Shht: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion phrmceuticl chemicl moiety which hs to be estimted with ccurcy. Poor solubility hs issues not only with formulting the drug; it lso imposes problems in evluting the physicochemicl properties of the molecule itself. Ioniztion constnt (pk) is one mong the prmeter to be estimted with ccurcy, irrespective of solubility constrints. [3]. The pk is the negtive logrithm of the equilibrium constnt (K) of the cid-bse rection of the compound of interest. The importnce of pk in biologic systems needs to preserve reltively constnt environment, including control over the ph of the orgnism s fluids. One wy to chieve this is through the use of "buffers". A buffer is compound which due to its cid-bse chemistry rects to chnges in the environment to preserve ner constnt ph tht is ner the pk of the buffering compound. Potentiometric methods not requiring titrtion with bse, like smple ddition or smple dilution, re seldom used. For instnce, ph mesurements of smple solutions t single known concentrtion of wek cid re sometimes employed to clculte K for clssifiction of the cid strength of series of similr substnces. Mesured volumes of the smple solution, contining single wek cid t concentrtion C, re dded stepwise to known volume V o of wter (the constncy of ionic strength being n importnt prerequisite for obtining esily mngeble dt, n queous solution of n inert electrolyte is preferble). In ordered to obtin either the concentrtion C, or the cidity constnt of the smple cid, K, or both, the experimentl vribles V (the totl volume of smple dded in correspondence of ech step) nd [H ] (the corresponding hydronium ion concentrtion mesured by clibrted glss electrode) cn be processed by computtionl methods ccording to the bsic eqution describing the theoreticl reltion between these quntities [4]. Anlyticl procedures re gretly simplified nd their relibility incresed by the possibility of determining the different nlysis without the need for tedious, complex seprtion which re frequently source of errors. Such n pproch requires new review of well-known nlyticl regents with well-estblished properties nd fetures in order to develop procedures for multi component nlysis. The study of 8 hydroxyquinoline (oxine) which hs been widely used s n nlyticl regent for the determintion of metl ions. It forms insoluble complexes with number of metl ions in queous medi. In other instnces it is necessry previously to remove interference by precipittion or extrction with other regents to chieve the required selectivity [5]. The determintion of different metl ions in the sme smple requires working in sequentil mnner, which results in prolonged times of nlysis. The stepwise protontion equilibri of the lignd were studied (Eqs. 1 to 4) [6], L -1 H H L (1) H L H H 2 L 2 (2) H 2 L 2 H H 3 L 2 (3) H 3 L 2 H H 4 L 2 (4) According to literture [7], K 1 nd K n cn be ssigned to the protontion constnts of the nlyte, while the vlues re somewht different from those of free 8 quinolinol. The difference cn be ttributed to the solvent effect, since, the free 8 quinolinol is insoluble in wter nd its protontion constnts were obtined in the mixture of 1,4 dioxne / wter. The formtion constnts of metl complexes my be expressed either by the overll stbility constnts,β 1, β 2, β 3, β n, or by the stepwise stbility constnts K 1, K 2,..., K n s follows (chrges re omitted): K n = [ML n ] / [ML n-1 ] [L] (5) β n = [ML n ] / [M] [L] n (6) The stepwise stbility constnts re used for the formtion of ML n complexes. For the formtion of protonted, hydroxo, or polynucler complex species, the overll stbility constnts re used [8]: β (M p H q L r ) = [M p H q L r ] / [M] p [H] q [L] r (7) Negtive q-vlues for [HL refer to the formtion of mixed hydroxo complexes or equilibri in which one or more hydrogen ions which do not normlly dissocite re liberted. The binding properties of verge moleculr weight towrds metl ions in dilute queous solutions [9]. It ws possible to estblish the following order for the different metl ions to form incresingly stble complex species Ni(II) < Cd(II) < Cu(II) < Pb(II). The difference in the verge moleculr weight did not seem to hve ny influence on complextion phenomenon. Potentiometric titrtion technique cn be used to determine the hydrogen ion concentrtion in solutions t constnt ionic medium which contins n excess of, for exmple, sodium ions; moreover, complex formtion M n (metl) ion nd coordinted compound (lignd) in the presence of H cn be studied using the glss electrode. The ph vlues of the mixed solvent-wter medi were corrected by the method given by Douheret [10] : ph* = ph δ (8) Where ph* is the corrected reding nd ph is the phmeter reding obtined in solvent wter mixture. The vlues δ or the vrious properties of ech orgnic solvent were determined s recommended previously [9]. The electricl behvior of hydroxyquinoline sulfonic cid nd its complexes with Mn(II), Fe(II), Co(II), Ni(II) or Cu(I1) s well s its slts with Li(I), N(I) or K(I) were studied over the temperture rnge K. All compounds behve like semiconductors. The stbility constnts were clculted t different tempertures in order to determine the thermodynmic prmeters H, G nd S for the complexes studied. [11] A series of complexes of divlent trnsition metl ions

3 Americn Journl of Chemistry nd Appliction 2015; 2(3): with mlonyl bis(slicyloylhydrzone) (H 4 MSH) hve been prepred nd chrcterized with the help of conductometric, potentiometric methods. The proton lignd nd metl lignd stbility constnts were obtined ph-metriclly. The electricl conductivity of solid complexes ws mesured t 289 K. The low molr conductnce vlues observed for these complexes indicte tht, they re non-electrolytes. They re soluble to limited extent in DMF nd DMSO. The elementl nlyses of the complexes indicte tht the complexes hve 1:1 nd 2:1 (M:L) stoichiometry with the existence of wter, chloride, cetone molecules inside the coordintion sphere s evidence from the IR spectrl studies. Further, the complexes hve been formulted by compring C, H, N & metl nlysis dt [12]. The protontion constnts of the lignd nd the stbility constnts of their metl complexes will be evluted potentiometriclly. The complextion rection between some oximes including methyl-2-pyridylketone oxime (MPKO), phenyl-2- pyridylketone oxime (PPKO) nd dicetyl mono oxime (DMO) with some trnsition nd hevy metl ions: Co 2, Ni 2, Zn 2, Pb 2, Fe 2, Fe 3, Cr 3 nd L 3 hs been studied potentiometriclly in queous solution t 25±0.1 C nd ionic strength (µ) of 0.1M supported by KCl. The overll stbility constnts logβ s of respective species were obtined by computer refinement of ph volume dt. The min species in binry systems re ML, ML 2, MLH, MLH 2, ML 2 H, ML 2 H 2, M(OH)L, M(OH) 2 L, M(OH)L 2 nd M(OH) 2 L 2 (LMPKO or PPKO or DMO)[13]. The ssocition equilibri of PHQ nd PHQ coordinted with some trnsition metl ctions such s: Al(III), C(II), Cd(II), Co(II), Cu(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) ions were studied using potentiometric technique. The ssocition constnt (K) of PHQ ws clculted from the verge number of protons ttched per repeting unit in the PHQ mtrix (na) t different ph vlues. This vlue of pk which formed ws found to be 7.75.[14] Kml nd co-workers [15-16], hve prepred spectro nlyticl solutions nd using severl spectroscopic techniques, chrcterized coordintion polymer bsed on poly(8-hydroxyquinoline) complexed to some metl ions. The insertion of Al(III) ction into poly(8-hydroxyquinoline) (PHQ) insted of some metl ions such s Co(II), Ni(II), Zn(II), Fe(III), Cu(II), Mg(II), Cr(III), Mn(II) nd Mo(VI) ions vi ction-exchnge mechnism hs been studied. The stbility constntsfor PHQ coordintion polymers with different metl ions were clculted. The clcultions indicte tht the lrgest stbility constnt nd free energy chnge correspond best to the 2:1 stoichiometry, (2PHQ:1M n ) [17-18]. 2. Experimentl 2.1. Mteril 8 Hydroxyquinoline (8 HQ) ws obtined from Aldrich (chemicl co.,us.). A copper slt Cu (NO 3 ) 2 ws obtined from chemiclly pure of (Merck). All Mterils employed in the present investigtion were of nlyticl regent products from their Anlr grde nitrte slts (BDH) ; Cu(NO 3 ) 2.3H 2 O, Ni(NO 3 ) 2.6H 2 O, Co(NO 3 ) 2, CCl 2, MgCl 2.6H 2 O, NH 4 Fe(SO 4 ) 2.12H 2 O, Al 2 (SO 4 ) 3.16H 2 O, ZnSO 4.7H 2 O, Cd(NO 3 ) 2.4H 2 O, nd Pb(NO 3 ) Instrumenttion The ph mesurements were mde using Jenwy 3305 ph Meter ccurte to ±0.01 ph unit with glss clomel electrode ssembly. The ph meter ws stndrdized ginst ph 4.0 nd ph 10.0 buffers (prepred by dissolving buffer cpsules in definite mount of second deionized wter). Mgnetic stirrer Jenwy1000 ws used for stirring the solutions Preprtion of the Solutions Universl Buffer Solutions A modified universl buffer series derived from tht of Britton [19] ws prepred. The constituents of this series of buffer were prepred s follow:- () A solution of 0.4 M of ech phosphoric nd cetic cids were prepred by ccurte dilution of the A.R. concentrted cids. (b) A solution of 0.4 M boric cid ws obtined by dissolving the pproprite weight of the recrystllized cid in bi distilled wter. (c) A stock cid mixture ws prepred by mixing equl volumes of the three cids in lrge bottle. The totl molrity of the cid mixture ws thus mentioned t 0.4 M. A series of buffer solutions (ph 3 12) were prepred s follow: 150 ml of the cid mixture ws plced in 250 ml mesuring flsk followed by the pproprite volume of 0.4 M NOH solution nd then the flsk ws completed to mrk with bi distilled wter. ph ws mesured with Fisher Scientific Accument Digitl ph meter Preprtion of Solutions for Potentiometric Mesurements Generlly, doubly distilled wter ws used for preprtion of ll solutions employed. NOH solution: Sodium hydroxide (100 m mol L -1 ) crbonte-free NOH solution ws prepred nd stndrdized by titrtion ginst stndrd solution of oxlic cid HNO 3 solution: A stock solution of (100 m mol L -1 ) HNO 3 ws prepred nd its molrity ws checked by titrtion with stndrd KOH solution. Metl slts solutions: Stock solution of 100 m mol L -1 of metls slt studied were prepred nd stndrdized s recommended procedure [20]. NNO 3 solution: A sodium nitrte (0.5 mol L -1 ) stock solution ws lso prepred. The titrtions were crried out t constnt temperture 25 ± 1 o C. The stirring used ws reltively long nd the stirring rte ws reltively low nd fixed for ll experiments.

4 40 Mohmed M. Shht: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion 3. Results nd Discussion 3.1. Determintion of the Stbility Constnt When n incresing volume (V) of solution contining the wek cid HA t concentrtion (C) is dded stepwise to volume (V o ) of solution contining the sme cid t concentrtion C o > 0, the mount (moles) of cid in the solution is given by: C o V o CV (9) Increses proportionlly to the dded volume (V) (note tht the sme is not true for the concentrtion, unless V<< V o ). By expressing this mount in terms of its functionl reltionship to experimentl vrible, V nd [H ], eqution (10) is obtined [21]: Kw F = ( V V )( )(1 ) = C o V o CV (10) K Where [H ] is mesured vrible of hydronium ion concentrtion mesured s ph, pk, is the cidity constnt of the wek cid. This eqution defines n uxiliry vrible F, which is necessrily liner function of V, in nlogy with the "Rigorous Grn function [21] for wek cid titrtion. The cse presently of interest, not previously considered, is multiple ddition of smple contining the wek cid or highly conjugted substnce (such s HQ) t concentrtion C to known volume of wter or of n queous solution of n inert electrolyte. By putting the initil concentrtion of wek cid in the mesured solution, (C o ), equl to zero, the eqution (10) will be reduced to the eqution: Or Kw F = ( V V )( )(1 ) = C V (11) K F = ( V V )(1 ) = CV (15) K Equtions (11) (15) cn be used, in principle, for the determintion of the smple concentrtion C nd they cn be rerrnged to give equtions hving different scope or wider one. For instnce, to clculte hydrolysis of wter (K w ) when C is known eqution (12) cn be written s: H = K ( CV H ) (16) Therefore, eqution (16) yields the cidity constnt (K ) s the grphicl or Lest squres slope of the trnsformed experimentl dt. It cn be observed tht n Eqution equivlent to eqution (16), for instnce, the eqution: K 2 = CV V V (17) This eqution is used when cidity constnt (K ) is clculted from single mesurement of ph. Alterntively, by defining other suitble uxiliry vribles X nd Y tht cn be clculted for ech pir of experimentl dt V nd [H ], it is possible to rerrnge eqution (11) to obtin different Liner eqution of the form: Y = b X (18) Therefore, C nd K cn be obtined by numericl or grphicl liner fit of the vlues of X nd Y, clculted from the experimentl dt s: { 2 ( V V ) K CV ( V V ) = (19) 3.2. Determintion of the pk of 8-Hydroxyquinoline (HQ) } F = H (1 ) = CV (12) K Where K w H = ( V V )( ) (13) With modertely wek cids t moderte dilution K w = [ OH ] is negligible with respect to [H ], Then, the eqution (13) will be reduced to: H = ( V V )[ H ] (14) Therefore, eqution (11) cn, in most instnces, be reduced to the pproximte form s: Fig. 1. Potentiometric titrtion curves of strong lkli (NOH) for different concentrtion of HQ s : ) 0.5, b) 1.0, c) 2.0, nd d) 2.5 m mol L -1, respectively.

5 Americn Journl of Chemistry nd Appliction 2015; 2(3): Different concentrtion of HQ which effect on the volume of bse consumed to give the sme ph vlue in ech concentrtion, re shown in Fig. 1. Thus, from the height of the hlf-ph rising rnge for these curves which corresponding to the ph It cn be clculted tht the pk for ech concentrtion of 0.5, 1.0, 2.0 nd 2.5 mm of HQ gve pk vlues. From these curves, it cn be concluded tht, the vlue of pk is not depend (±0.20) on the concentrtion of HQ Potentiometric Titrtion Studies of PHQ From the potentiometric titrtion curves, the prmeter, (n A ) verge number of protons ssocited with the lignd (the substnce under investigtion, HQ) ws clculted t different ph vlues given by [22]: n A ( V V )( N E ) = Y ( )( ) 1 2 Vo V1 T cl (20) Where Y : is the number of dissocible protons in HQ, V o : is the initil volume, V 1 nd V 2 : re the volume of lkli required to rech the sme ph in the presence ofminerl cid (HNO 3 ) nd (HNO 3 HQ) solutions, respectively. T cl o : is the totl concentrtion of HQ, N o : is the normlity of the stndrd lkli nd, E o, is the initil concentrtion of the free minerl cid (HNO 3 ). The proton HQ formtion curves obtined by plotting n A vs. ph is represented in Fig.2. The vlue of log K 1 H, the first proton ssocition constnt is determined by interplottion t the hlf (n A ) vlues from n A vs. ph grph s seen in Fig.2. The verge vlue of Acidity constnt (pk ) ws found to be The plotting of the differentil of the verge number of protons ssocited with HQ, n A vs. ph give dvntge thn the studies of n A vs. ph. This dvntge tht the n A ph grph hs bnd t certin ph vlue corresponding to the exct vlue of ssocition constnt, s shown in Fig. 3. Fig. 2. Vrition of the verge number of protons ssocited (n A) for HQ vs. ph Fig. 3. Vrition of the first derivtives of n A ( n A) for HQ vs. ph Potentiometric Titrtion Studies of HQ Coordinted with Some Metl IONS Fig. 4. Potentiometric Titrtion Curves of HQ Cu(II) system curves s: ) Free minerl cid (HNO 3), b) HNO 3 HQ (0.1 m mol L -1 ), c) b Cu(II) [1 M n : 2 HQ], d) b Cu(II) [1 M n : 1 PHQ], nd e) b Cu(II) [2 M n : 1 PHQ]. The potentiometric titrtion technique ws lso employed for the determintion of the formtion constnt (log β) of HQ metl complexes consisted of the ph metric titrtion curves of HQ in the bsence nd presence of metl ion (M n ) under investigtion. Thus, the formtion constnt of binry metl ion polymer (M HQ) complex ws determined by the titrtion crried out using different molr rtios of the concentrtion of metl ions nd/or 8- quilonol where, in ech one the totl volume ws kept constnt (50 ml) queous solution. The ionic strength ws mintined constnt by using 0.1 moll -1 of supporting electrolyte (NNO 3 ). Exmintion of the vrious titrtion curves of the different metl ions (M n ) nd HQ (HQ : M n ) systems t different molr rtios (1 : 2, 1 : 1 nd 2 : 1) show tht the higher shift in the volume of lkli dded for metl HQ complex thn

6 42 Mohmed M. Shht: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion the HQ lone. This indictes tht the strong interction between ech of the metl ions with HQ mtrix vi complextion mechnism. The prtition coefficient of ech metl between the two phses is complex function of different equilibrium constnts involved ioniztion of HQ nd formtion of the complex (HQ M n ). The ph rnge (3 10) ws chosen becuse it fcilitted the complex extrction of the regent nd lrge number of metl ions nd/or trnsition metl ions. The titrtion curve of HQ Cu(II) system is shown in Fig.4. Titrtion curves for some metl ions system, HQ - M n, such s: Al(III),C(II), Cd(II), Cu(II), Co(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) ions re studied. Thus, the replcement of hydrogen ion is due to complextion mechnism. From these titrtion curves, it is cler tht the potentiometric titrtion of free minerl cid curves (s curve in Fig.4) re well seprted from 8-Hydroxyquinoline titrtion curves (curves b), which lso seprted from the HQ metl titrtion curves due to the lkli consumed for metl 8quinolinol interction. The different molr rtio curve is curve c which represent HQ - M n with molr rtio (1 M n : 2 HQ), curve d for (1M n : 1 HQ) nd curve e for (2 M n : 1 HQ) Determintion of the Assocition Constnt (pk ) of HQ Coordinted with Some Metl Ions The metl polymer stbility constnt (log β) were estimted from the nlysis of the curves drown between ńnd P L reltionship where ń, is the verge number of lignd (HQ) ttched per metl ion (M n ) nd clculted by this eqution [22] :- ( V3 V2 )( N E ) n = ( V V ) n T o 2 A CM (21) nd P L is the free lignd exponent of t severl ph vlues nd cn be clculted s follows:- 1 β β β j V V PL = T nt V j o 3 CL CM o (22) Where V 1, V 2 nd V 3 re the volumes of lkli required to rech the sme ph in the free minerl cid (HNO 3 ), lignd (HQ) minerl cid nd the minerl cid lignd metl in potentiometric titrtion, respectively. The vlues of ń nd P L for the metl ions under investigtion were clculted t different ph vlues. From the reltion betweenńvs ph s seen in (Fig. 5 ), the hlf of rising portions which corresponding to the ph vlue, give the pk vlue for HQ. This vlue of ph cn determine exctly from First derivtives tretment ofń ( ń), (Fig. 5 b) by the reltion of signl vs ph (The differentil of ńvlues for constnt vlues of ph) the pek give the certin point of ph vlue corresponding to pk. Fig. 5.() Vrition of the verge number of lignd(hq) ttched per metl ion (ń) vs. ph, for HQ-Cu(II) system nd (b) first derivtive of () s ( ń ) vs. ph. The vlues of ń nd P L for the metl ions under investigtion were clculted t different ph vlues. The plots of ń vlues ginst P L were drown for the solution contining molr rtio 1 : 2, 1 : 1 nd 2 : 1(Metl M n : Lignd HQ) rtios for some metl ions such s: Al(III), C(II), Cd(II), Cu(II), Co(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) ions. The vlues of ńnd P L for the metl ions under investigtion were clculted t different ph vlues Determintion of the Formtion Constnts (log β) of HQ Coordinted with Some Metl Ions Bsed on ( ń) vs. P L System A plotting of ń ginst P L ( P L = 0.5), this plotting is dvntges thnńvs. P L since tht gives us mxim t the vlue of the formtion constnt (log β) nd lso described the

7 Americn Journl of Chemistry nd Appliction 2015; 2(3): number of species could be formed from Lignd metl interction by the number of mxim could be formed. The curves of ń vs P L for M n HQ with the molr rtio ( 1 : 2, 1 : 1 nd 2 : 1) were studied. The nlysis of potentiometric dt presented tht, in ll the investigted systems re formed ccording to the protontion degree then give formtion constnt (log β) nd prtil formtion constnt (log β p q ) refers to the rection [23] s: M L H = M LH (23) j z ( j p z) p q p q The results presented tht, some metls (for the molr rtio 1 metl : 2 lignd) give two species such s: C(II), Zn(II), Ni(II) nd Fe(III) then hve two vlue of the prtil formtion constnts (log β 1 nd log β 2 ), for exmple s shown in (Fig. 6 nd b). Fig. 7. ). ń vs PL of HQ-Al(III) system, (2:1 ) Fig. 6. ). ń vs P L of HQ - Fe(III) system, ( 2 : 1 ) Fig. 7. b). ń vs P L of HQ-Al(III) system, (2:1) Both Cu(II) nd Pb(II) give four species then hve four vlues of prtil formtion constnt (logβ 1, log β 2, log β 3 nd log β 4 ) respectively, for exmple s shown in (Fig. 8 nd b). Fig. 6. b). ń vs P L of HQ-Fe(III) system,( 2 : 1 ) Other metl ions give three species such s: Al(III), Co(II) nd Mg(II) ions. These species indicte tht there re three prtil formtion constnt log β 1,log β 2 nd log β 2, for exmple s shown in (Fig. 7 nd b). Fig. 8. ). ń vs P L of HQ-Pb(II) system,(2:1 )

8 44 Mohmed M. Shht: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion Fig. 8. b). ń vs P L of HQ-Pb(II) system,( 2 : 1 ) While, Cd(II) give five species then hve five vlues of prtil formtion constnt (logβ 1, logβ 2, log β 3, log β 4 nd log β 5 ) respectively, for exmple s shown in (Fig. 9 nd b). Fig. 9. b). ń vs P L of HQ-Cd(II) system,(2:1) Also, The curves of ń vs P L for M n HQ with the molr rtio ( 1 : 1 nd 2 : 1) were studied ndthe ll vlues of the formtion nd prtil formtion constnts for HQ M n were listed in Tble 1 Fig. 9. ). ń vs P L of HQ-Cd(II) system,( 2 : 1 ) Tble 1. Formtion constnts (log β) nd prtil formtion constnts (log β p q) vlues for metls coordinted with HQ t different rtios of Metl : lignd. No M Ions Rtio M : HQ M-HQ β 1 β 2 β 3 β 4 β 5 1 C(II) 1 : : : Zn(II) 1 : : : Fe(III) 1 : : : Ni(II) 1 : : : Al(III) 1 : : : Co(II) 1 :

9 Americn Journl of Chemistry nd Appliction 2015; 2(3): M Ions Rtio M : HQ M-HQ No β 1 β 2 β 3 β 4 β 5 1 : : Mg(II) 1 : : : Cu(II) 1 : : : Pb(II) 1 : : : Cd(II) 1 : : : Conclusion In the present pper protontion constnts nd complex formtion equilibri between 8-Hydroxyquinoline with some trnsition nd hevy metl ions including Al(III), C(II), Cd(II), Cu(II), Co(II), Fe(III), Mg(II), Ni(II), Pb(II) nd Zn(II) ions hve been studied in queous solution t 25.0±0.1 C, using glss electrode potentiometriclly. The protontion constnts of the lignds nd formtion constnts of the resulting complexes were computed from titrtion dt. The overll protontion constnts of lignds nd the stbility of their metl complexes were clculted from computer refinement of the ph volume dt. The results presented tht, some metls such s: C(II), Zn(II), Ni(II) nd Fe(III) (for the molr rtio 1 metl : 2 lignd) hve two vlues of the formtion constnts log β 1 nd log β 2. Other metl ions such s: Al(III), Co(II), nd Mg(II) ions give three prtil formtion constnts (log β 1, log β 2 nd log β 3. Both Cu(II) nd Pb(II) hve four vlues of prtil formtion constnts log β 1, log β 2, log β 3 nd log β 4. While, Cd(II) hve five vlues of prtil formtion constnts (logβ 1, logβ 2, log β 3, log β 4 nd log β 5 ). References [1] Legget, D. J. (1985). Computtionl methods for the determintion of formtion constnts, Plenum Press, New York,. [2] Mrtell, A. E. nd Motekitis, R. J.( 1988). VCH, New York. [3] Rvichndirn, V., Devrjn, V., Msilmni, K.(2011). Determintion of ioniztion constnt (pk) for poorly soluble drugs by using surfctnts: novel pproch. Der Phrmci Lettre, 3 (4) [4] Mcc, C. (1990). Linerized multiple stndrd dditions for the potentiometric determintion of wek cids. Tlnt, 37, [5] Blnco, M., Coello, J., Gonzlez, F., Iturrig, H. nd Mspoch, S.(1989). Simultneous determintion of metl ions: Spectrophotometric determintion of binry, ternry nd quternry mixtures of luminium, iron, copper, titnium nd nickel by extrction with 8-hydroxyquinoline. Anl. Chim. Act, 226, [6] Xun-Cheng Su, Zhi-Fen Zhou nd Hu-Kun Lin.(2001). Novel 8-hydroxyquinoline substituted open chin dioxotetrmine nd its metl complexes: Synthesis nd property studies in queous solution. Indin Journl of Chemistry, 40 A, [7] Stevenson, R. L. nd Freiser, H.(1976). Tridentte lignds derived from substitution in the methyl group of 8- hydroxyquinldine. Anl. Chem., 39(12), [8] Lurih. J. Ljunen, Roberto Portnov, Juh Piispnen nd Mrlen Tolzzi.(1997).Hydroxycrboxylic cid complexes with protons nd metl ions nd the ccompnying enthlpy chnges- Prt I: Aromtic ortho-hydroxycrboxylic cid. Pure &Appl. Chem., Vol. 69, No. 2, [9] Ctherine Morly, Monique Cromer, Yolnde Mouginot nd Olivier Vittori. (1999). Potentiometric study of Cd(II) nd Pb(II) complextion with two high moleculr weight poly(crylic cids); comprison with Cu(II) nd Ni(II). Tlnt, 48, [10] Douheret, G. (1975). Medium effects in queous orgnic solvents. Influence of solute on trnsfer prmeters. Journl of Electronlyticl Chemistry nd Interfcil Electrochemistry, 61(2), [11] Abd El Whed, M.G., El Mnkhly, K.A., El Kososy, N. (1995). Physicochemicl studies of hydroxyquinoline sulfonic cid nd its trnsition metl complexes. Mterils Chemistry nd Physics 41, [12] Askr, E.I., Shokry, H., Al. Hshmy, D.,(2010). Potentiometric nd conductometric studies of mlonyl bis(slicyloylhydrzone) nd divlent metl complexes. Journl of Sudi Chemicl Society, 14, [13] Hmid Rez Rjbi, Mrzieyeh Sdt. Nibnd. (2008). Potentiometric study of binry complexes of methyl 2-pyridyl ketone oxime, phenyl 2-pyridyl ketone oxime nd dicetyl monooxime with some trnsition nd hevy metl ions in queous solution. Spectro chimic Act Prt A 71, [14] Mohmed M. Shht, Determintion of the Formtion Constnts of Some Metl Ions Coordinted with poly (8 Hydroxyquinoline). Interntionl Journl of Advnced Reserch (2014), Volume 2, Issue 6,

10 46 Mohmed M. Shht: Formtion Constnts nd Prtil Formtion Constnts of Some Metl Ions Coordinted with 8 Hydroxyquinoline by Potentiometric Titrtion [15] Mostf M. Kml, Seddique M. Ahmed, Mohmed M. Shht nd Yssien M. Temerk. (2002). Differentil Pulse Polrogrphic (DPP) of Poly (8 Hydroxyquinoline) Mtrix. Anl. nd Bionl. Chem., 372, [16] Ahmed, Seddique M., Shht, Mohmed M., Kml, Mostf M.(2003). Spectrophotometric Studies of the Coordintion polymers Bsed on Poly(8-Hydroxyquinoline) Mtrix. J. Inorg. Orgnomet. Polym. 13, [17] Kml, Mostf M., El- Syed, Abd El-Aziz Y., Ahmed, Seddique M., Omrn, Ahmed I., Shht, Mohmed M.(2009). Ction exchnge mobility on Poly(8-hydroxyquinoline) mtrix. J. Inorg. Orgnomet. Polym. 19, [18] Mohmmed. M. Shht, Seddique. M. Ahmed nd Mostf M. Kml. (2013). Cthodic Stripping Differentil Pulse Voltmmetric Determintion of Poly(8 Hydroxyquinoline) Mtrix. IJPAC-Interntionl Journl of Pure nd Applied Chemistry, 8 (3), [19] Britton, H.T.S. (1952). Hydrogen Ions Fourth Edition. [20] Vogel A. I. (1989). Text book of quntittive inorgnic nlysis, 5th edn. EIBS Longmn. London, p [21] Crlo Mcc nd Merkoci. (1994). Potentiometric chrcteriztion of wek cids by multiple smple ddition I. Liner equtions nd intrinsic performnce of the method. Tlnt, 41, (12), [22] Irving, H. nd Rossotti, H. S. (1954). The clcultion of formtion curves of metl complexes from ph titrtion curves in mixed solvents. J. Chem. Soc., [23] Alessndro De Roberties, Concett De Stefno, Antonio Ginguzz nd Silvio Smmrtno. (1999). Binding of polynions by biogenic mines III Formtion nd stbility of protonted spermidine nd spermine complexes with crboxylic lignds. Tlnt, 48,