Ultra Chemistry Vol. 8(2), 239-242 (2012). Influence of ionic strength of medium on the thermodynamic parameters of substituted heterocyclic drug with Ce (III), Gd (III) complexes
J.P. NEHETE1, G.P. WAGHULADE3 and A.N. SONAR2
(Acceptance Date 20th July, 2012) Abstract
The metal-ligand and proton–ligand stability constant of Ce(III)
and Gd(III) with substituted heterocyclic drug (Montelukast) were
determined at various ionic strength by pH metric titration. NaClO4 wasused to maintain ionic strength of solution. The results obtained were,extrapolated to the zero ionic strength using an equation with oneindividual parameter. The thermodynamic stability constant of thecomplexes were also calculated. Key word: Stability constant, ionic strength, substituted
constant of vanadium with glycene at variousionic strength by potentiometric titration
The substituted heterocyclic drug is
technique. Majlesi7 et.al. have determined the
used for the treatment of asthma. It has seasonal
stability constant of Mo (IV) with Iminodiacetic
anti- allergies properties.1-2 It forms complex
acid at different ionic strength maintain by
with Ce(III) and Gd(III). Th. Saroda Devi3
using sodium per chlorate. Sharma8 et.al. have
et.al. have studied the stability constant of Co
studied the effect of ionic strength and solvent
(III) with 1-Amidino-0-methylurea as primary
ligand at different ionic strength. Agrawal4
have also studied the mechanism of protonation
et.al. have studied the influence of ionic
and complex formation of binary complexes
strength of medium on complex equilibria.
of La (III), Ce (III), Pr (III) and Nd(III) with
Meshram5 et.al. have studied the association
and dissociation constant of Pr(III) complexes
with 3-(2-hydroxy-3-Iodo-5-methyl phenyl)1,5
detail study of complex under identical set of
diphenyl pyrazoline at different ionic strength.
experimental condition is still lacking. It was
Khorrami6 et.al. have studied the stability
thought of interest to study the effect of ionic
dependence of proton-ligand stability constant
complexes of substituted heterocyclic drug
and metal-ligand stability constant on ionic
with Ce (III) and Gd(III) in 70% ethanol-water
strength of medium was examined by taking
fix concentration of metal nitrates and ligandsolution during pH metric titration. The system
has been studied at 0.02, 0.04, 0.06, 0.08, 0.1Mionic strength by varying the concentration of
sodium per chlorate. The total ionic strength
of medium is calculated by equation.
(accuracy ± 0.01 units) using combine glasselectrode at 208 K. Pure rare earth nitrates
µ = ½ C Z 2
(99.9% Pure) were used. All metal nitrates
Ci, Zi are the concentration and valency of ith
U.S.A. Metal nitrate was prepared in triplydistill water and concentration was estimated
by standard method. The solution of drugs was
ligand constant of Ce(III) and Gd(III) complexes
prepared in solvent. The pH metric reading in
at different ionic strength 0.02,0.04,0.06, 0.08
70% ethanol –water mixture were converted
and 0.1M determined. These values determined
by using Irving-Rossotties method. From table
proposed by Van Uitert Haas. The ethanol was
1, it was seen that the values of proton–ligand
purified by the method described by Vogel9.
stability constant (PK) decreases with increasing
The overall ionic strength of solution was
ionic strength of medium. The metal-ligand
constant maintains by adding NaClO4. All the
stability constant (logK) also decrease with
solutions were titrated with standard carbonate
increasing ionic strength. For determination of
free NaOH (0.2N) solution at different ionic
stability constant at zero ionic strength the
strength. The titration was carried out at ionic
strength by adding NaClO4 (0.02, 0.04, 0.06,0.08, 0.1M).
logK = logK0 + A
pK = pK0 – A
metric titrations of solutions of –1) Free HClO4 (A)
Where K0 is the formation constant at zero
ionic strength, pK0 is proton-ligand stability
constant at zero ionic strength, ‘A’ is the Debye-
Data obtained from each titration is plotted as
2 is the difference in
pH Vs volume of NaOH added and corresponding
square of the changes of product and reactant
The pK0 and logK0 values were Result and Discussion
calculated by plotting the graph of pK, logK ,
Influence of ionic strength of medium---Ce (III), Gd (III) complexes.
Table 1. Proton–ligand (pK) and metal-ligand stability constant (LogK)
values for Ce (III) and Gd (III) with Montelukast at various ionic strength (µ)
Montelukast Ce(III) 0.02 Montelukast Gd(III) 0.02
Table 2. Thermodynamic stability constant (pK0and Log K0)
values for Ce (III) and Gd (III) with Montelukast. Montelukast Ce(III) Montelukast Gd(III)
LogK1 Vs 1 Vs
Table 3. Values of Z2 determined from the plots of PK Vs µ
HL H+ + L-
L- + M+3 ML+2
ML+2 + L- ML +1
HL H+ + L-
L- + M+3 ML+2
ML+2 + L- ML +1
Ultra Chemistry Vol.8(2), (2012).
Dr. R.P. Falak, D.D.N. Bhole College Bhusawal
obtained from different plots. The plots pK, References 1, logK2 versus
the entire range of ionic strength for both
1. Lipkowitz, Myron A. and Navarra, Tova,
systems. It shows that the bronsted relationship
The Encyclopedia of Allergies (2nd ed.)
is valid for dissociation equilibrium. Fazlur
Facts on File, New York, p. 178 (2001).
Rahman10et. al. have determined similar
results of stability constant of different metal
3. Th. Saroda devi and AK. Manihar Singh,
oxime at 0.1,0.05, and 0.01M ionic strength in
J. Ind. Coun. Chem, Vol. 24 No. 2, 32-35
4. P.B. Agrawal and M.L. Narwade, Acta
The values of Z2 were calculated Ciencia Indica, XXIXC(2), 141(2003).
from the slope of plots PK Vs
, LogK1 Vs
5. Y.K. Mehram, A.U. Mandakmare and M.L.
Narwade, Orien. J. of Chem., Vol. 16(1),
equal to 0.5161.11 The value of Z2 given in
table 3. The observed value of Z2 is different
6. S.A. Khorrami, H. Bayat, S. Sharifi and
than the expected value. These values do not give
M. Shafai, J. Chem. Eng. data, Vol. 41(6),
conclusive evidence regarding the magnitude
of the charge of reacting species. This discre-
7. K. Majlesi, F. Gharib and M. Arafati, J.
pancy may be due to the limited applicability
Inorg. Chem., Vol. 51 No. 2, 1982-1986
of Bronsted equation.Narwade12, Sathe and
meshram4 also recorded same discrepancy.
8. S. Sharma, M. C. Shah, D. Dalwadi, F.
Thakur and J.J. Vora, Research J. ofConclusion Chem. and Envi., Vol.12(4), 29-34 (2008).
9. G. H. Vogel’s, Jaeffery, S. Bassetl, R. C.
The calculated values of stability constant
Denney “Text book of quantetative chemical
at various ionic strength are high. From data
analysis”. Vth Ed., ELBS Longman, 53
the conclusion is, the complexes of Montelukast
with Ce (III) and Gd (III) is quite stable at
10. F. Rahman, S.N. Rastogi and U.K. Jettey,
over all range of ionic strength. The values of
J. Ind. Chem. Soc., 67, 342 (1990).
11. R.A. Robinson and R.H. Stroke, “Electrolyte
from all plots was good agreement of results.
Solutions” IInd Ed. Butterworths, 468(1959). Acknowledgement
12. M.L. Narwade, S.W. Sathe, Acta cienciaIndica, VII C (1), 10 (1982).
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