Determination of species distribution and formation constants of complexes between ion Cu2+ and amino acids using multivariate regression analysis

In present work, the formation constants, logb110, logb120 and the concentration of [M] and [MLi ] in complex solutions of Cu2+ and the amino acids were determined by using the quantitative electron structure and properties relationships (QESPRs) and quantitative complex and complex relationships (QCCRs). The relative charge nets for complex structures were calculated by using molecular mechanics MM+ and semiempirical quantum chemistry calculations ZINDO/1. The QESPRs and QCCRs models were constructed by the atomic charge net on complex structures and the multivariate regression analysis. These were employed for approximate determination the formation constants logb110, logb120 and the distribution diagram of species [M], [MLi ] in various solutions. These results were compared with those from literature [[3]]. They were also validated by the statistical method ANOVA. The dissimilarities between these models and experimental data are insignificant.
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Determination of species distribution and formation constants of complexes between ion Cu2+ and amino acids using multivariate regression analysisTạp chí Đại học Thủ Dầu Một, số 1 - 2011 DETERMINATION OF SPECIES DISTRIBUTION AND FORMATION CONSTANTS OF COMPLEXES BETWEEN ION Cu2+ AND AMINO ACIDS USING MULTIVARIATE REGRESSION ANALYSIS Le Thi My Duyen(1) – Pham Van Tat (2) (1) University of Dalat – (2) University of Thu Dau Mot ABSTRACT In present work, the formation constants, logb110, logb120 and the concentration of [M] and [MLi]in complex solutions of Cu2+ and the amino acids were determined by using the quantitative electronstructure and properties relationships (QESPRs) and quantitative complex and complex relationships(QCCRs). The relative charge nets for complex structures were calculated by using molecular mechanicsMM+ and semiempirical quantum chemistry calculations ZINDO/1. The QESPRs and QCCRs modelswere constructed by the atomic charge net on complex structures and the multivariate regression analysis.These were employed for approximate determination the formation constants logb110, logb120 and thedistribution diagram of species [M], [MLi] in various solutions. These results were compared with thosefrom literature [[3]]. They were also validated by the statistical method ANOVA. The dissimilaritiesbetween these models and experimental data are insignificant. Keyworks: formation constants, semiempirical quantum chemistry calculations ZINDO/1, multivariate regression analysis, quantitative complex and complex relationships * 1. INTRODUCTION In recent years computer is becoming a helpful tool, an effective means of strong calculation in manydifferent areas. It is used in the inorganic chemistry, analytical chemistry, organic chemistry, physicalchemistry, material simulation and data mining [[1],[2]]. The multivariate analysis methods are becominga convenient and an easy tool for building empirical and theoretical models. The linear correlationrelationships can be assessed from different characteristics of the system. Formation constants of complexes are one of the most important factors to explain reactionmechanisms, chemical properties of biological systems in nature. From the formation constants we cancalculate the equilibrium concentration of components in a solution. These can forecast the changes ofcomplex electronic structure in solution from the initial concentration of the central ion and ligand. Inrecent years the formation constants of the complexes can be determined by experimental ways usingUV-Vis spectral data [[7]] and computational techniques. The theoretical methods used for predictingstability constants of complexes based on the relationship between structural and topological descriptorswere introduced [[8]]. A few topological descriptors of complexes Cu2+ with amino acids were determinedby molecular mechanics methods [[4],[5],[6]]. In this work, the linear relationship between topological parameters and formation constants ofthe complexes is not done. We focused only on constructing the quantitative electron structure and 57Journal of Thu Dau Mot university, No1 - 2011properties relationships (QESPRs) from the atomic charge nets and formation constants of complexesCu2+ with amino acids. These linear models were carried out by using principal component analysis.The atomic charges are calculated using the semiempirical quantum chemical method ZINDO/1 SCFMO. We also reported the quantitative complex and complex relationships (QCCRs) using the atomiccharges. The formation constants logb110 and logb120 of complexes Cu2+ and amino acids were predictedfrom these linear models. Those were also compared to predictive ability of artificial neural networks.The distribution diagram of ions in complex solution was built upon the predicted values of logb110 andlogb120. All the results were also compared with experimental data from literature. 2. METHODS 2.1. Reaction equations In aqueous solution, amino acid dissociates into anion L2- then reacts with metal ion Cu2+: kCu 2+ + lL2− + mH + = [Cu k Ll H m ] (1) Ions Cu2+ participate in reactions with L2- ligands to form complexes [CukLlHm]: [Cu k L l H m ] b klm = (2) [Cu 2+ ]k [L2- ]l [H + ]m 2.2. Data and software The values of logβ110 and logβ120 (with k = 1; l = 1, 2; m = 0) of complexes between Cu2+ ion andthe corresponding amino acids were taken from the literature [[3]], give ...