The Use of Graph-theoretical Models to Evaluate Two Electroanalytical Methods for Determination of Stability Constants

Raos, Nenad; Branica, Gina; Miličević, Ante
November 2008
Croatica Chemica Acta;Nov2008, Vol. 81 Issue 3, p511
Academic Journal
Stability constants K1 and β2 of copper(II) complexes with alanine and its five N-alkylated and N,N-dialkylated derivatives were measured by glass electrode potentiometry (GEP) and square wave voltammetry (SWV) and evaluated using graph-theoretical models. Correlations with the connectivity index of the 3rd order, 3χv, show that log K1(GEP) values were better reproduced than log K1(SWV) values; S.E. = 0.18-0.16 vs. 0.29-0.35, respectively. The opposite is true for log β2 (S.E. = 0.51-0.56 vs. 0.39-0.47 for GEP and SWV, respectively). By applying three criteria - 1) difference between GEP and SWV values, 2) difference between SWV and theoretical values, and 3) correlation of experimental error (S.E.exp) to the difference between experimental and theoretical values - it was possible to determine three experimental log K1(SWV) values as problematic. This report demonstrates the value of recently developed graph-theoretical models in planning the experiments and discussing their results.


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