Chemical speciation of binary complexes of embelin with some biologically important metal ions.

Protonation and complexation equilibria of embelin were investigated in 86% v/v dimethyl sulphoxide - water mixture electrometrically at an ionic strength of 0.17 mol dm-3 and at a temperature of 303K. The best fit chemical models were arrived at based on statistical grounds employing crystallographic R factor, χ2, skewness and kurtosis. The existence of binary complex species with Co(II), Ni(II), Cu(II) and Zn(II) were established from modeling studies using the computer program MINIQUAD75. Distribution diagrams of various species of the complex in relation to pH are presented.