Molar absorption coefficients and stability constants of Zincon metal complexes for determination of metal ions and bioinorganic applications.

Molar absorption coefficients and stability constants of Zincon metal complexes for determination of metal ions and bioinorganic applications. J Inorg Biochem. 2017 Aug 24;176:53-65 Authors: Kocyła A, Pomorski A, Krężel A Abstract Zincon (ZI) is one of the most common chromophoric chelating probes for the determination of Zn(2+) and Cu(2+) ions. It is also known to bind other metal ions. However, literature data on its binding properties and molar absorption coefficients are rather poor, varying among publications or determined only in certain conditions. There are no systematic studies on Zn(2+) and Cu(2+) affinities towards ZI performed under various conditions. However, this widely commercially available and inexpensive agent is frequently the first choice probe for the measurement of metal binding and release as well as determination of affinity constants of other ligands/macromolecules of interest. Here, we establish the spectral properties and the stability of ZI and its complexes with Zn(2+), Cu(2+), Cd(2+), Hg(2+), Co(2+), Ni(2+) and Pb(2+) at multiple pH values from 6 to 9.9. The obtained results show that in water solution the MZI complex is predominant, but in the case of Co(2+) and Ni(2+), M(ZI)2 complexes are also formed. The molar absorption coefficient at 618 nm for ZnZI and 599nm for CuZI complexes at pH7.4 in buffered (I=0.1M) water solutions are 24,200 and 26,100M(-1)cm(-1), respectively. Dissociation constants o...
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research