binding energy of Zn2+ ligands



 Dear CCL'ers,
 
I am looking for literature describing the influence of the basicity of metal ion ligands (ideally Zn2+ ligands) on the binding energy.
 
For example, I would expect the binding energy for an imidazole to be more favorable than for an imidazole with an electron withdrawing substituent, let's say an -SO2-group.
 Can somebody point me to articles on this matter?
 Thanks a lot in advance,
 Oliver
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 Oliver Hucke, Dr.
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