Amino acids binding to Zn2+‐cyclen molecular receptor in aqueous solution

Potentiometric titrations and ¹H NMR spectroscopic studies of amino acids binding to the ZnL]²⁺‐complex where L = cyclen in aqueous solution provide information concerning complexing species identity, their stability, and coordination mode declaration. The amino acids form stable ternary ZnL(HLⁿ)]²⁺ and ZnL(Lⁿ)]⁺ complexes. The observations indicate bidentate coordination mode of the deprotonated amino acids, involving both the amine and the carboxylate functions to the ZnL]²⁺ complex in pH region of about 7.5–9.5. The determined stability constants indicate that ZnL]²⁺ complex is a very efficient receptor for simple amino acids such as glycine and alanine. Copyright © 2010 John Wiley & Sons, Ltd.