Amino acids binding to Zn 2+ ‐cyclen molecular receptor in aqueous solution

Potentiometric titrations and 1 H 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(HL n )] 2+ and [ZnL(L n )] + 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.