Molecular probe for selective detection of thiols in water of neutral pH

The ternary complex, Zn(cyclen)(lumazine)](+) that can be readily obtained by mixing cyclen, zinc perchlorate, and lumazine in water in a 1:1:1 molar ratio serves as a molecular probe that detects selectively thiols in an aqueous solution of neutral pH. Thiols successfully displace the lumazine in the molecular probe, which is accompanied by a decrease of the fluorescence. The molecular probe is useful for identification of cysteine among essential amino acids and detection of glutathione in aqueous solution of neutral pH.