Coumarin-based multifunctional chemosensor for arginine/lysine and Cu2+/Al3+ ions and its Cu2+ complex as colorimetric and fluorescent sensor for biothiols

A new chemosensor L1 based on coumarin was synthesized straightforward. It serves as a colorimetric and fluorescent probe for selective and sensitive detection of Arg and Lys over other common amino acids Cys, Hcy, GSH, Phe, His, Met, Gly, Val, Tyr, Glu and Leu. Among various metal ions L1 is able to detect Cu2+ ion by the naked eye with high selectivity and sensitivity. The probe L1 can be utilized for fluorescent sensing of Cu2+ and Al3+ ion with the detection limit of 8 mu M and 2 mu M, respectively. The 'in situ' formed L1-Cu2+ ensemble may be used for colorimetric and fluorescent recognition of Cys, Hcy and GSH over other common amino acids including Phe, His, Met, Gly, Val, Tyr, Glu, Arg, Lys and Leu. The detection limit of the ensemble L1-Cu2+ toward Cys, Hcy and GSH reached 10 mu M, 10 mu M and 16 mu M, respectively. Possible sensing mechanism of L1 toward Arg/Lys and Cu2+/Al3+ ions and the ensemble L1-Cu2+ toward the biothiols is proposed.