A highly sensitive and selective bis(salamo)-type fluorescent chemosensor for identification of Cu2+ and the continuous recognition of S2-, Arginine and Lysine.

A novel bis(salamo)-type chemosensor H3L was synthesized and characterized. It was found that the sensor molecule can selectively recognize Cu2+, and its L-Cu2+ is highly sensitive to the detection of S2- anion, Arginine and Lysine when dissolved in ethanol solvent. The sensor H3L can be used to identify a relay sensor for Cu2+, while the L-Cu2+ recognizes S2- anion, Arginine and Lysine with high selectivity and sensitivity over an acceptable physiological pH range. The detection line of the sensor molecule H3L is 1.02 × 10-6 M, and its binding constant to Cu2+ is 1.54 × 106 M-1. The detection line of L-Cu2+ as a sensor is calculated as 5.57 × 10-7 M, and its binding constants with S2- anion, Arginine and Lysine are 2.80 × 105 M-1, 5.32 × 106 M-1 and 5.94 × 106 M-1, respectively. The crystal structure of the Cu(II) complex [Cu4(L)2(CH3OH)2]·2NO3 with the sensor molecule H3L has been determined by single crystal X-ray crystallography.