Two 3D Zn(II)/Co(II)-CPs as fluorescent sensors for turn-on and red-shift sensing of tryptophan and norfloxacin

Abstract

Two three-dimensional (3D) coordination polymers (CPs), namely {[M(seb)(bbimb)]·3H2O}n (M = Zn for 1; Co for 2), were obtained via hydrothermal method using sebacic acid (H2seb) mixed with 1,4-bis(benzoimidazol-1-yl)butane (bbimb). The structures of 1 and 2 both display as 3D frameworks with a 5-fold interpenetrating dia topology. CPs 1 and 2 both exhibit excellent luminescent properties and good water stability. Fluorescence sensing experiments demonstrate that 1 and 2 both can selectively detect tryptophan (Trp) and norfloxacin (Nor) in aqueous solution through turn-on and red-shift effect with remarkable anti-interference ability and low detection limits. The limits of detection (LOD) toward Trp-and Nor are 0.07 μM, 0.08 μM for 1 and 0.41 μM, 0.11 μM for 2. In addition, theoretical calculations and different detection methods were utilized to thoroughly investigate the potential sensing mechanisms for Trp-and Nor. Importantly, 1 and 2 represent two rare examples for sensing both Trp-and Nor via turn-on and red-shift effects. The fluoresence test films of 1 and 2 were prepared which can detect Trp-and Nor quickly with naked eye.