A highly selective and sensitive chemosensor derived coumarin–thiazole for colorimetric and fluorimetric detection of CN− ion in DMSO and aqueous solution: synthesis, sensing ability, Pd(II)/Pt(II) complexes and theoretical studies

Abstract

A colorimetric and fluorescence turn-on cyanide probe, including coumarin–thiazole and imine (azomethine) group, has been designed and synthesized. It showed an immediate visible color change from yellow to deep red only in DMSO, and an appearance of strong yellow and green fluorescence when CN− was added to DMSO, and a mixture of DMSO:H2O (9:1), respectively. Thus, the sensor can be used to detect CN− in aqueous solution. The sensing mechanism of chemosensor 4 reactions with CN− ion was observed with the deprotonation and addition mechanisms at the same time. The mechanisms of reactions of chemosensor 4 with; CN−, F−, and AcO− were examined using 1H NMR spectroscopy, and were also theoretically supported by DFT and TD-DFT calculations. In addition, the metal complexes of chemosensor 4 with Pd(II) and Pt(II) were also synthesized and all the synthesized compounds were characterized using general spectroscopic methods (FTIR, 1H/13C NMR, and mass spectrometry), magnetic susceptibilities, and conductivity measurements. Also, the molecular structure of 4 was determined using single crystal X-ray analysis.