Naked-eye detection and thermochromic properties of Cu(ii)-3,3′-thiodipropionate complexes with benzimidazole

Abstract

Two new coordination complexes, namely, [Cu(tdp)(H₂O)(bim)₃]·4H₂O (1) and {[Cu(μ₂-tdp)(bim)₂]·4H₂O}_n (2) (tdp = 3,3′-thiodipropionate, bim = benzimidazole), having naked-eye sensor properties and thermochromic behaviors, were synthesized and structurally characterized using elemental analysis, IR and UV spectra, and single-crystal X-ray diffraction, powder X-ray diffraction (PXRD) and thermal analyses (TG, DTA and DTG) techniques. Complex 1 changed color from blue to dark and light green in methanol and DMF solvents, respectively, while complex 2 changed color from light blue to light green only in DMF solvent. Moreover, complex 1 can be used to detect as little as 10 percent methanol in ethanol by the naked eye. The thermochromic properties of the complexes showed that complexes 1 and 2 changed color from blue and light blue to light and dark green at 65 °C, respectively.