Structural and chromotropism properties of copper(II) complexes containing a tridentate ligand

Two dinuclear complexes of [LCu(Cl)(μ-Cl)CuCl 3 ][LCu(Cl)(μ-Cl)CuL(H 2 O)]Cl, 1 and [LCu(Br)(μ-Br)] 2 Br, 2 , with a tridentate ligand of 3-((pyridin-2-ylmethyl)amino)propanamide, L, were prepared and characterized by physicochemical (elemental analyses, molar conductance measurements, thermogravimetry) and spectroscopic (IR, UV–vis) data. The crystal structures of compounds have been identified by single-crystal X-ray diffraction analyses and showed that the tridentate ligand L functions as an N 2 O-donor via the nitrogen atoms of the secondary amine and pyridyl moieties together with the oxygen atom of the amide group. The structural geometry about the copper(II) ions is a distorted square pyramid. The compounds are chromotropic and their reversible chromotropism was investigated by utilizing spectral analysis. The halochromism was due to structural change and followed by ionization of the coordinated water molecules and deprotonation of the secondary amine moiety. It was discovered that the solvatochromism of the compounds arisen from the structural change followed by the solvation of the vacant sites of the complexes. The compounds demonstrated ionochromism and sensitivity and selectivity towards CN − and N 3 − anions in the presence of other pseudo-halide anions. Graphic abstract