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Abstract
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Two dinuclear doubly bridged copper(II) complexes [LCu(μ-Cl)Cl]2 (1) and [LCu(μ-Br)Br]2 (2), where L represents N-benzyl(pyridine-2-yl)methaneamine, have been synthesized to investigate their chromotropic behavior. The structures of the complexes were characterized by elemental analyses, various spectroscopic techniques (IR, UV–Vis, and EPR), molar conductance measurements and thermal analysis. The crystal structure of compound 1 indicated both copper(II) centers are located in N2Cl3 environments with distorted square pyramidal geometries, which sharing one base to apex edge. The complexes are chromotropic and their solvatochromism, halochromism, and thermochromism properties were investigated by visible absorption spectroscopy. The solvatochromic properties of the complexes are attributed to structural changes in various solvents. Their halochromism phenomena arise from protonation and deprotonation of coordinated ligands in the pH range of 2.0-10.5, and the reversible thermochromism in DMF and DMSO solutions is triggered by replacing the ligands by solvent molecules.
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