Novel molecular switches based on viologen ligand and its transition metal complexes

In this work, the viologen derivative was prepared by reacted of bis (3-chloroacetylacetone) ethylenediimine (AN-Cl) with mono-methylviologen (C1V+). The switching motion between dicationic viologen compound C1V2+AN-Cl.2PF6^- and diamagnetic intermolecular π-dimer (C1V+AN-Cl. PF6^-)2 was triggered through the reduction by 1 electron/viologen unit. This molecular switch was followed by UV-Visible absorption spectrometry. The viologen compound C1V2+AN-Cl.2PF6- was titrated with Zn2+, Cu2+, Co2+, and Fe2+ ions to afford metal complexes in the solution of M2+-C1V2+AN-Cl.2PF6-. Moreover, four molecular switches were attained from those metal complexes (M2+-C1V+AN-Cl. PF6^-)2 by the chemical reduction stimuli including the characterization of complexes of M2+-C1V12+AN-Cl.2PF6^- were performed by UV-Visible absorption spectroscopy. It was noticed that ratio of metal to the ligand in the complexes of Zn2+, Cu2+, Co2+, and Fe2+ was 1:1. Switching properties of the novel viologen derivatives with intermolecular dimer were studied by the reduction with activated zinc powder and followed by the absorption spectroscopy. After the 1e- reduction viologen unit in C1V12+AN-Cl.2PF6^- and M^2+-C1V1^2+AN-Cl.2PF6^-, intermolecular dimerized viologen radicals occurred.