POSSIBILITY OF MOLECULAR-SWITCH WITH CONTROLLED HYDROGEN BOND: UTILITY OF COMBINATION OF 2,2′-BIIMIDAZOLE AND REDOX-ACTIVE LIGAND

A new inorganic molecule [Co(Hbim)(C₆H₄O₂)(NH₃)₂]₂ that can be used as a new optically durable molecular switch was theoretically designed in the framework of density functional theory. Three stable minima, belonging to ¹A_g, ⁵A₁, and ⁹A_g states, were found in the complex. Theoretically predicted infrared spectra of the complexes showed that a strong peak of NH stretching vibration is observed at 2690, 2120, and 2770 cm^-1 in the ¹A_g, ⁵A₁, and ⁹A_g states, respectively. The apparent red shift of the NH stretching vibration band in the ⁵A₁ state make it possible to distinguish the electronic state from others (¹A_g and ⁹A_g). This means that the complex can be used as a molecular level switch whose memory can be stably read by IR light without any photoreaction process; namely, without memory degradation.