Theoretical Study of Geometries and Electronic Transition of Color-Switching Molecules:Tetra-Aza Macrocycle and Its Zinc Complexes

摘要

Tetra-aza macrocycles containing 2,2'-bipyridine moieties fascinatingly undergo color-switching.Here,a tetra-aza macrocycle was analyzed as well as its zinc complexes from the viewpoint of ab initio molecular orbital(MO)and density functional theory(DFT)calculations.As a result of systematic geometry searches,obtained geometries of stable conformers were consistent with the structural formula developed from the experimental results.Transition energies and oscillator strengths of the stable conformers were calculated based on time-dependent DFT(TDDFT)and compared with the experimental data.The effect of the solvent was considered by using a polarization continuum model(PCM).The calculated transition energies qualitatively agreed with the experimental UV spectra.Structural changes upon com-plexation and the features of the molecular orbitals related to the transition from the ground state to the excited states are discussed.