title: Theoretical study of photo-physical properties of indolylmaleimide derivatives.
abstract: Photo-physical properties of bromo-indolylmaleimide (IM-Br), indole-succinimide (IS), and their anions were theoretically investigated compared with the previous theoretical result for indolylmaleimide (IM) [Phys. Chem. Chem. Phys., 2010, 12, 9783]. The energies for the electronic excited states as well as the ground states were computed for these molecules using the multi-reference perturbation calculations based on the second order Rayleigh-Schrödinger perturbation theory (CASPT2) at the cc-pVDZ basis set level. The electron-accepting or electron-donating effect caused by bromine-substitution was discussed in the intra-molecular charge transfer (ICT) mechanism. The order of natural orbitals of the bromine-substituted monovalent anion with a deprotonated indole NH group (I((-))M-Br) was found to be rearranged by the effect of electron-donation, which leads to pseudo-crossing of the potential energy cures of the S(1) and S(2) states. The large stokes shift observed for I((-))M-Br was due to pseudo-crossing. Meanwhile, IM and IM-Br show abnormal deprotonation, which is explained by the charge distribution on the indole and maleimide moieties. Finally, the monovalent anions I((-))M-Br and I((-))M by a deprotonation of the indole NH end and the neutral IS were proposed to be the most feasible candidates corresponding to the experimental spectra in solution.
authors.affiliation: Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China.
authors.forename: ZiLong
authors.initials: Z
authors.lastname: Zheng
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakazono
authors.forename: Shinkoh
authors.initials: S
authors.lastname: Nanbu
mesh_terms: D004579:Electron Transport; D007211:Indoles / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011522:Protons; D011789:Quantum Theory; D013057:Spectrum Analysis
chemical_list: D007211:Indoles; D008301:Maleimides; D011522:Protons; C043592:maleimide