title: Theoretical study of electronic structure and absorption spectra of diacid and zinc species of series of meso-phenylporphyrins.
abstract: DFT and TDDFT calculations with density functionals (PBE1PBE, B3LYP, and PBEPBE) have been employed in a study of HCl-acidified diacids of a series of meso-phenylporphyrins. This study aims to clarify the influence of conformational distortion, meso-phenyl substituents, and counterion Cl- on absorption spectra of porphyrin derivatives. Calculations indicate that all three factors increase the MO's level and decrease the Gouterman HOMO-LUMO gap; this, further, brings about the redshift of absorption band. In comparison with experimental methods, the PBE1PBE method produces a more credible description of UV-vis spectra than other two methods. TDDFT calculation with the PBE1PBE method indicates that the electronic effect of the meso-phenyl group is dominant for the spectral redshift of porphyrin diacid series as observed in zinc porphyrins. The redshift of the B band of porphyrin diacids is primarily caused by an electron-donating effect of the meso-phenyl group, whereas the Q band is more sensitive to the π electron delocalization effect. The counterion is indispensable in a theoretical study of electronic and spectral structure of porphyrin diacids.
authors.affiliation: Department of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, China. zhangyhi@nankai.edu.cn
authors.forename: Ying-Hui
authors.initials: YH
authors.lastname: Zhang
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: Zhao
authors.forename: Wen-Juan
authors.initials: WJ
authors.lastname: Ruan
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000143:Acids / Q000737:chemistry*; D004581:Electronics; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D015032:Zinc / Q000737:chemistry*
chemical_list: D000143:Acids; D011166:Porphyrins; C508866:meso-tetraphenylporphyrin diacid; D015032:Zinc