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Application of the Perimeter Model to the Assignment of the Electronic Absorption Spectra of Gold(III) Hexaphyrins with [4 n +2] and [4 n ] π‐Electron Systems
Author(s) -
Muranaka Atsuya,
Matsushita Osamu,
Yoshida Kengo,
Mori Shigeki,
Suzuki Masaaki,
Furuyama Taniyuki,
Uchiyama Masanobu,
Osuka Atsuhiro,
Kobayashi Nagao
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801742
Subject(s) - magnetic circular dichroism , excited state , chemistry , absorption spectroscopy , atomic orbital , singlet state , absorption (acoustics) , atomic electron transition , spectroscopy , molecular orbital , circular dichroism , spectral line , density functional theory , atomic physics , crystallography , electron , materials science , computational chemistry , molecule , physics , optics , organic chemistry , quantum mechanics , astronomy , composite material
Expanded porphyrins : The electronic excited states of two forms of meso ‐hexakis(pentafluorophenyl)‐substituted gold(III) hexaphyrin(1.1.1.1.1.1), such as that depicted, have been investigated by density functional calculations and magnetic circular dichroism spectroscopy to assign their low‐energy excited singlet states.The electronic excited states of two forms of meso ‐hexakis(pentafluorophenyl)‐substituted gold(III) hexaphyrin(1.1.1.1.1.1) have been investigated by density functional calculations and magnetic circular dichroism (MCD) spectroscopy, in order to assign their low‐energy excited singlet states. We found that the perimeter model can be successfully applied to the interpretation of the electronic states. In the case of the neutral forms ( Au 2 ‐N , Au‐N ), the absorption bands observed in the NIR and visible region can be assigned to π–π* transitions referred to as the L and B bands, respectively, analogous to the Q and Soret bands of regular porphyrins. In marked contrast with the neutral forms, the absorption bands of the reduced forms ( Au 2 ‐R and Au‐R ) are attributed to π–π* transitions involving six frontier molecular π orbitals. By applying the 4 N ‐electron perimeter model, the six orbitals are labeled as h − , h + , s − , s + , l − , and l + , while the observed absorption bands can be assigned to the S, N 1 , N 2 , P 1 , and P 2 transitions, in order of increasing energy.