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Application of MCD Spectroscopy and TD‐DFT to Nonplanar Core‐Modified Tetrabenzoporphyrins: Effect of Reduced Symmetry on Nonplanar Porphyrinoids
Author(s) -
Mack John,
Bunya Masaru,
Shimizu Yusuke,
Uoyama Hiroki,
Komobuchi Naoki,
Okujima Tetsuo,
Uno Hidemitsu,
Ito Satoshi,
Stillman Martin J.,
Ono Noboru,
Kobayashi Nagao
Publication year - 2008
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.200701611
Subject(s) - chemistry , crystallography , magnetic circular dichroism , spectroscopy , ligand (biochemistry) , circular dichroism , differential pulse voltammetry , annulene , stereochemistry , spectral line , cyclic voltammetry , physics , electrochemistry , biochemistry , receptor , quantum mechanics , astronomy , electrode
The optical spectra of a series of core‐modified tetrabenzoporphyrins were analyzed to determine the effects of core modification, ligand folding, and partial benzo substitution at the ligand periphery on the electronic structure by using magnetic circular dichroism (MCD) and NMR spectroscopy, X‐ray crystallography, cyclic and differential pulse voltammetry, and TD‐DFT calculations. Planar 21‐carba‐, 21‐thia‐, 21,23‐dithia‐, and 21‐oxa‐23‐thiatetrabenzo[ b , g , l , q ]porphyrins reported previously were studied together with the previously unreported 21‐oxa‐ and 21‐carba‐23‐thiatetrabenzo[ b , g , l , q ]porphyrins. The optical properties of these compounds are compared to those of tetrabenzo[ b , g , l , q ]‐, 5,10,15,20‐tetraphenyl‐, 5,10,15,20‐tetraphenyltetrabenzo[ b , g , l , q ]‐21‐thia‐, 5,10,15,20‐tetraphenyltetrabenzodithia‐, 5,10,15,20‐tetraphenyldibenzo[ g , q ]‐21,23‐dithia‐, 5,10,15,20‐tetraphenyldibenzo[ b , l ]‐21,23‐dithia‐, 5,10,15,20‐tetraphenyltribenzo[ g , q , l ]‐21‐thia‐, and 5,10,15,20‐tetraphenylbenzo[ b ]‐21‐thiaporphyrins. Michl's perimeter model and Gouterman's four‐orbital model are used to conceptualize the results and to account for red shifts commonly observed in the spectral bands of nonplanar porphyrinoids.