Journal of the Chemical Society, Dalton Transactions p. 3429 - 3436 (1996)
Update date:2022-08-03
Topics:
Hariprasad, Gali
Dahal, Sanjay
Maiya, Bhaskar G.
The free-base, copper(II) and zinc(II) derivatives of 5,10,15,20-tetraarylporphyrin (aryl = phenyl, 4-methyl-phenyl or 4-chlorophenyl) and the corresponding brominated 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraarylporphyrin derivatives have been synthesized and their spectral and redox properties compared by UV/VIS, 1H NMR, ESR and cyclic voltammetric methods. Substitution with the electron-withdrawing bromine groups at the pyrrole carbons has a profound influence on the UV/VIS and 1H NMR spectral features and also on the redox potentials of these systems. On the other hand, electron-withdrawing chloro or electron-donating methyl groups at the para positions of the four phenyl rings have only a marginal effect on the spectra and redox potentials of both the brominated and the non-brominated derivatives. The ESR data for the copper(II) derivatives of all these systems reveal that substitution at either the β-pyrrole carbons and/or the para positions of the meso-phenyl groups does not significantly affect the spin-Hamiltonian parameters that describe the metal centre in each case. Collectively, these observations suggest that the highest-occupied (HOMO) and lowest-unoccupied molecular orbitals (LUMO) of the octabromoporphyrins involve the porphyrin π-ring system as is the case with the non-brominated derivatives. Investigations have been carried out to probe the electronic structures of these systems by three different approaches involving spectral and redox potential data as well as AM1 calculations. The results obtained suggest that the electron-withdrawing β-bromine substituents stabilize the LUMOs and, to a lesser degree, the HOMOs and that the extent of these changes can be fine-tuned, in a subtle way, by substituting at the meso-aryl rings of a given porphyrin.
website:http://www.shtopchem.com/
Contact:0086-0576-87776998
Address:room no 1608,xuhui business building yude road,xujiahui street, xuhui district
Frapp's Chemical (NFTZ) Co.,Ltd
Contact:+86-576-86137892
Address:General Chamber of Commercial Building, 159 Wanchang Middle Road, Wenling, Zhejiang, China
Anhui Sholon New Material Technology Co., Ltd.
website:http://www.sholonchem.com
Contact:+86-550-5261666
Address:4/F Block B, Beijing Chemical Building.No.520 Tianrun Road ,Science & Education Town Wujin District, Changzhou City Jiangsu Province
Contact:+86-571-86491666
Address:SHI XIANG ROAD
Taizhou Crene Biotechnology co.ltd
Contact:86-576-88813233 88205808
Address:Economic Developed Zone of Taizhou Zhejiang China
Doi:10.1246/cl.1997.917
(1997)Doi:10.1016/0960-894X(96)00392-7
(1996)Doi:10.1039/CC9960002097
(1996)Doi:10.1021/jo961289z
(1996)Doi:10.1016/S0040-4039(00)96942-9
(1987)Doi:10.1002/jlac.199619961002
(1996)
