Isomers of beta-substituted di and tri-nitrotetraphenylporphyrins and their copper(II) derivatives: Structure, optical and electrochemical redox properties

Dahal, S and Krishnan, V and Nethaji, M (1998) Isomers of beta-substituted di and tri-nitrotetraphenylporphyrins and their copper(II) derivatives: Structure, optical and electrochemical redox properties. In: Proceddings of The Indian Academy of Sceinces Chemical Sciences, 110 (01). pp. 37-52.

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Abstract

Controlled nitration of meso-tetraphenylporphyrinato copper(II) using fuming nitric acid leads to the formation of different beta-substituted nitro derivatives. Five isomers of dinitro and three isomers of trinitrotetraphenylporphyrins have been isolated and characterised using FAB/MS, H-1 NMR, UV-VIS and IR spectroscopies. The single crystal X-ray data on the copper(II) derivative of one of the isomers of trinitrotetraphenylporphyrin revealed 'saddle' conformation of the porphyrin core resulting from the nitro group substitution at the beta-pyrrole carbons. The electrochemical redox behaviour of the free-base porphyrins and their copper(II) derivatives revealed that successive substitution of nitro groups at the pyrrole carbons shifts the one-electron ring oxidations anodically while the ring reduction occurs at a less cathodic potential relative to the unsubstituted porphyrin. The isomer specific shifts in the redox potentials bear a direct relationship with the relative energy levels of HOMO/LUMO obtained from AM1 calculations.

Item Type:	Journal Article
Additional Information:	Copyright of this article belongs to Indian Academy Of Sciences.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	22 Dec 2009 09:33
Last Modified:	19 Sep 2010 05:25
URI:	http://eprints.iisc.ernet.in/id/eprint/18798

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