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Porphyrins Appended with Podand Side Arm. Evidence for the Existence of Folded Conformer

Maiya, Bhaskar G and Krishnan, V (1983) Porphyrins Appended with Podand Side Arm. Evidence for the Existence of Folded Conformer. In: Inorganica Chimica Acta, 77 . L13-L15.

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Recent years have witnessed the synthesis of porphyrins with peripheral substituents, essentially directed towards the development of models for the ligand binding affinities of heme moieties and cytochrome activity [l] . The design of organic substituents to the porphyrins must of necessity contain potentially ligating terminal group, viz. a nitrogeneous base that can effectively coordinate to the metal centre thereby blocking one of the faces of the porphyrins for entry to other molecules. The driving force necessary to fold the side arm over the porphyrin ring has been the coordinative interaction between the terminal group and the metal centre. Our interest has been to induce conformational mobility to the side arm so as to promote intra-molecular interaction between the terminal group and the porphyrin chromophore. We present here information on the synthesis of porphyrins endowed with a side arm of variable length consisting of $-OCH_2CH_2O-$ groups appended to meta or para position of the phenyl group situated in one of the meso positions of the porphyrin and the side arm terminating with an aryl group. Optical and ESR data of the synthesised porphyrins provide evidence for the existence of folded conformers. The advantages of the ESR method include the fact that changes in the electronic manifold of the spin-free metal as a consequence of CT interaction can easily be reflected in the change in values and hypertine coupling constants. Besides, cyclic voltammetric studies of the synthesised porphyrins have been helpful in determining the ease of ring oxidation and difficulty in reduction as compared to the tetraphenylporphyrin.

Item Type: Journal Article
Publication: Inorganica Chimica Acta
Publisher: Elsevier
Additional Information: The copyright belongs to Elsevier
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 20 Jun 2008
Last Modified: 19 Sep 2010 04:46
URI: http://eprints.iisc.ac.in/id/eprint/14400

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