Please use this identifier to cite or link to this item: http://localhost:8080/xmlui/handle/123456789/1090
Title: Modified 26 and 28 pi hexaphyrins with five meso-links: Optical, redox, and structural properties
Authors: Gokulnath, S
Prabhuraja, V
Suresh, C H
Chandrashekar, T K
Keywords: Aromaticity
Conformation analysis
Redox chemistry
Issue Date: 2009
Publisher: Wiley
Citation: Chemistry- An Asian Journal 4(6):861-869;02 Jun 2009
Abstract: The syntheses of new aromatic 26 pi and non-aromatic 28 pi hexa-phyrins through a [4+2] acid catalyzed condensation of easily available and air-stable precursors are reported. Both 26 pi and 28 pi hexaphyrins are reversibly transformed into one another by two-electron reduction with NaBH(4) or two-electron oxidation with dichlorodicyanobenzoquinone (DDQ) respectively. Detailed optical and NMR spectral studies suggests that the [26]hexaphyrin is aromatic and possesses a diatropic ring current, while [28]hexaphyrin exhibits non-aromatic characteristics. The structural characterization has been done with extensive (1)H and 2D NMR Studies. Theoretical calculations performed with various conformational possibilities tested for the unsubstituted hexaphyrin, at semiempirical level, sug-gest that the most stable conformation takes an inverted structure with one pyrrole ring inversion. The energy optimization for the final geometry of the unsubstituted hexaphyrin, performed at the B3LYP/6-31G* level of DFT, shows excellent agreement with the structure derived from the solution NMR data. Electrochemical data reveals HOMO destabilization with increasing pi-electron conjugation consistent with the large red shifts of the absorption bands.
ISSN: 1861-4728
Appears in Collections:2009

Files in This Item:
File Description SizeFormat 
2009 _00091.pdf
  Restricted Access
732.73 kBAdobe PDFView/Open Request a copy

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.