Non-planarity and its implications on triplet state characteristics of basket handle porphyrins

✍ Scribed by M. Ravikanth; Damodar Reddy; T.K. Chandrashekar

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 722 KB
• Volume: 222
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)00403-x

✦ Synopsis

The influence of non-planarity in the porphyrin ring on the triplet state characteristics of free base and Zn (II) derivatives of basket handle porphyrins is investigated by triplet ESR. The deviation of the zero-field splitting parameter, D, from planar HsTPP or ZnTPP is dependent on the degree of non-planarity and increases as the non-planarity increases. The electron spin polarization (ESP) pattern for most derivatives remains the same as observed for HsTPP or ZnTPP. However, MSICls, PSIBrs, ZnMSIICls and Znbutyl II show different ESP patterns, suggesting a redirection of the spin sublevel activity in these isomers. The ESP pattern for PSIBrs is temperature dependent (eeaeaa at -160°C and eeeaaa at -106°C). The calculated structure using molecular mechanics reveals maximum deformation in these isomers which in turn governs the population and decay of the triplet sublevels. The structures indicate a different orientation of bridging phenyl groups in PSIBrs and MSICls with respect to the porphyrin plane.