Short-chain basket handle porphyrins: Singlet and triplet excited state properties

✍ Scribed by Damodar Reddy; T.K. Chandrashekar; Hans van Willigen

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 553 KB
• Volume: 202
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)85360-z

✦ Synopsis

The excited state properties of the title compounds and their Zn ** derivatives, determined by fluorescence and photoexcited tnpled ESR methods, are reported. Fluorescence spectral studies indicate that the basket handle porphyrins are less fluorescent than the parent meso-tetraphenyl porphyrin (H,TPP). The combined effects of intersystem crossing and internal conversion account for this difference. Estimated excited state potentials suggest that the cross trans linked isomer (PSI) is a better electron donor in the first singlet excited state. Zero-field splitting parameters D and E of the three isomers evaluated from photoexcited triplet ESR show small but significant differences attributed to distortion ofthe porphyrin plane caused by introduction of a short bridging group. The electron spin polarization (ESP) pattern remains the same as in H,TPP, indicating the usual spin-orbit coupling mechanism for intersystem crossing.