Quantitative evaluation of soluble polymeric photosensitizers V: norbornadiene—quadricyclene conversion photosensitized by polymer-bound (benzyloxy)-benzaldehyde
✍ Scribed by R. Martinez-Utrilla; F. Catalina; R. Sastre
- Book ID
- 103991631
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 649 KB
- Volume
- 44
- Category
- Article
- ISSN
- 1010-6030
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✦ Synopsis
Soluble polymeric photosensitizers based on oand p-(benzyloxy)benzaldehyde and the corresponding monomeric model compounds were studied as triplet energy donors to norbornadiene. The results are interpreted with the assumption that a triplet exciplex is formed as an intermediate in the route to quadricyclene. The subsequent excip'tex decomposition yields triplet norbomadiene which finally isomerizes to quadricyclene. The studied o-and p-substituted monomeric model compounds give exciplex decomposition efficiencies of about 0.5. On the other hand, the polymeric samples give lower exciplex formation efficiencies than the free sensitizers, in parallel with previous results obtained with stilbene. Phosphorescence spectra were measured at 77 K. The para compound has a phosphorescence quantum efficiency much greater than the ortho compound, very likely owing to the intramolecular cyclization undergone by the triplets of the ortho compounds. Polymer binding enhances the phosphorescence of both o-and psubstituted chromophores.