Noncovalently Linked Donor-Acceptor Pairings via van der Waals Contacts

NONCOVALENTLY LINKED DONOR-ACCEPTOR PAIRINGS VIA VAN DER WAALS CONTACTS [Pg.317]

Cyclodextrin-appended porphyrins are one of the suitable types of compound for ET models, since cyclodextrin (CD) has a hydrophobic cavity able to capture a small nonpolar molecule such as a quinone in aqueous solution. The fir.st example of a porphyrin- -CD photochemical system 137 was reported by Bolton, Weedon and coworkers in 1984. They monitored the photoinduced ET reaction in a frozen mixture of porphyrin 137 and p-benzoquinone by ESR spectroscopy. Irradiation of the solution showed the characteristic single ESR signal due to the generation of porphyrin cation radical and quinone anion radical species. The signal intensities in the ESR spectra, using a variety of quinones, indicated that the efficiency of the ET depended upon the reduction potential of the quinone acceptors. [Pg.317]

In 1993, Kuroda and coworkers reported a unique porphyrin-quinone system using cyclodextrin-sandwiched porphyrin 138 as a photodonor.In this model. CD is fixed above the porphyrin plane, and the electron acceptor receives an electron from the photoexcited poiphyrin in [Pg.317]

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