Contrasting Photoinduced Electron-Transfer Properties of Two Closely Related, Rigidly Linked Porphyrin−Quinone Dyads

Autor:	Paul A. Liddell, John P. Sumida, Gilbert R. Seely, Su Lin, Thomas A. Moore, Ana L. Moore, Devens Gust, Alisdair N. Macpherson
Rok vydání:	1998
Předmět:	Solvent Electron transfer chemistry.chemical_compound Reaction rate constant Radical ion Chemistry Molecule Physical and Theoretical Chemistry Photochemistry Porphyrin Photoinduced electron transfer Quinone
Zdroj:	The Journal of Physical Chemistry A. 102:5512-5519
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp980068p
Popis:	Two closely related, rigidly linked porphyrin−naphthoquinone dyads have been prepared and studied using time-resolved fluorescence and absorption methods. Dyad 1, whose quinone carbonyl groups are relatively close to the porphyrin macrocycle, exhibits photoinduced electron-transfer rate constants that are virtually independent of solvent dielectric constant and temperature within the range 77−295 K. Dyad 2, which has a similar donor−acceptor linkage but whose quinone carbonyl groups are ∼2 A farther from the porphyrin, features photoinduced electron-transfer rate constants that decrease with decreasing solvent dielectric constant. Electron transfer in this molecule ceases at low temperatures. Photoinduced electron transfer in dyad 2 exhibits the usual dependence on free energy change and solvent reorganization observed in many similar porphyrin−quinone systems. The behavior of 1 may be attributed at least in part to the smaller separation of the porphyrin radical cation and the quinone radical anion, whic...
Databáze:	OpenAIRE
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