Controlling Electron Transfer in Donor−Bridge−Acceptor Molecules Using Cross-Conjugated Bridges
| Autor: | Michael T. Colvin, Amy M. Scott, Kun Chen, Gemma C. Solomon, Michael R. Wasielewski, Annie Butler Ricks, Mark A. Ratner |
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| Rok vydání: | 2010 |
| Předmět: |
Anthracenes
Electron Spin Resonance Spectroscopy Diphenylmethane General Chemistry Naphthalenes Conjugated system Photochemical Processes Photochemistry Biochemistry Electron transport chain Acceptor Catalysis Absorption Electron Transport chemistry.chemical_compound Electron transfer Colloid and Surface Chemistry chemistry Molecular conductance Thermodynamics Spectroscopy Julolidine |
| Zdroj: | Journal of the American Chemical Society. 132:15427-15434 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja107420a |
| Popis: | Photoinitiated charge separation (CS) and recombination (CR) in a series of donor-bridge-acceptor (D-B-A) molecules with cross-conjugated, linearly conjugated, and saturated bridges have been compared and contrasted using time-resolved spectroscopy. The photoexcited charge transfer state of 3,5-dimethyl-4-(9-anthracenyl)julolidine (DMJ-An) is the donor, and naphthalene-1,8:4,5-bis(dicarboximide) (NI) is the acceptor in all cases, along with 1,1-diphenylethene, trans-stilbene, diphenylmethane, and xanthone bridges. Photoinitiated CS through the cross-conjugated 1,1-diphenylethene bridge is about 30 times slower than through its linearly conjugated trans-stilbene counterpart and is comparable to that observed through the diphenylmethane bridge. This result implies that cross-conjugation strongly decreases the π orbital contribution to the donor-acceptor electronic coupling so that electron transfer most likely uses the bridge σ system as its primary CS pathway. In contrast, the CS rate through the cross-conjugated xanthone bridge is comparable to that observed through the linearly conjugated trans-stilbene bridge. Molecular conductance calculations on these bridges show that cross-conjugation results in quantum interference effects that greatly alter the through-bridge donor-acceptor electronic coupling as a function of charge injection energy. These calculations display trends that agree well with the observed trends in the electron transfer rates. |
| Databáze: | OpenAIRE |
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