Wire-like charge transport at near constant bridge energy through fluorene oligomers

被引:154
作者
Goldsmith, RH
Sinks, LE
Kelley, RF
Betzen, LJ
Liu, WH
Weiss, EA
Ratner, MA
Wasielewski, MR
机构
[1] Northwestern Univ, Dept Chem, Evanston, IL 60208 USA
[2] Northwestern Univ, Ctr Nanofabricat & Mol Self Assembly, Evanston, IL 60208 USA
关键词
electron transfer; hopping; superexchange;
D O I
10.1073/pnas.0408940102
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The study of photoinitiated electron transfer in donor-bridge-acceptor molecules has helped elucidate the distance dependence of electron transfer rates and behavior of various electron transfer mechanisms. In all reported cases, the energies of the bridge electronic states involved in the electron transfer change dramatically as the length of the bridge is varied. We report here, in contrast, an instance in which the length of the bridge, and therefore the distance over which the electron is transferred, can be varied without significantly changing the energies of the relevant bridge states. A series of donor-bridge-acceptor molecules having phenothiazine (PTZ) donors, 2,7-oligofluorene (FLn) bridges, and peryiene-3,4:9,10-bis(dicarboximide) (PDI) acceptors was studied. Photoexcitation of PDI to its lowest excited singlet state results in oxidation of PTZ via the FLn, bridge. In toluene, the rate constants for both charge separation and recombination as well as the energy levels of the relevant FLn+center dot bridge states for n = 1-4 are only weakly distance dependent. After the initial photogeneration of (1)(PTZ(+center dot)-FLn-PDI-center dot), radical pair intersystem crossing results in formation of (3)(PTZ(+center dot)-FLn-PDI-center dot) that recombines to give 3*PDI. The dependence of the (PDI)-P-3* yield on an applied magnetic field shows a resonance, which gives the singlet-triplet splitting, 2J, of the radical ion pair. The magnitude of 2J directly monitors the contribution of coherent charge transfer (superexchange) to the overall electron transfer rate. These data show that charge recombination through FLn is dominated by incoherent hopping at long distances.
引用
收藏
页码:3540 / 3545
页数:6
相关论文
共 52 条
[41]   Effects of initial state preparation on the distance dependence of electron transfer through molecular bridges and wires [J].
Skourtis, S ;
Nitzan, A .
JOURNAL OF CHEMICAL PHYSICS, 2003, 119 (12) :6271-6276
[42]   MAGNETIC-FIELD EFFECTS IN CHEMICAL-KINETICS AND RELATED PHENOMENA [J].
STEINER, UE ;
ULRICH, T .
CHEMICAL REVIEWS, 1989, 89 (01) :51-147
[43]   Mechanism of TMPD photolysis in alcohols. Spin-dependent ion recombination and photoconductivity [J].
Tadjikov, B ;
Smirnov, S .
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2001, 3 (02) :204-212
[44]   Influence of molecular structure on the rate of intersystem crossing in flexible biradicals [J].
Tsentalovich, YP ;
Morozova, OB ;
Avdievich, NI ;
Ananchenko, GS ;
Yurkovskaya, AV ;
Ball, JD ;
Forbes, MDE .
JOURNAL OF PHYSICAL CHEMISTRY A, 1997, 101 (47) :8809-8816
[45]   Charge transport in photofunctional nanoparticles self-assembled from zinc 5,10,15,20-tetrakis(perylenediimide)porphyrin building blocks [J].
van der Boom, T ;
Hayes, RT ;
Zhao, YY ;
Bushard, PJ ;
Weiss, EA ;
Wasielewski, MR .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2002, 124 (32) :9582-9590
[46]   WHAT CAN BE LEARNED FROM THE SINGLET-TRIPLET SPLITTING OF THE RADICAL PAIR P+H- IN THE PHOTOSYNTHETIC REACTION-CENTER - CONCLUSIONS FROM ELECTRIC-FIELD EFFECTS ON THE P+H- RECOMBINATION DYNAMICS [J].
VOLK, M ;
HABERLE, T ;
FEICK, R ;
OGRODNIK, A ;
MICHELBEYERLE, ME .
JOURNAL OF PHYSICAL CHEMISTRY, 1993, 97 (38) :9831-9836
[47]   PHOTOINDUCED ELECTRON-TRANSFER IN SUPRAMOLECULAR SYSTEMS FOR ARTIFICIAL PHOTOSYNTHESIS [J].
WASIELEWSKI, MR .
CHEMICAL REVIEWS, 1992, 92 (03) :435-461
[48]   Making a molecular wire:: Charge and spin transport through para-phenylene oligomers [J].
Weiss, EA ;
Ahrens, MJ ;
Sinks, LE ;
Gusev, AV ;
Ratner, MA ;
Wasielewski, MR .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2004, 126 (17) :5577-5584
[49]   MECHANISM AND SPIN-DYNAMICS OF PHOTOINDUCED ELECTRON-TRANSFER REACTIONS [J].
WELLER, A .
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-WIESBADEN, 1982, 130 (02) :129-138
[50]   MAGNETIC-FIELD EFFECTS ON GEMINATE RADICAL-PAIR RECOMBINATION [J].
WELLER, A ;
STAERK, H ;
TREICHEL, R .
FARADAY DISCUSSIONS, 1984, 78 :271-278