Rational Design and Functions of Electron Donor–Acceptor Dyads with Much Longer Charge-Separated Lifetimes than Natural Photosynthetic Reaction Centers

We have found that a directly linked donor­acceptor dyad composed of ZnII and AuIII quinoxalinoporphyrins affords a long-lived charge-shifted state in nonpolar solvents.25

Kei Ohkubo; Shunichi Fukuzumi

2009

Scholarcy highlights

  • Photosynthesis is certainly the most important biological process on earth with respect to light energy conversion, since there would be no food or living creatures without photosynthesis
  • The primary event of photosynthesis at the bacterial photosynthetic reaction center is rapid initial photoinduced electron transfer from a bacteriochlorophyll dimer to bacteriopheophytin on a time scale of 3 ps to produce the primary charge-separated state.1­3 After the primary charge separation, the electron is transferred to a secondary electron acceptor, ubiquinone in about 200 ps
  • When QA is pre-reduced or removed, the primary CS state decays with a lifetime between 3 and 20 ns depending on the species and conditions, which is much longer than the time order of electron transfer to QA despite the much larger driving force
  • The photocatalytic mechanism for the oxygenation of 4,4¤-dimethybiphenyl via photoinduced electron transfer from 4,4¤-dimethylbiphenyl to the singlet excited state of AcrPh+ is clarified based on the dependence of quantum yields on concentrations of substrates and the detected radical intermediates
  • We have found the formation of a 3-complex between a free-base cofacial bisporphyrin and acridinium ion, and examined the photodynamics in PhCN as shown in Scheme 9.69 H4DPOx is regarded as a model compound of a special pair, which has two cofacial porphyrin rings and flexible spacer
  • Acceptor dyad with a short linkage rather than the use of multicomponent systems composed of an electron donor, acceptor, and electron mediator molecules. Rational design of such an electron donor­acceptor dyad based on the Marcus theory of electron transfer has enabled development of a zinc chlorin­ fullerene dyad and 9-mesityl-10-methylacridinium ion as the best compound capable of fast charge separation and extremely slow charge recombination

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