Covalent dimers choice

Of course, the influence of the bridge on the degree of electronic coupling appears to be an excellent way to promote electron transfer from a donor to an acceptor. Fukuzumi, Kadish, and Crossley have reported the use of covalently linked chromophores in which electronic coupling is enhanced by a bridge that allows a coplanar orientation of the donor and the acceptor. In addition to the choice of a biphenyl type link, in which each phenyl is fused with the tetrapyrrolic rings, the subtlety of the hybrid dimer 23 depicted in Figure 13.24 is the use of a nonneutral dyad. 

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