Donor−acceptor compounds containing a phenylenediamine electron donor and a naphthalene, a cyanobenzene, or a cyanonaphthalene acceptor were studied. The two chromophores are connected by three different bridging units, consisting of CH 2 groups linked to a semiflexible piperidine or piperazine ring or to a rigid 2,5-diazabicyclo[2.2.1]heptane group. All donor−acceptor compounds show photoinduced charge separation, resulting in the formation of a compact charge-transfer (CCT) state in nonpolar solvents. The conformational change needed to arrive at this species is imposs-
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