Twisted intramolecular charge transfer (TICT) states are reviewed, and their relation to the more general model of biradicaloid charge transfer states (BCT) is shown. Examples include donor-acceptor-stilbenes where twisting can occur around single and/or double bonds. Another kind of multidimensionality is encountered in systems where different donor goups are linked to one acceptor. This is exemplified with a series of benzopyrylium dyes. Finally, symmetric biaryl systems are shown to be molecular models for understanding some of the intriguing questions of photosynthesis (orthogonality of the chromophores, inequivalence ofL andM electron transfer paths).

The photophysical properties ofp-cyano-N,N-dimethylaniline (CDMA) and its derivatives in various surroundings are reviewed. New results on the luminescence in the solid phase near liquid helium temperature and in a supersonic beam are presented.