SYSTEMATIC STUDY OF A SERIES OF HIGHLY FLUORESCENT ROD-SHAPED DONOR-ACCEPTOR SYSTEMS

The synthesis and emissive properties of bichromophoric molecules 1-11 are reported. All systems contain an anilino group as a one-electron donor (D) and various substituted ethylene moieties as electron acceptor (A) separated by a rod-shaped alicyclic framework provided by a piperidine ring. From the emissive properties it is concluded that in these molecules the electronic coupling between D and A is sufficient to allow complete charge transfer upon excitation (if thermodynamically feasible). The dipolar charge-transfer (CT) excited state thus populated displays a very strong fluorescence, which is highly solvatochromic (i.e., undergoes a large wavelength shift in response to changes of the solvent polarity), making these systems of interest as a new class of fluorescent probes. Variation of the acceptor group is found to allow design of such probes, with quantum yield vs solvent polarity profiles optimized for any particular polarity range. © 1990, American Chemical Society. All rights reserved.