Dipolar Dye Aggregates: A Problem for Nonlinear Optics, but a Chance for Supramolecular Chemistry

Abstract

Highly dipolar merocyanine dyes such as 1 form strong dimer aggregates with an antiparallel orientation of their dipole moments in solution. Substituent variations and solvent-dependent binding studies have shown that the aggregation is driven by electrostatic dipole–dipole interactions and that the dyes are prevented from orienting in an applied electric field by the presence of the large internal field within the dipolar aggregate.