Self-assembly of functional molecular systems based on intramolecular charge-transfer compounds

Abstract

Highly polarized compounds exhibiting intramolecular charge transfer (ICT) are used widely as nonlinear optical (NLO) materials and red emitters and in organic light emitting diodes. Low-molecular-weight donor/acceptor (D/A)-substituted ICT compounds are ideal candidates for use as the building blocks of hierarchically structured, multifunctional self-assembled supramolecular systems. This paper describes our recent studies into the development of functional molecular systems with well-defined self-assembled structures based on charge-transfer (CT) interactions. We have developed new methods to synthesize ICT compounds through the introduction of heterocycles or heteroatoms to the π-conjugated systems or through extending the conjugation of diverse aromatic systems via another aromatic ring. For example, we obtained a noncentrosymmetric microfiber structure that possessed a permanent dipole along its fibers’ long axis and a transition dipole perpendicular to it; the independent NLO responses of this material can be separated and tuned spectroscopically and spatially. The encouraging results that we have obtained suggest that such self-assembled ICT molecular materials can guide the design of new nanostructures and materials from organic systems, and that these materials, across a range of compositions, sizes, shapes, and functionalities, can potentially be applied in the fields of electronics, optics, and optoelectronics.