Structures and solid-state properties of terthiophene cyclic dimers doubly linked by alkyl chains

Abstract

Molecular orientation of pi-conjugated systems has a great influence on their solid-state properties. As a simple strategy for the design of molecular assembly, we now propose the concept of flexible double-chain linkage between two pi-components. A series of terthiophene dimers, in which terthiophene units are linked by two flexible alkyl chains, have been designed and synthesized. These compounds showed significant dependence of their solid-state properties on the linker chain lengths in terms not only of solubility, gelation ability, and phase transition behavior, but also of the solid-state fluorescence. In particular, the difference in the solid-state emission maxima exceeds more than 100 nm between symmetrical parallel dimer and unsymmetrical twisted dimer.