π-Extended Macrocyclic Oligothiophene Heptamer and Tetradecamer: Ringsize Effects on the Physical Properties and Morphological Features

Abstract

Abstract Synthesis, X-ray structural analysis, redox behavior, and morphological features of π-extended macrocyclic oligothiophene heptamer and tetradecamer are reported. Due to nanophase separation between inner and outer domains, butyl-substituted π-extended macrocyclic oligothiophenes exhibit marked ringsize effects in the solid state. Among macrocycles with the same composition formula, heptamer has a round shape-persistent structure to produce crystals, whereas the corresponding tetradecamer shows morphological diversity to form single crystals, rods, ovals, and balls. The surface structures of small rods, ovals, and balls were investigated by absorption spectra and PXRD analysis. By cyclic voltametric analysis, heptamer and tetradecamer exhibit reversible two-step redox behavior reflecting moderate donor ability, and the first oxidation potentials of heptamer and tetradecamer are roughly consistent with their HOMO levels.