Consequently, it can be concluded that the HOMO-LUMO energy gap decreases from 4T to 6T, which is consistent with the bathochromic shift observed for the longest-wavelength absorption maxima. In summary, we have developed synthetic routes to 5T and 6T via Suzuki-Miyaura cross-coupling and a nickel-mediated homocoupling reactions that involved the synthesis of a new β,βʹ-substituted moiety 2. Using an excess of 3 effectively suppressed the formation of polymers. While only a single singlet was observed in the NMR spectra of 4T and 5T, three different signals were observed for 6T. The solid-state structures of 5T and 6T were determined using X-ray crystallography; a corresponding analysis of the metric parameters revealed that the smallest dihedral angle of the 3,3ʹbithiophene moiety decreases with increasing number of thiophene rings. The size-dependence observed in the NMR spectra can be rationally interpreted in terms of the activation energies for the interconversion of the thiophene rings. The size-dependence manifests in the optoelectronic measurements, in which the longest-wavelength absorption maxima are by 13 nm bathochromically shifted with increasing size of the molecules. The results of our DFT calculations suggest that gradually increasing the number of thiophene rings gradually increases the HOMO energy and decreases the LUMO energy. With synthetic routes to 5T and 6T established, it will now be possible to explore the synthetic chemistry of a variety of unprecedented π-conjugated thiophene-containing arenes.