Synthesis and Characterization of Cyclic Conjugated Architectures Composed of Thiophene and Benzothiadiazole Units

Abstract

Since the conjugated molecules have been developed in past decades, the applications of conjugated molecules to organic electronics have been caught much attention due to their diverse properties and facile fabrication process of flexible devices using printing techniques with low-cost. In this thesis, synthesis and characterization of novel conjugated cyclophanes comprising dialkylthiophene (Th) and benzothiadiazole (BT) linked with vinylenes are reported. The cyclization reaction was achieved by McMurry coupling of Th-BT-Th sequence terminated with two formyl groups. The synthesized compounds in each reaction step were characterized by 1H NMR, GC mass, and FAB mass spectroscopies. The crucial compounds such as cyclophanedienes, cyclophanetrienes, and linear dimer were further identified by 13C NMR and high resolution mass spectroscopies. 1H NMR spectra of cyclophanedienes showed a specific upfield shift of a peak position of BT protons by 0.3 ppm than that of cyclophanetrienes. X-ray single crystallography of one of the cyclophanedienes displayed closed and strained structures and intermolecular π–π stacking at a thiadiazole part in the BT group. The optical and electrochemical properties were examined by measurements of UV-vis and photoluminescence spectra as well as cyclic voltammetry (CV). The cyclic molecules exhibited an absorption band at 444 nm because of charge transfer structures comprising donor-acceptor-donor sequential groups.