Regio‐regular and cross‐conjugated poly(thienylene vinylene)s through acyclic diene metathesis

Abstract

Poly(thienylene vinylene)s (PTV's) are early examples of conjugated polymers but have not been extensively studied when compared with closely analogous polythiophenes. PTV's synthesized through previously reported techniques are similar in structures that contain various alkyl or alkoxy side-chains that exert limited impact on the polymer electronic properties. Herein, we report the preparation of a series of regio-regular PTV's (rr-PTV's) bearing cross-conjugated sidechains through ADMET polymerization of a common brominated di(thienylene vinylene) (DTV) monomer followed by PPM reactions on the resulting brominated PTV. These new polymers contain a bulky silyloxy alkyl side-chain and a functionalized thiophene moiety on every main-chain thiophene unit, and their regio-regular placement is confirmed by NMR spectroscopy. The thienyl based side-groups broaden polymer absorption ranges and at the same time lead to uncommon emission properties that are results of light-induced charge transfer events between the polymer main-chains and side-chains. Removal of the silyl groups on one of these rr-PTV's led to insoluble materials and x-ray diffraction experiments on the collected solids displayed distinct scattering peaks that are absent from similarly functionalized regio-random PTV's reported previously, thus suggesting better crystallinity originated from regio-regularity.