Derivatives of 1,2,5-triarylpyrroles bearing phenyl and thiophenyl groups were prepared from their corresponding precursor 1,4-diaryl-1,3-butadiynes. The structure property relationships based on steady state absorption/emission properties and electrochemical properties were investigated for possible applications as synthetic building blocks for π-conjugated active materials in optoelectronic devices. The aryl substituents were altered to explore effects of electron donating (methoxy) and withdrawing groups (fluoro) on electronic structure of the π-system as well as the effects of substitution by thiophene moiety in place of phenyl ring. In addition to the effects of substitution, the effects of annulation on the electronic structures were investigated by comparing pyrroles and their precursor butadiynes.<br/>Butadidyne absorption spectra all show fine features that are separated by ~2200 cm<sup>-1</sup> resulting from vibronic coupling of diyne moiety. Pyrrole derivatives exhibit relatively featureless absorption bands suggesting more flexible nature of the π-system. In addition to change in rigidity upon annulation, π-conjugation of phenyl derivatives seem to suffer more significantly from steric hindrance between the rings than that of thiophene derivative. Although bathochromic shifts of electronic transition bands and lowering oxidation potentials were observed for derivatives with electron donating substituents, photophysical and electrochemical properties of electron withdrawing para-fluorophenyl derivatives do not exhibit significant deviation from its parent phenyl derivatives for pyrroles and butadiynes.

Electrochemical and photophysical structure-property relationship investigation for 1,2,5-triarylpyrroles and their synthetic precursor 1,4-diaryl-1,3-butadiynes

251st National Meeting (2016)

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