Polymer structures are defined by three basic characteristics: constitution, configuration and conformation. Whereas first two of them apply mostly to monomer units, the molecular conformation defines the ability of the macromolecules to form superstructures with unique physical and chemical properties. In particular, coplanar conformation of the backbone of conjugated polymers facilitates their <i>π</i>-stacking with formation of ordered packing in the solid state. These structures are extensively used in “plastic electronics” such as thin-film transistors (TFTs), organic light-emitting diodes (OLEDs), and photovoltaics.<br/>Most of the known π-conjugated oligomers and polymers are composed of multiple aromatic rings connected by one single bond each with other. Steric repulsion and thermodynamic fluctuations prevent formation of coplanar structures due to low activation energy for dynamic torsional motion of a single bond. Some recent papers report applications of dynamic bridging intramolecular interactions for conformational control of the conjugated molecules. These interactions include hydrogen bonds, acid-base and metal coordination and heteroatom non-covalent interactions.<br/>Here we report the design and chrystallographical characterization of series of twelve novel three ring fluorinated compounds with S-F and N-F non-bonding intramolecular interactions. In addition to previously described bis-thiophene-phenylene system, a library of its thiazole analogues with different degree of fluorination of the central phenylene ring were prepared. Their solid state structures were studied with X-ray crystallography and compared with reported analogues. Introduction of electron poor thiazole (in contrast with electron rich thiophene) allows to enhance π-π stacking in solid state with significantly shorter interplanar distances.

Design and structural study of fluorinated 1,4-di(thiazolyl)benzenes as monomers for π-conjugated polymers with enhanced coplanarity

256th National Meeting (2018)

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