Thiophene-Fused 1,10-Phenanthroline and Its Conjugated Polymers

A novel type of π-extended 1,10-phenanthroline, specifically with fused thiophene groups at the less exploited 3-, 4-, 7-, and 8-positions of the phenanthroline ring, and its conjugated polymers were designed and synthesized. The current developed route is based on the Bischler–Napieralski cyclization of the (1,2-phenylene)diamide precursor, which offers a facile and versatile strategy for preparing soluble and well-defined 1,10-phenanthroline derivatives and their analogues. High molecular weight poly(phenanthroline- co -fluorene)s with good solubility in common organic solvents or water were prepared by palladium-catalyzed Suzuki–Miyaura–Schlüter polycondensation. The optical responsive properties of these thiophene-fused 1,10-phenanthroline-containing polymers have demonstrated these polymers could be a good candidate for potential applications as luminescent chemosensor materials thanks to the specific repeating unit along the backbone.