Stoichiometric imbalance-promoted synthesis of polymers containing highly substituted naphthalenes: rhodium-catalyzed oxidative polycoupling of arylboronic acids and internal diynes

A new route for the synthesis of functional polymers was developed. Oxidative polycoupling of 4,4'-(alpha,omega-alkylenedioxy) bis(diphenylacetylene)s with phenylboronic acid and (1,1,2-triphenylvinyl)phenylboronic acid, respectively, was catalyzed by [Cp*RhCl2](2) and oxidants in dimethylformamide, affording soluble polymers with highly substituted naphthalene rings in satisfactory yields with moderate molecular weights. All the polymers were thermally and morphologically stable, showing high thermal-degradation and glass-transition temperatures of 317-404 degrees C and 95-168 degrees C, respectively. They were film-forming and their thin solid films showed high refractive indices (RI = 1.7414-1.6038) in a wide wavelength region of 400-1600 nm. The polymer carrying tetraphenylethene unit was weakly emissive in solution but emitted intensely in the condensed phase, displaying a phenomenon of aggregation-induced emission. The emission of its nanoaggregates could be quenched by picric acid with large quenching constants, making it promising as a sensitive chemosensor for efficient detection of explosives.