BN-embedded oligo- and poly(thiophene iminoborane)s: dipole-aligned isosteres of poly(thiophene vinylene) with efficient room-temperature phosphorescence.

The substitution of C[double bond, length as m-dash]C units by isoelectronic and isosteric B[double bond, length as m-dash]N motifs in π-conjugated systems has emerged as a powerful strategy to access materials with tailored optoelectronic properties. Herein, we report the first strictly BN-alternating poly(thiophene iminoborane), representing a boron-nitrogen isostere of poly(thiophene vinylene). The BN-PTV is obtained via AB-type polycondensation of monomers bearing complementary B and N termini, which also enables the synthesis of monodisperse oligomers comprising up to three BN units. The BN-alternating oligomers and polymer exhibit efficient π-conjugation and markedly enhanced emission compared to previously reported BBNN-type analogues. In addition, they display aggregation-induced or -enhanced emission (AIE/AEE), as well as low-temperature phosphorescence and efficient room-temperature phosphorescence (RTP) in inert PMMA matrices. These results establish BN-embedded PTV analogues as a promising platform for the design of advanced conjugated materials with tunable photophysical properties.