We report a novel self-assembly pathway from a bis(imidazolyl) diphenyl−diacetylene (DPDA) compound as a realization of self-templated photopolymerization with high polymerization degrees. The work takes advantage of a cylindrical self-assembly that strengthens the preorganization of the diphenyl−diacetylene moiety at the single molecular level. On this basis, photopolymerization of DPDA can be conducted smoothly to form high-molecular-weight polydiphenyl diacetylene. Such a cylindrical self-assembly is highly dependent on molecular structure, and control studies show that only oligomers can be formed on random self-assemblies from a monoimidazolyl or nonimidazolyl diphenyl−diacetylene compound. Moreover, the cylindrical self-assembly based systems bear aggregation-induced emission enhancement characteristics and are solution processable. The leading thin-film could afford a selectively tunable function in luminescent micropatterns.
■ INTRODUCTIONAs compared with most conventional diacetylenes with alkyl chains directly connected to the butadiyne unit, the diphenyl− diacetylene (DPDA) moiety with aryl groups attached to the butadiyne has an extended π-conjunction and introduces a large intermolecular stacking tendency. These features generally allow the mesogen as well as the corresponding polydiacetylene species to exhibit more versatile optoelectronic properties, 1−3 implying great interest for their potential exploitation in high birefringence materials, modern display technologies, luminescent emitting diodes, and ideal prototype for molecular devices, etc. 4 Since the first report of diacetylene polymerization in the solid state by Wegner, 5 it has been widely accepted that molecular preorganization is a crucial factor to achieve highly efficient topochemical polymerizations of diacetylene. To drive such an effective polymerization on a diphenyl−diacetylene (DPDA) monomer seems to be difficult, simply because the bulky size of the neighboring phenyl rings in DPDA greatly hampers the minimum movement of the butadiyne moiety. The past decades have witnessed extensive progress in developing many key strategies, based on grafting diacetylene monomers on surface-aligned films or introducing functional groups on the diacetylene monomers to control their aggregation and crystallization, followed by thermal or photochemical polymerization. 6 However, only the formation of oligomers, or even no reaction at all, is observed in most of cases of DPDAs. 7 Gelation and monolayer strategies may somehow promote the polymerization of DPDAs, 8 but they lack solution processability, which will limit large-scale development. A straightforward approach for enhancing the polymerization degree of DPDA in a solution processable manner remains a challenge.Structural-dependent ordered self-assembled nanoarchitectures formed in a certain solvent environment generally show properties distinct from those of their individual constituent molecules, 9 and can even be helpful for improving the chemical reaction behavior. 10 In particular, s...