Conformational polymorphs and solid-state polymerization of 9-(1,3-butadiynyl)carbazole derivatives

•Novel two diacetylenes carrying a carbazole group were prepared and characterized by crystallographic analyses.•Two polymorphs were discovered, one of which showed reactivity for solid state polymerization of diacetylenes.•Both diacetylene derivatives gave polydiacetylenes by thermal annealing whose absorption bands extended to near IR region.

The novel diacetylenes, 9-(5-(4-nitrophenoxy)penta-1,3-diyn-1-yl)-9H-carbazole (1) and 4-((5-(9H-carbazol-9-yl)penta-2,4-diyn-1-yl)oxy)benzonitrile (2), were prepared and characterized by crystallographic analyses. Compound 1 gave two conformational polymorphs, 1-(I) and 1-(II), whose differences were concluded to originate in intermolecular interactions among nitrophenyl groups. Crystal 1-(I) and 2 had suitable molecular arrangements for solid-state polymerization and polymerized by thermal annealing to give crystalline polydiacetylenes (PDAs). While an arrangement of 1-(II) was unsuitable for the polymerization. The PDAs showed broad absorption from UV to near IR region (ca. 900 nm), suggesting effective expansion of π-conjugated system by carbazolyl groups.