Synthesis and solid-state polymerization of diacetylene derivatives directly substituted with a phenylcarbazole moiety

We synthesized five novel asymmetric carbamate diacetylene (DA) derivatives with a 9-phenyl-9 H -carbazol-3-yl group as an aromatic donor moiety directly bound to the DA. Upon ultraviolet irradiation, three DA derivatives became greenish blue in color and exhibited characteristic excitonic absorption bands, indicating successful regular 1,4-addition polymerization in the solid state to afford polydiacetylenes (PDAs). Among the derivatives, the PDA with the highest conversion exhibited a small ionization potential of 5.2 eV. This value is appropriate for hole injection from general electrodes, and this PDA has the potential for application in low-operating voltage organic electronic devices. Five asymmetric diacetylene carbamates that possessed a 9-phenyl-9 H -carbazol-3-yl (PhCz) group as an aromatic donor that was directly attached to the diacetylene moiety were designed and synthesized. Upon UV irradiation, the highest conversion to the corresponding polydiacetylene was obtained for the benzyl carbamate derivative, and its regular 1,4-addition was confirmed by formation of a greenish-blue polymer that exhibited characteristic excitonic absorption bands. In addition, a small ionization potential of 5.2 eV was observed for this polydiacetylene.