Topochemical Polymerization of a Diacetylene in a Chalcogen-Bonded (ChB) Assembly

The successful topochemical polymerization of bis(selenocyanatomethyl)butadyine 1 is achieved upon association in a 1 : 1 co-crystal with 1,2-bis(2-pyridyl)ethylene (2-bpen) through strong and linear (NC)-Se...N-Py chalcogen bonding (ChB) interactions, allowing for an appropriate parallel alignment of the diacetylene moieties toward the solid-state reaction. Co-crystal 1.(2-bpen) undergoes polymerization upon heating at 100 degrees C. The reaction progress was monitored by IR, DSC and PXRD. An enhancement of the polymer conductivity by 8 orders of magnitude is observed upon iodine doping. Strikingly, the course of polymerization is accompanied with sublimation of the ChB acceptor molecules 2-bpen, providing the polymer in a pure form with full recovery of the co-former, at variance with the usual hydrogen-bonded co-crystal strategies toward polydiacetylenes.

Automated summary

Successful topochemical polymerization of bis(selenocyanatomethyl)butadyine 1 was achieved through the formation of a co-crystal with 1,2-bis(2-pyridyl)ethylene (2-bpen). The co-crystal underwent polymerization upon heating and the ChB acceptor molecules 2-bpen sublimated during the reaction. The polymer showed enhanced conductivity after iodine doping.