Structure and Solid-State Polymerization of 1,6-Bis(3',6'-dibromo-N-carbazolyl)-2,4-hexadiyne

Abstract

Crystals of 1,6-bis(3',6'-dibromo-N-carbazolyl)2,4-hexadiyne (DCHBr4, la) belong to the monoclinic system, space group P2 1 /c, with a = 15.408(5) A, b = 4.120(1) A, c = 20.032(6) A, β = 95.72-(3)°, V = 1265.3(11) A 3 , and Z = 2. Full-matrix least-squares refinement of positional and displacement parameters for all atoms (H atoms fixed at calculated positions), with 1570 reflections (I > 1.96σ(I)) led to R = 0.0469 and R w = 0.0448. The crystal structure of DCHBr 4 consists of linear chains of molecules stacked along the crystallographic b axis with an orientation similar to that reported earlier for 1,6-di-N-carbazolyl-2,4-hexadiyne (DCH, 1b) at T 200 °C leads to solid-state polymerization of this monomer accompanied by thermal decomposition ; 3,6-dibromocarbazole was identified as a volatile product of the latter process. The color change accompanying the solid-state polymerization of DCHBr 4 suggests applications for this monomer as an irreversible thermochromic sensor. The product of the solid-state reaction is a poly(diacetylene), as determined from resonance Raman spectroscopic measurements.