Room-temperature monoclinic and low-temperature triclinic phase-transition structures of meso-octamethylcalix [4] pyrrole-dimethyl sulfoxide (1/1)

Lynch, Vincent M., Gale, Phillip A., Sessler, Jonathan L. and Madeiros, David (2001) Room-temperature monoclinic and low-temperature triclinic phase-transition structures of meso-octamethylcalix [4] pyrrole-dimethyl sulfoxide (1/1). Acta Crystallographica Section C: Crystal Structure Communications, 57 (12), 1426-1428. (doi:10.1107/S0108270101015931).

Abstract

Crystals of the title complex, C28H36N4.C2H6OS, undergo a phase transition between room temperature and 198 K, as determined by X-ray diffraction techniques. A monoclinic form is observed at room temperature, while a triclinic modification is found at 198 K, with Z' changing from 1 to 2. Differential scanning calorimetry (DSC) of the calixpyrrole- dimethyl sulfoxide complex revealed a series of phase changes between 273 and 243 K. The transition from the room-temperature monoclinic form to the low-temperature triclinic form is reversible, as determined by changes in the cell dimensions from remeasuring selected reflections at room temperature and at temperatures below 223 K. The uncomplexed calix[4]pyrrole molecule shows no phase changes occurring between room temperature and 233 K, the low-temperature limit of the DSC.

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Contributors

Author: Phillip A. Gale

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