Structure de la phase cristalline à température ambiante (20°C) du dérivé bis-p-butylanilino de l'acide téréphtalique (TBBA). I
Résumé
The crystal structure at room temperature (20°C) of TBBA has been solved; this compound gives rise to several liquid-crystal forms at higher temperatures. A model for the disorder of the butyl side chains is proposed. This disorder is probably connected with the transition point at 113°C which leads to a smectic Β form. The lattice parameters of the low-temperature crystalline form have been determined. At 20°C TBBA crystallizes in the monoclinic system, C2/c, Z = 8, with a = 53.2 (±0.1), b = 5.75 (±0.005), c = 17.57 (±0.003) Å, β = 115.47 (±0.05)°. MULTAN and a full-matrix least-squares refinement have been employed. Final R and Rω values are 0.133 and 0.167 for the 4020 reflexions. The two butyl side chains have only been partially refined since disorder does not allow an accurate description.
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