Une étude cristallographique: superspace description of a commensurate composite cocrystal of 4,4′-dinitrobiphenyl and biphenyl

Abstract

We report the structure of a 3 : 1 cocrystal of 4,4′-dinitrobiphenyl and biphenyl. The cocrystal can be regarded as a commensurate column composite crystal and therefore is described in superspace. The structure is monoclinic at 100 K (superspace group C2(σ₁0σ₃)0), but undergoes a single-crystal-to-single-crystal phase transition upon cooling, which results in a triclinic distortion at 20 K (C1(σ₁σ₂σ₃)0). Unlike similar symmetry-lowering phase transitions, this transition is not found to induce twinning. Other structurally similar cocrystals with 4,4′-dinitrobiphenyl and small organic molecules have been reported in the literature demonstrating that 4,4′-dinitrobiphenyl is prone to form composite crystals.