Abstract
The crystal structures of four liquid-crystal (LC) compounds belonging to 4-acylphenyl 4′-alkyloxybenzoates with the general formula C n H2n + 1-C(O)-C6H4-O-C(O)-C6H4-O-C m H2m + 1 numbered as 1/6, 1/7,2/7, and 3/7 (the numbers in the code indicate the ratios of the numbers of alkyl-chain units, n/m) are determined. Compounds 1/6 and 1/7 form smectic and nematic phases, but they are monotropic mesogens, whereas compounds 2/7 and 3/7 form only an enantiotropic smectic phase. Compound 3/7 crystallizes in two crystal modifications—triclinic with Z′ = 2 (3/7 tr ) and monoclinic with Z′ = 4 (sp. gr. P2, 3/7 mon ). All crystals consist of alternating aromatic and aliphatic regions and are characterized by the presence of weak directional interactions, such as C-H...O hydrogen bonds and π-stacking interactions. This provides the necessary conditions for the formation of a mesophase, and the existence of two types of structure-forming units is in line with the formation of a smectic phase. An explanation is proposed for the monotropic properties of 1/6 and 1/7.
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Original Russian Text © I.I. Konstantinov, A.V. Churakov, L.G. Kuz’mina, 2013, published in Kristallografiya, 2013, Vol. 58, No. 1, pp. 89–100.
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Konstantinov, I.I., Churakov, A.V. & Kuz’mina, L.G. Molecular and crystal structures of 4-acylphenyl 4′-alkyloxybenzoates. Crystallogr. Rep. 58, 81–92 (2013). https://doi.org/10.1134/S1063774513010082
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DOI: https://doi.org/10.1134/S1063774513010082