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The Crystal and Molecular Structure of Mesogenic Malonates
Author(s) -
Körner H.,
Zugenmaier P.
Publication year - 1993
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170280825
Subject(s) - mesogen , chemistry , crystallography , alkoxy group , crystal structure , antiparallel (mathematics) , stereochemistry , molecule , phase (matter) , alkyl , organic chemistry , liquid crystalline , physics , quantum mechanics , magnetic field
The crystal and molecular structures of diethylene‐6‐[4‐(4′‐nitrophenylazo)phenoxy]dodecylmalonate (12 PhNO 2 ) and ‐propylmalonate (3 PhNO 2 ) were determined with CuK α to a = 19.235(5) Å, b = 7.620(1) Å, c = 22.400(4) Å; α = 90°, β = 103.27(1)°, γ = 90°; space group P2 1 /c for 12 PhNO 2 and a = 6.797 (6) Å, b = 7.756 (8) Å, c = 22.74(2) Å; α = 81.48(7)°, β = 88.29(7)°, γ = 68.10(9)°; space group P 1 for 3 PhNO 2 . Refinement with 1130 observed reflections (> 3σ) for 12 PhNO 2 and 1615 for 3 PhNO 2 leads to R (12 PhNO 2 ) = 5.8% and R (3 PhNO 2 ) = 4.4%. The molecular conformation in the crystalline state is the most extended trans conformation for both compounds. On rapidly cooling from the isotropic melt, 12 PhNO 2 shows a smectic A‐phase. In agreement with prior investigations on polar mesogens, the molecules arrange in an antiparallel packing. The azo‐mesogen is nearly coplanar with the alkoxy spacer up to the branching atom. The low molecular weight malonates investigated may serve as model compounds for side‐group liquid crystalline polymers.