Crystal and Molecular Structure of a Mesogenic Compound with a Large Lateral Benzene Ring-containing Substituent

Abstract

The crystal and molecular structure of the nematic compound 4-nitrobenzyl 2,5-bis (4-ethyloxybenzoyloxy)-benzoate (NEBB) has been determined at −100°C and at room temperature by X-ray analysis. NEBB crystallizes in space group P 1 with two molecules in a unit cell of dimensions (values of the room temperature investigation are given in brackets) a = 9.547 (3) [9.643 (2)], b = 12.294 (4) [12.452 (3)], c = 13.536 (5) [13.660 (3)] Å, α = 68.67 (3) [68.34(1)], β= 75.15 (3) [74.40 (1)], γ = 70.98 (3) [69.65 (1)]°. The structure was solved by direct methods and refined on F ² to R values of wR2 = 0.107 [0.109] and R1 = 0.043 [0.049], respectively, for 3347 [2422] observed unique reflections.

The phenylene bis(benzoate) basic core of the NEBB molecule has a non-planar but optimally stretched shape and the lateral ring-containing substituent is oriented parallel to it. The molecules in the crystalline state are arranged perfectly parallel to each other with an anti-parallel orientation of the neighbours. They form lamellar sheets and a tilted layer structure.

Key Words:

• Crystalline mesogens
• X-ray analysis
• molecular structure
• crystal packing
• laterally branched mesogens
• phenylene bis(benzoates).