Brooks, L and Brunelli, M and Pattison, P and Jones, GR and Fitch, A (2015) Crystal structures of eight mono-methyl alkanes (C26-C32) via single-crystal and powder diffraction and DFT-D optimization. IUCrJ, 2 (Pt 5). 490 - 497. ISSN 2052-2525

[img]
Preview
Text
Crystal structures of eight mono-methyl alkanes (C26-C32) via single-crystal and powder diffraction and DFT-D optimization.pdf - Published Version

Download (1MB) | Preview

Abstract

The crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species, e.g. ants, wasps etc. The molecules were synthesized as pure S enantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66. All crystallize in space group P21. Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10° from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials.

Item Type: Article
Uncontrolled Keywords: mono-methyl alkanes, powder diffraction, synchrotron radiation, DFT-D, single-crystal diffraction, insect pheromones
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 17 Dec 2015 09:38
Last Modified: 14 Jul 2017 09:46
URI: http://eprints.keele.ac.uk/id/eprint/1306

Actions (login required)

View Item View Item