The influence of molecular shape and electronic properties on the formation of the ferroelectric nematic phase. [Dataset]

Abstract

The synthesis and characterisation of two series of ferroelectric nematogens based on RM734 having an additional methoxy group on the central phenyl ring are reported, the 3-methoxy-4-((4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (7-m-n) and the 3-methoxy-4-((3-fluoro-4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (8-m-n). In order to compare the behaviour of these series to those of the corresponding materials that do not contain the methoxy group on the central phenyl ring, we also report the synthesis and characterisation of 4-[(4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (11-0-1), 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (12-0-1) and 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-diethoxybenzoate (12-2-2). Two compounds in which a lateral ethoxy chain is attached to the central ring, 3-ethoxy-4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (18-2-1) and 3-ethoxy-4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (19-2-1), are also described. The behaviour of these materials shows that the relative stabilities of the ferroelectric nematic, NF, and conventional nematic, N, phases are governed by a subtle interplay of steric and electronic factors. Furthermore, the electronic factors are better understood in terms of isolated regions of electron density rather than by a single large longitudinal dipole moment. In terms of molecular shape, to observe the NF phase it appears that the molecular structure must include one or more lateral substituents that enhance molecular biaxiality and destabilise the N phase. The accompanying file with this output contains supplementary material.

Citation

CRUICKSHANK, E., TUFAHA, N., WALKER, R., BROWN, S., GORECKA, E., POCIECHA, D., STOREY, J.M.D. and IMRIE, C.T. The influence of molecular shape and electronic properties on the formation of the ferroelectric nematic phase. [Dataset]. Liquid crystals [online], 51(3), pages 401-415. Available from: https://doi.org/10.1080/02678292.2024.2304598

• Acceptance Date: Jan 2, 2024
• Online Publication Date: Jan 25, 2024
• Publication Date: Mar 15, 2024
• Deposit Date: Jan 29, 2024
• Publicly Available Date: Jan 29, 2024
• Publisher: Taylor and Francis
• DOI: https://doi.org/10.1080/02678292.2024.2304598
• Keywords: Ferroelectric nematic phase; Fluorine; Lateral substituents; Liquid crystals; Nematic phase
• Public URL: https://rgu-repository.worktribe.com/output/2225335
• Related Public URLs: https://rgu-repository.worktribe.com/output/2218701 (Journal article)
• Type of Data: Docx file of addition information, figures and tables
• Collection Date: Jan 2, 2024
• Collection Method: Reagents: All reagents and solvents that were available commercially were purchased from Sigma Aldrich, Fisher Scientific or Fluorochem and were used without further purification unless otherwise stated. Thin Layer Chromatography: Reactions were monitored using thin layer chromatography, and the appropriate solvent system, using aluminium-backed plates with a coating of Merck Kieselgel 60 F254 silica which were purchased from Merck KGaA. The spots on the plate were visualised by UV light (254 nm). Column Chromatography: For normal phase column chromatography, the separations were carried out using silica gel grade 60 Å, 40-63 μm particle size, purchased from Fluorochem and using an appropriate solvent system. Structure Characterisation: All final products and intermediates that were synthesised were characterised using 1H NMR, 19F NMR, 13C NMR and infrared spectroscopies. The NMR spectra were recorded on a 400 MHz Bruker Avance III HD NMR spectrometer. The infrared spectra were recorded on a Perkin Elmer Spectrum Two FTIR with an ATR diamond cell. High Resolution Mass Spectrometry: In order to determine if the molecular ions of the final products or their adducts were present, high-resolution mass spectrometry was carried out using a Waters XEVO G2 Q-Tof mass spectrometer by Dr. Morag Douglas at the University of Aberdeen.