Data for MAS NMR investigation of molecular order in an ionic liquid crystal

The structure and molecular order in the thermotropic ionic liquid crystal (ILC), [choline]+[geranate(H)octanoate]-, an analogue of Choline And GEranate (CAGE) which has potential for use as a broad-spectrum antimicrobial and transdermal and oral delivery agent, were investigated using magic-angle spinning (MAS) nuclear magnetic resonance (NMR), polarizing optical microscopy, small angle X-ray scattering (SAXS) and mass spectrometry. Mass spectrometry and the 1H NMR chemical shift reveal that CAGE-oct is a dynamic system, with metathesis (the exchange of interacting ions) and hydrogen exchange occurring between hydrogen-bonded/ionic complexes such as [(choline)(geranate)(H)(octanoate)], [(choline)(octanoate)2(H)] and [(choline)(geranate)2(H)]. These clusters, which are shown by mass spectrometry to be significantly more stable than expected for typical electrostatic ion clusters, involve hydrogen bonding between the carboxylic acid, carboxylate and hydroxyl groups, with rapid hydrogen bond breaking and reforming observed to average the 1H chemical shifts. The formation of a partial bilayer liquid crystal (LC) phase was identified by SAXS and polarizing optical microscopy at temperatures below ~293 K. The occurrence of this transition close to room temperature could be utilized as a temperature-induced ‘switch’ of the anisotropic properties for particular applications. The presence of an isotropic component of approximately 25% was observed to coexist with the LC phase, as detected by polarizing optical microscopy and quantified by both 1H-13C dipolar-chemical shift correlation (DIPSHIFT) and 1H double-quantum (DQ) experiments. At temperatures above the LC-to-isotropic transition, intermediate-range order (clustering of polar and non-polar domains), a feature of many ILs, persists. Site-specific order parameters for the LC phase of CAGE-oct were obtained from the measurement of the partially averaged 13C-1H dipolar couplings (DCH) by cross-polarization (CP) build-up curves and DIPSHIFT experiments, and 1H-1H dipolar couplings (DHH) by DQ build-up curves. The corresponding order parameters, SCH and SHH, are in the range 0 to 0.2, and are lower compared to those for smectic (i.e., layered) phases of conventional non-ionic liquid crystals, resembling those of lamellar phases formed by lyotropic surfactant-solvent systems. Data record consists of 4 subfolders, organised according to data, and an accompanying readme file. Data files include: raw files from SAXS experiments, raw files from polarising optical microscopy, raw files from MAS NMR experiments, raw files from solution NMR experiments, raw files from IR (ATR), raw files from MS and calculation files. For further information on specific data files please refer to the accompanying readme file.