The nematic twist-bend phase (NTB) was, until recently, only observed for polar mesogenic dimers, trimers or bent-core compounds. In this article, we report a comprehensive study on novel apolar materials that also exhibit NTB phases. The NTB phase was observed for materials containing phenyl, cyclohexyl or bicyclooctyl rings in their rigid-core units. However, for materials with long (>C7) terminal chains or mesogenic core units comprising three ring units, the NTB phase was not observed and instead the materials exhibited smectic phases. One compound was found to exhibit a transition from the NTB phase to an anticlinic smectic C phase; this is the first example of this polymorphism. Incorporation of lateral substitution with respect to the central core unit led to reductions in transition temperatures; however, the NTB phase was still found to occur. Conversely, utilising branched terminal groups rendered the materials non-mesogenic. Overall, it appears that it is the gross molecular topology that drives the incidence of the NTB phase rather than simple dipolar considerations. Furthermore, dimers lacking any polar groups, which were prepared to test this hypothesis, were found to be non mesogenic, indicating that at the extremes of polarity these effects can dominate over topology.

Successful identification of complex odors by sensor arrays remains a challenging problem. Herein, we report robust, category-specific multiclass-time series classification using an array of 20 carbon nanotube-based chemical sensors. We differentiate between samples of cheese, liquor, and edible oil based on their odor. In a two-stage machinelearning approach, we first obtain an optimal subset of sensors specific to each category and then validate this subset using an independent and expanded data set. We determined the optimal selectors via independent selector classification accuracy, as well as a combinatorial scan of all 4845 possible four selector combinations. We performed sample classification using two modelsa k-nearest neighbors model and a random forest model trained on extracted features. This protocol led to high classification accuracy in the independent test sets for five cheese and five liquor samples (accuracies of 91% and 78%, respectively) and only a slightly lower (73%) accuracy on a five edible oil data set.

Can the interplay between steric and electronic properties induced by end-groups be used to dictate self-organisation in soft materials?

All chemicals were used as received, without purification with the exception of bromobenzene, which was distilled prior to use. Column chromatography was performed using Fluka 70-230 silica gel, dry vacuum flash chromatography (DVFC) [S1] was performed using Merck 15111 silica gel. Solvents were dried by passage through a column of activated alumina prior to use. NMR spectra were recorded on a JEOL ECX spectrometer operating at 400 MHz ( 1 H) or 100.5 MHz ( 13 C), with the residual protic solvent used as the internal standard in all cases. Mass spectra were recorded on a Bruker micrOTOF MS-Agilent series 1200LC spectrometer (ESI) or a Waters GCT Premier mass spectrometer (EI). FTIR spectroscopy was performed using a Shimadzu IR Prestige-21 with Specac Golden Gate diamond ATR IR insert. High-performance liquid chromatography was performed on a Shimadzu Prominence modular HPLC system comprising a LC-20A liquid chromatograph, a DGU-20A5 and DGU-20B degasser, a SIL-20A autosampler, a CBM-20A communication bus, a CTO-20A column oven, and a SPO-20A dual wavelength UV-vis detector. The column used was an Alltech C18 bonded reverse-phase silica column with a 5 μm pore size, an internal diameter of 10 mm and a length of 250 mm, acetonitrile was used as the mobile phase in each case. Polarised optical microscopy was performed on a Zeiss Axioskop 40Pol microscope using a Mettler FP82HT hotstage controlled by a Mettler FP90 central processor.Photomicrographs were captured with aid of an InfinityX-21 MP digital camera. Differential scanning calorimetry was performed on a Mettler DSC822 e fitted with an autosampler operating with Mettler Star e software and calibrated before use each day using an indium standard (onset = 156.55 ± 0.2 °C, ΔH = 28.45 ± 0.40 Jg -1 ) under an atmosphere of dry nitrogen. Computational studies were performed using GAMESS-UK [S2] for ab initio calculations (B3LYP and MP2) and MOPAC 2012 [S3] for semi-empirical calculations (AM1, PM6). Synthetic Pathway Scheme 1 1,7-bis(4-Methoxyphenyl)heptane-1,7-dione (i1 -3)A catalytic quantity of DMF (0.1 ml) was added to a stirred suspension of pimelic acid (i1 -1, 17.5 g, 0.109 mmol) and oxalyl chloride (40 g, 27 ml, 0.32 mol) in anhydrous DCM (300 ml) under an atmosphere of dry argon resulting in the vigorous evolution of gas. The reaction was monitored by the evolution of gas, and was stirred for a further 30 minutes after the cessation of effervescence, at which point the solvent and excess oxalyl chloride was removed in vacuo. The crude pimeloyl chloride obtained (i1 -2) was added dropwise to a stirred, cooled (0 °C) suspension of aluminium chloride (42.6 g, 0.32 mmol) and anisole (34.6 g, 35 ml, 0.32 mol) in anhydrous DCM (500 ml) under an atmosphere of dry argon. The pimeloyl chloride was added at such a rate that the temperature of the reaction did not exceed 5 °C. The reaction was stirred overnight and quenched by pouring onto ice. The organic layer was separated and washed with sodium hydroxide (2 M, 2 x 200 ml), water (2 x 100 ml) and brine (2 x 200 ml...