Solid-state (35)Cl NMR (SSNMR) spectroscopy is shown to be a useful probe of structure and polymorphism in HCl pharmaceuticals, which constitute ca. 50% of known pharmaceutical salts. Chlorine NMR spectra, single-crystal and powder X-ray diffraction data, and complementary ab initio calculations are presented for a series of HCl local anesthetic (LA) pharmaceuticals and some of their polymorphs. (35)Cl MAS SSNMR spectra acquired at 21.1 T and spectra of stationary samples at 9.4 and 21.1 T allow for extraction of chlorine electric field gradient (EFG) and chemical shift (CS) parameters. The sensitivity of the (35)Cl EFG and CS tensors to subtle changes in the chlorine environments is reflected in the (35)Cl SSNMR powder patterns. The (35)Cl SSNMR spectra are shown to serve as a rapid fingerprint for identifying and distinguishing polymorphs, as well as a useful tool for structural interpretation. First principles calculations of (35)Cl EFG and CS tensor parameters are in good agreement with the experimental values. The sensitivity of the chlorine NMR interaction tensor parameters to the chlorine chemical environment and the potential for modeling these sites with ab initio calculations hold much promise for application to polymorph screening for a wide variety of HCl pharmaceuticals.

A novel bent-rod hexacatenar liquid crystal is reported that displays a hexagonal columnar (Col h ) phase. The organization of conjugated hexacatenar mesogens in the columnar phase is of interest for their anisotropic electronic properties. The emissive nature of the mesogens varies over the temperature range of the Col h phase and the spectral shifts were analyzed in terms of an exciton-coupling model. The variation of the emission band in this phase is consistent with varying degrees of rotational disorder between the mesogens. The bent-rod shape and highly dipolar nature of the liquid crystal core (mesogen) promotes (as suggested by computation, X-ray diffraction, and photophysical studies) a high degree of antiparallel intermolecular correlations between nearest neighbors. The antiparallel organization is novel and differs from structures previously identified in other polycatenars. These studies illustrate the utility of the exciton-coupling model to probe the nature and degree of intermolecular correlations in highly dipolar liquid crystals.

Reported here are the unique properties of N,N 0 ,N 00 -(3,4,5-tridodecyloxyphenyl)benzo[b,b 0 , b 00 ]tristhiophene-2,2 0 ,2 00 -tricarboxamide 3 as a new H-bonded discotic liquid crystal. Polarized optical microscopy and thermal analysis as well as variable temperature IR spectroscopy and X-ray diffraction confirm the presence of two thermotropic H-bonded hexagonal columnar mesophases that cover a temperature range from <-50 to 280 °C. Intermediate lyotropic mesophases of the highly viscous material aid the alignment of the hexagonal columnar mesophases, which is essential for a detailed structural characterization and applications. Solutions of 3 in heptane at concentrations as low as 1 wt % display isotropic organo-gel phases that consist of H-bonded networks of 3 but do not contain columnar stacks. 2D-X-ray diffraction studies on aligned samples of the thermotropic hexagonal columnar mesophases and DFT calculations on a tetramer of 3 reveal a helical columnar stacking of the individual benzotristhiophene units. Charge carrier mobility measured by time-resolved microwave conductivity is about 0.02 cm 2 V -1 s -1 in both hexagonal columnar mesophases and quasi temperature independent even across the phase transition between the two mesophases. The temperature independence is explained by the interrelation between stacking distance and mutual rotation because of the persistent intracolumnar H-bonds between amide groups. Half-life of the charge carriers, on the other hand, drastically increases in the low temperature hexagonal columnar mesophase, which is most likely a result of changing molecular dynamic and conformational states of the side chains. DFT calculations of the frontier orbitals show that the benzotristhiophene core is the sole contributor to the LUMO but does not contribute to the HOMO, whereas the trialkoxyaniline groups are the sole contributors to the HOMO. This suggests that the observed combined mobility is that of electrons alone because no hole transport is expected to occur between trialkoxyaniline groups that are spaced apart by more than 4 A ˚. Indeed, an electron mobility of 2 Â 10 -3 cm 2 V -1 s -1 but no transient signal for hole transport is obtained by timeof-flight charge carrier mobility measurements on a multi domain sample of 3.

Ionic discotic liquid crystals are salts of discotic liquid crystals that may display lyotropic and thermotropic mesomorphism. Columnar structures of π‐π stacking ionic discotic liquid crystals function not only as anisotropic organic semiconductors, similar to their neutral analogues, but they may also efficiently conduct ions. This combination of electronic and ionic conduction is only one of several unique properties that these materials may display, but their systematic investigation has been limited because of their often complex synthesis, purification, and characterization. However, a comprehensive account of existing reports on ionic discotic liquid crystals is not straightforward, despite their relatively small number, because publications are scattered across different areas of research, such as liquid crystals, ionic liquids, and ionic self‐assembly. This review intends to provide a concise but comprehensive overview of the published work on ionic discotic liquid crystals and related compounds and is expected to stimulate further exploration. Highlighted in this review is the mesomorphism of ionic discotic liquid crystals and its dependence on structural changes, which is also the focus of most reported studies. Particular attention was given to the dependence of mesomorphism on the location and types of the charged groups as these are parameters unique to these compounds. Also described are electronic, optical, and other properties of these materials if reported.