Solid-state dynamics in the closo-carboranes: a (11)B MAS NMR and molecular dynamics study.

This work explores the dynamic behavior of the three closo-carborane isomers (formula C2B10H12) using modern solid-state magic angle spinning (MAS) NMR techniques and relates the experimental measurements to theoretical results obtained using molecular dynamics simulations. At high temperatures and at B0 = 9.4 T, the (11)B MAS line widths are narrow (40-90 Hz) for the three isomers.

Counterion and composition effects on discotic nematic lyotropic liquid crystals II. Ion exchange and molecular dynamics.

The static fluorescence quenching of pyrene by bromide, at the interface of mixed TTAC/TTAB discotic nematic lyotropic liquid crystals, allowed an estimation of the equilibrium constant for the exchange of chloride by bromide. The affinity of the interface for bromide is much higher than for chloride (K(Br-/Cl-) = 13.2).

Counterion and composition effects on discotic nematic lyotropic liquid crystals I. Size and order.

Counterion and composition effects on the size and interface dynamics of discotic nematic lyotropic liquid crystals made of tetradecyltrimethylammonium halide (TTAX)-decanol (DeOH)-water-NaX, with X = Cl(-) and Br(-), were investigated using NMR and fluorescence spectroscopies. The dynamics of the interface was examined by measuring deuterium quadrupole splittings from HDO (0.1% D(2)O in H(2)O) and 1,1-dideuterodecanol (20% 1,1-dideuterodecanol in DeOH) in 27 samples of each liquid crystal.