Liquid Crystalline Samples: Orientational Order of Small Rigid Solutes in Nematic Mesophases

Conformational and Orientational Determination from Dipolar Couplings in a Weakly Ordering Organic-Based Lyotropic and a Strongly Ordering Thermotropic Liquid Crystal

“…The very small value of S cc means that c axis (very "rigidly" oriented of t-St/ZLI1132) randomly samples about all the possible orientations with about the same probability. This demonstrates that the short-range interactions, by now commonly recognized as the dominant orientational mechanism [2,[71][72][73][74] are substantially different for the two phases. In PBLG phase, in particular, the S cc ∼ = 0 seems to indicate intuitively that the molecular tumbling about the a and b axes should be rather free (or at least less hindered), which is not the case in ZLI1132 nematic liquid crystal phase.…”

“…Since the pioneering work of Saupe and Englert in 1963, [1] liquid crystals proved to be very attractive media for NMR studies of solutes dissolved therein [2][3][4]. In these media, the anisotropic part of the NMR interactions (chemical shift anisotropy, indirect spin-spin coupling anisotropy, dipolar coupling, and quadrupolar splitting) becomes observable and can give direct access to molecular properties.…”

“…In these media, the anisotropic part of the NMR interactions (chemical shift anisotropy, indirect spin-spin coupling anisotropy, dipolar coupling, and quadrupolar splitting) becomes observable and can give direct access to molecular properties. In particular, the analysis of order, structure and conformational equilibrium of flexible molecules starting from experimental dipolar couplings D ij gained much attention thanks to the plenty of applications and fields of interest [2][3][4][5]. For this purpose, many different liquid crystalline phases have been explored, that can be roughly divided depending on the degree of orientational order they induce to the solute.…”

Recent NMR Studies of Thermotropic Liquid Crystals

“…A comprehensive review of this topic over the last five decades has recently appeared [335], from which the reader can follow both the historical and theoretical developments of solute studies in anisotropic fluids. Another recent review deals with NMR techniques and theoretical tools used to study solutes dissolved in LCs [336].…”