Carbon-13 NMR measurements of the chemical shifts are reported as a function of temperature for a semi-phasmidic molecule 4-(2,3,4-tridecyloxy-phenylazo)-benzoic acid (TDPABA). The data indicate a dimer structure in the solution and suggest a similar structure also in the nematic phase, which is con- sistent with it being a phasmid-like liquid crystal. The orientational order parameters are derived in the nematic phase based on the carbon shielding tensors calculated by Density Functional Theory. The nema- tic order parameter Szz is found to be (relatively) higher for TDPABA than that found in a typical calamitic liquid crystal, likely due to its underlying columnar phase.
NMR study of a phasmid-like liquid crystal
GEPPI, MARCO;
2011-01-01
Abstract
Carbon-13 NMR measurements of the chemical shifts are reported as a function of temperature for a semi-phasmidic molecule 4-(2,3,4-tridecyloxy-phenylazo)-benzoic acid (TDPABA). The data indicate a dimer structure in the solution and suggest a similar structure also in the nematic phase, which is con- sistent with it being a phasmid-like liquid crystal. The orientational order parameters are derived in the nematic phase based on the carbon shielding tensors calculated by Density Functional Theory. The nema- tic order parameter Szz is found to be (relatively) higher for TDPABA than that found in a typical calamitic liquid crystal, likely due to its underlying columnar phase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
