Crystal structure and mesogenic behaviour of a new fluorene derivative: 9,9-dimethyl-2,7-bis(4-pentylphenyl)-9H-fluorene.

The title compound, CH, is a new mesogenic compound containing the fluorene moiety. It exhibits enantiotropic nematic liquid crystalline behaviour with melting at 125 °C and isotropization at 175 °C. The crystallographically independent unit contains two molecules oriented face-to-edge with respect to each other.

Relaxation dynamics and crystallization study of glass-forming chiral-nematic liquid crystal S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl 9H-fluorene (5P-AmFLAm-P5).

The chiral nematic S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl9H-fluorene (5P-AmFLAm-P5) liquid crystal shows a complex phase diagram strongly dependent on thermal treatment as identified by Polarizing Optical Microscopy (POM) and differential scanning calorimeter (DSC). The molecular dynamics in various thermodynamics states was studied by means of broadband dielectric spectroscopy (BDS). The vitrification of a chiral nematic phase (N) is manifested by a Vogel-Fulcher-Tammann (VFT)-type temperature dependence of structural relaxation time ([Formula: see text]).

Interplay between Crystallization and Glass Transition in Nematic Liquid Crystal 2,7-Bis(4-pentylphenyl)-9,9-diethyl-9 H-fluorene.

This article presents the crystallization behavior and molecular dynamics of the supercooled nematic state of the newly synthesized liquid crystal 2,7-bis(4-pentylphenyl)-9,9-diethyl-9 H-fluorene (5P-EtFLEt-P5) studied by means of broadband dielectric spectroscopy (BDS). 5P-EtFLEt-P5 is a fragile glass-forming system with a high fragility parameter ( m ≈ 121). The study compares the isothermal melt- and cold-crystallization processes at several selected temperatures T in the vicinity of the glass-transition temperature T (1.