Interactions and dynamics of mesogenic molecules in the vicinity of the isotropic to nematic phase transition

A role of the molecular structure and polarity in the dielectric behavior of nematogenic compounds in the vicinity of the isotropic to nematic phase transition is discussed. Temperature dependences of the static permittivity and its derivative, in relation to the basic thermodynamic quantities (internal energy, entropy and Helmholtz free energy), as well as an anomaly in the rotational diffusion of the mesogenic molecules and corresponding activation energy, are analyzed.