Phase behaviour of nematic and non-nematic binary systems IV-P-terphenyl and its analogues in 5CB

If there are suitable molecular interactions between nematic and non-nemati c molecules and the resulting complexes have suitable length-to-width ratio , nematic-isotropic phase transition temperature (T-NI) can rise contrary t o usually observed fall. This types of rise in T-NI were observed in binary systems composed of 5CB and aromatic acids, and were ascribed to the forma tion of hydrogen bonded complexes between 5CB solvent and non-nematic solut es [1-3]. We newly found that the T-NI rose in the binary systems in which there can not be expected to exist any hydrogen-bonded complexes. We studied the poss ibility of the complex formation by molecular interactions other than inter molecular hydrogen bonding between 5CB and non-nematic solutes. Their conse quences on thermal properties of binary systems were investigated.