Effect of substituents and alkoxy-chain length on the phase behavior of 4-substituted phenyl-4-alkoxybenzoates

摘要

Four series of 4-substituted phenyl-4-alkoxybenzoates were prepared in which one substituent is a terminal alkoxy group with the number of carbon atoms kept constant (at n = 6, 8, 14, or 16), while the other terminal substituent (X) alternatively changed from CH3O, CH3, Cl, CN, and NO2, Compounds prepared were characterized by infrared spectroscopy and their mesophase stabilities investigated by differential scanning calorimetry and polarized-light microscopy. The results were discussed in terms of mesomeric, polarity, and polarizability effects. In all four series, the mesophase-isotropic transition temperatures (T-c) were successfully related to the polarizability anisotropy of bonds to the small compact substituent, X. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 21]