Effect of substituents and alkoxy chain length on the phase behaviour and optical properties of 4-substituted-phenyl 4-alkoxybenzoates

The refractive indices as functions of temperature were measured for 4-substituted-phenyl 4-alkoxybenzoates 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 was either CH3O, CH3, Cl, CN or NO2. Polarizing optical microscopy was also used to identify mesophases and measure their transition temperatures. The results are discussed in terms of electronic polarizability effects.