Synthesis, Mesomorphic Properties and Application of (R,S)-1-Methylpentyl 4′-Hydroxybiphenyl-4-carboxylate Derivatives

Abstract

Thirteen new liquid crystalline racemic mixtures were synthesized and investigated. For these racemic mixtures, the phase sequences and their changes were determined by polarizing optical microscopy (POM). The phase transition temperatures and transition enthalpies were checked by differential scanning calorimetry (DSC). All new racemates have an anticlinic smectic CA phase in a broad temperature range. Three highly tilted antiferroelectric mixtures were doped with six racemates at a concentration of 20% by weight. The helical pitch of the prepared mixtures was measured by the spectrophotometry method. All doped mixtures have a longer helical pitch than the base mixtures.

Properties of Antiferroelectric Mixtures Differing in the Amount of Added Racemate

“…The temperature ranges of the SmC* phase are wider by 1.2 °C, 0.5 °C, and by 0.3 °C for the mixtures W-462, W-463, and W-464, respectively, compared to the mixture W-1000. The temperature ranges of the SmA* phase are wider by 1.5 °C, 1.4 As expected, adding optically inactive mesogen to the base mixture causes an increase in the helical pitch in the SmC A * phase, which has been observed previously [33][34][35][40][41][42].…”

“…In the SmC* phase, the pitch values are outside the measurement range of the spectrophotometer used. As expected, adding optically inactive mesogen to the base mixture causes an increase in the helical pitch in the SmCA* phase, which has been observed previously [33][34][35][40][41][42].…”

“…The racemates can be successfully used as components or admixtures for the antiferroelectric chiral mixtures, which has also been demonstrated in other works [40][41][42].…”

The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases

“…The ferroelectric phase (SmC*) was predicted and then discovered by Meyer et al in 1975 [13], and antiferroelectricity in liquid crystals was discovered by Chandani et al in 1989 [14]. Practical applications have only liquid-crystalline mixtures [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] because the composition's tuning allows us to make the optimized ferro-or antiferroelectric mixtures. It is not easy to synthesize compounds with the desired properties.…”