Design, synthesis and mesomorphic properties of chiral benzoates and fluorobenzoates with direct SmCA-Iso phase transition

• Published in: Liquid crystals 2015-11, Vol.42 (11), p.1601-1611
• Main Authors: Milewska, K., Drzewiński, W., Czerwiński, M., Dąbrowski, R.
• Format: Article
• Language: English
• Subjects: (S)-(+)-2-alcanol; Chemical synthesis; chiral anticlinic smectic; Differential scanning calorimetry; direct SmC; Ferroelectrics; Iso transition; Optical properties; orthoconic antiferroelectric; Phase transitions; synthesis of ester
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2015.1078916

Novel chiral (S)-(+)-4ʹ-(1-methylalkoxycarbonyl)biphenyl-4-yl 4-[ω-(2,2,3,3,4,4,4-heptafluoro-butoxy)alkoxy]benzoates and 4-[ω-(2,2,3,3,4,4,4-heptafluorobutoxy)alkoxy]-2-fluorobenzoates were prepared using different optically active alcohols: (S)-(+)-2-hexanol, (S)-(+)-2-heptanol, (S)-(+)-2-nonanol, (S)-(+)-2-decanol, (S)-(+)-2-undecanol and (S)-(+)-5-methylhexan-2-ol. Properties, such as the sequence of phases, transition temperatures and enthalpies, were tested by polarising optical microscopy and differential scanning calorimetry. Extremely low melting compounds were found (below 10°C) for derivatives of (S)-(+)-2-hexanol. The antiferroelectric smectic phase (SmC A *) with a direct transition from the antiferroelectric to isotropic phase (SmC A *-Iso) was observed, usually for propoxy-(CH 2 ) 3 - spacing group. Initially, multicomponent mixtures with broad temperature ranges of antiferroelectric phase and direct SmC A *-Iso transition were formulated.