Optically Active Mesogenic Dispiro[2.0.2.1]Heptane Derivatives and their Unusual Physical Properties

• Published in: Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals Vol. 364; no. 1; pp. 253 - 270
• Main Authors: Miyazawa, Kazutoshi, Demus, Dietrich, Meijere, Armin De
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.08.2001; Gordon and Breach
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; dispiro[2.0.2.1]heptane; Exact sciences and technology; Experimental determinations of smectic, nematic, cholesteric, and other structures; ferroelectric; helical twist; Liquid crystals; Liquids and liquid crystals; Liquids, emulsions, and suspensions; liquid crystals; Physics; spontaneous polarization; Structure of solids and liquids; crystallography; Molecular form; Transition temperature; Smectic crystals; Phase transformations; Doping; Chemical structure; Binary systems; Experimental study; Liquid crystals; Physical properties; Helicity; Molecular orientation; Ferroelectric materials; Response time; Chirality; Chemical preparation; Optical materials; Dispirane; Spontaneous polarization
• ISSN: 1058-725X
• DOI: 10.1080/10587250108024994

Physical properties, i.e. phase transition temperatures, response times, Ps values, tilt angles, helical twisting powers and helical twisting senses of a series of novel ferroelectric liquid crystalline compounds with non-substituted and halogen-substituted dispiro[2.0.2.1]heptyl moieties in their side chains have been measured. When mixed with an achiral SmC base mixture, the resulting SmC* mixtures containing the novel compounds showed ferroelectricity, and the novel compounds were estimated as useful dopants for ferroelectric liquid crystal mixtures. Further unusual properties were observed with the combinations of the two diastereomeric novel compounds, for example (1S,3R,4S)-4a and (1S,3R,4R)-5a. They showed opposite signs for the Ps and the same sense for the N* helical twisting, which clearly suggests that the direction of the Ps and helical sense of N* must be derived from different origins.