title: Search for microscopic and macroscopic biaxiality in the cybotactic nematic phase of new oxadiazole bent-core mesogens.
abstract: The possibility of biaxial orientational order in nematic liquid crystals is a subject of intense current interest. We explore the tendencies toward local and global biaxial ordering in the recently synthesized trimethylated oxadiazole-based bent-core mesogens with a pronounced asymmetric (bow-type) shape of molecules. The combination of x-ray diffraction and optical studies suggests that the biaxial order is expressed differently at the short- and long-range scales. Locally, at the scale of a few molecules, x-ray-diffraction data demonstrate biaxial packing. However, above the mesoscopic scale, the global orientational order in all three compounds is uniaxial, as evidenced by uniform homeotropic alignment of the nematic phase which is optically tested over the entire temperature range and by the observations of topological defects induced by individual and aggregated colloidal spheres in the nematic bulk.
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Greta
authors.initials: G
authors.lastname: Cukrov
authors.affiliation: Dipartimento di Scienze e Ingegneria della Materia, dell'Ambiente ed Urbanistica and CNISM, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vita
authors.affiliation: Department of Chemistry, University of Puget Sound, 1500 N. Warner, Tacoma, Washington 98416, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Scharrer
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Edward T
authors.initials: ET
authors.lastname: Samulski
authors.affiliation: Dipartimento di Scienze e Ingegneria della Materia, dell'Ambiente ed Urbanistica and CNISM, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: Oriano
authors.initials: O
authors.lastname: Francescangeli
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Oleg D
authors.initials: OD
authors.lastname: Lavrentovich