title: Multifunctional supramolecular dendrimers with an s-triazine ring as the central core: liquid crystalline, fluorescence and photoconductive properties.
abstract: Novel liquid crystal (LC) dendrimers have been synthesised by hydrogen bonding between an s-triazine as the central core and three peripheral dendrons derived from bis(hydroxymethyl)propionic acid. Symmetric acid dendrons bearing achiral promesogenic units have been synthesised to obtain 3:1 complexes with triazine that exhibit LC properties. Asymmetric dendrons that combine the achiral promesogenic unit and an active moiety derived from coumarin or pyrene structures have been synthesised in order to obtain dendrimers with photophysical and electrochemical properties. The formation of the complexes was confirmed by IR and NMR spectroscopy data. The liquid crystalline properties were investigated by differential scanning calorimetry, polarising optical microscopy and X-ray diffractometry. All complexes displayed mesogenic properties, which were smectic in the case of symmetric dendrons and their complexes and nematic in the case of asymmetric dendrons and their dendrimers. A supramolecular model for the lamellar mesophase, based mainly on X-ray diffraction studies, is proposed. The electrochemical behaviour of dendritic complexes was investigated by cyclic voltammetry. The UV/Vis absorption and emission properties of the compounds and the photoconductive properties of the dendrons and dendrimers were also investigated.
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias-Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza (Spain).
authors.forename: Madalina
authors.initials: M
authors.lastname: Bucoş
authors.forename: Teresa
authors.initials: T
authors.lastname: Sierra
authors.forename: Attilio
authors.initials: A
authors.lastname: Golemme
authors.forename: Roberto
authors.initials: R
authors.lastname: Termine
authors.forename: Joaquín
authors.initials: J
authors.lastname: Barberá
authors.forename: Raquel
authors.initials: R
authors.lastname: Giménez
authors.forename: José Luis
authors.initials: JL
authors.lastname: Serrano
authors.forename: Pilar
authors.initials: P
authors.lastname: Romero
authors.forename: Mercedes
authors.initials: M
authors.lastname: Marcos
keywords: dendrimers; fluorescence; hydrogen bonds; liquid crystals; photoconductivity