Anna Bellusci

UV/Vis to NIR photoconduction in cyclopalladated complexes.

The incorporation of a rigid core, formed by a cyclopalladated azobenzene fragment bonded to an ancillary Schiff base ligand, into molecules with 12 or 11 peripheral alkyl chains has been successfully achieved. These new complexes, 1 and 2, respectively, are columnar liquid crystals between room temperature and about 50 degrees C. Both cyclometallated and ancillary ligands have been polyalkylated through either aryl ester (electron-withdrawing group) or aryl ether (electron-releasing group) linkages, in order to tune the HOMO/LUMO energy levels. The photoconductive properties of 1 and 2 have been studied as a function of their absorption properties before and after annealing, from the UV/Vis to NIR region. Compared with the reference compounds, tris-alkynyl benzene discotics, these new materials gave similar performances (sigma/I approximately 8x10(-13) S cm W(-1) with E = 10 V microm(-1) at lambda = 370 nm). Moreover, complex 2 shows a normalized photoconductivity sigma/I = 8.5x10(-13) S cm W(-1) at lambda = 760 nm. Organic photoconductors in such a high wavelength spectral range are not common and are usually assembled by mixing dyes with organic semiconductors.

Copper(II) and Nickel(II) Complexes of a Tetradentate Ligand Containing an N,N′-Bis(Salicylidene)Dodecane-1, 10-Diamine Core

The synthesis of mesomorphic Cu(II) and Ni(II) coordination compounds arising from a new series of tetradentate Schiff bases containing two salicylaldimine fragments connected by a very long spacer,-(CH2)12-, (H2Ln): L1 = p-(C6H13O)-C6H4COO, L2 = p-(C12H25O)-C6H4COO, is described. The self-assembly and liquid-crystalline properties of these complexes have been investigated by variable temperature powder X-ray diffraction and the relationship between the global molecular shape and the mesogenic performances is discussed. The reported Cu(II) compounds are molecular materials which could be of interest for applications in the field of magnetic molecule-based devices.

Room temperature columnar mesomorphism and high quantum yield phosphorescence in ionic ruthenium(II) 2,2′-bipyridine-based complexes

The induction of columnar mesomorphism in ionic heteroleptic octahedral tris-2,2′-bipyridine Ru(II) complexes, through a modulation in the ligand structure, produces a large effect on the phosphorescence quantum efficiency (Φ = 0.14) demonstrating that the synthesis of a liquid crystalline compound containing a hexacoordinated Ru(II) chromophore is a helpful strategy in the design of room temperature multifunctional soft materials, very appealing for light-emitting electrochemical cells or solid-state photovoltaic cells applications.

Thermotropic Mesomorphism in Salen-like Zinc Complexes

The reaction between a series of non mesogenic tetradentate salen-like Schiff bases and Zn(II) acetate gives rise to the formation of liquid cristalline complexes showing nematic and smectic phases stable over a quite large temperature range. A dimeric structural arrangement could favour the appearance of such type of mesophase in the case of 1,3-diaminopropane and 1,3-diamino-2,2-dimethylpropane bridges containing ligands while for the salen derivatives a monomeric solvent-induced pentacoordinated arrengement observed in solution and in the crystalline molecular structure, probably prevent the liquid crystalline behaviour.

Supramolecular Columnar Mesomorphism Induced by Silver(I) Coordination of 2,2′-bipyridine-4,4′-diamides

ABSTRACT The synthesis and characterization of novel ionic liquid crystals displaying columnar mesomorphism induced upon complexation of 2,2′-bipyridine-4,4′-disubstituted ligands ( L n ) are reported. A tetracoordination around the silver( I ) centre has been obtained for the first time in metallomesogens based on chelated bipyridine ligands. The molecular organization in the mesophase for these [ Ag ( L n ) 2 ][ OTf ] derivatives is strongly dependent on the coordination and ionic bonds which drive the supramolecular assembly.

Liquid Crystalline Cholesterol-Based Ortho-Palladated Curcumin Complexes as Multifunctional Biomaterials

Mononuclear ortho-palladated complexes containing 2-phenylquinoline ligand functionalized with a chiral entity and a biologically active O,O chelated ligand have been synthesized and fully characterized. The evaluation of the liquid crystalline properties of these non-conventional compounds is reported in view of a potential use of these organometallic systems in generating new bifunctional biomaterials.

Intermolecular interactions and nano-segregation in the modulation of liquid crystalline properties of molecular materials

FA4-MS07-O3 Intermolecular Interactions and Nano-Segregation in the Modulation of Liquid Crystalline Properties of Molecular Materials. Alessandra Crispinia, Daniela Puccib, Iolinda Aiellob, Anna Belluscib, Mauro Ghedinib. aDepartment of Pharmaceutical Science, University of Calabria Italy. bCentro di Eccellenza CEMIF.CAL-LASCAMM, CR-INSTM Unità della Calabria; Department of Chemistry, University of Calabria, Italy. E-mail: a.crispini@unical.it