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This work reports new soft photothermal materials based on liquid crystalline nickel bis(dithiolene) complexes bearing pentakis(dodecyloxy)triphenylene units in which the triphenylene core and the metal complex are linked through -(CH2)n- (n = 2, 4, 10) connectors. The mesomorphic properties of these materials can be modulated by the length of the linker. All the complexes, except the derivative with the longest linker, show columnar mesomorphism, characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray scattering studies. The structure of the mesophases contains segregated organic and inorganic columns supported respectively by π-stacking of the triphenylene discs and weak intermolecular nickel-sulfur interactions. The photothermal activity was studied on the complex with n = 2. Under laser irradiation with a power density of 0.098 W cm-2 for just over a minute an increase in temperature of ΔT = 50 °C was achieved. This produced the melting of the crystalline solid to give rise to the columnar mesophase, where, interestingly, the photothermal effect was enhanced. Quantum chemical calculations have also been performed to gain insight into the supramolecular self-assembled columnar structure at the molecular level, as well as into the photothermal behavior. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of three bent-rod dimers are reported. Very long flexible spacers that include methylene units and either a phenyl ring or a triazole moiety as connecting structures join the bent- and rod-promesogenic cores. Polarizing microscopy, modulated differential scanning calorimetry, X-ray diffraction at variable temperature and dielectric measurements have been performed to establish the mesophase behaviour of the dimers. The results show a complex supramolecular organization for this kind of flexible dimer in the mesophase. Interestingly, the length and the chemical nature of the flexible linking spacers condition the liquid crystalline properties of these novel compounds. Additionally, it has been found that the chemical structure of the rod-like core plays a key role in determining the kind of mesophase, either nematic or lamellar, formed by these materials. [ABSTRACT FROM AUTHOR]