C3‐symmetrical, alkoxyphenyl substituted 2,5,8‐(tris‐1,3,4‐oxadiazol‐2‐yl)benzo [1,2‐b; 3,4‐b′; 5,6‐b′′]trithiophenes (OXD‐BTT) are synthesized via threefold Huisgen‐reaction. A broad variation of alkoxy substitution pattern and chain lengths is reported. The thermal behavior was investigated via differential scanning calorimetry (DSC), polarized optical microscopy (POM) and thermogravimetry (TGA). Optical properties were studied via UV‐Vis and fluorescence spectroscopy. Structural information of the LC phases was gained from X‐ray diffraction on oriented fibers. OXD‐BTT provide enormous phase widths (ΔT≥289 K) with clearing points close to thermal decomposition. Most of the derivatives exhibit two different mesophases, the lower phase with a rectangular 3D‐structure and a hexagonal 2D‐lattice at higher temperature. The variation of the chain length allows a tuning of melting and clearing points. OXD‐BTT emit blue light with fluorescence quantum yields up to 30 % in good solvents. The emission is very sensitive to aggregation, thus, in poor solvents the emission intensity decreases, and red shift of maxima occurs.
Star-shaped compounds are widely recognized as emerging materials for optical and electrical applications and as scaffolds of discotic liquid crystal. While the C3-symmetrical tri(phenylthienyl)benzene is the core for several electroopotical materials, no liquid crystal with this scaffold has yet been reported. Acid-catalyzed cyclocondensation of bromoacetylthiophene gives a C3-symmetrical star, threefold Suzuki coupling results in extension of the conjugated system. With 3,4-didodecylocyphenyl boronic acid, a star with a large rigid conjugated system and flexible aliphatic periphery is obtained. Differentials scanning calorimetry and polarized optical microscopy reveal an enantiotropic mesophase from 66 °C to 106 °C.
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