Tris(5‐aryl‐1,3,4‐oxadiazolyl)benzotrithiophenes – Discotic Liquid Crystals with Enormous Mesophase Ranges

Abstract

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.

Oxadiazole-integrated heterocoronene discotics as ambipolar organic semiconductors

“…Thus, the OXD units are capable of stabilizing the columnar architecture at high temperatures, preventing disorder in the assembly and enabling efficient stacking of the discs through additional dipolar interactions. 34,35 Also, the phase transitions for 1.1–1.3 were reproducible across several heating and cooling cycles (under POM), advocating the sustainable nature and thermal stability of the columnar assembly of the mesophase. Furthermore, thermogravimetric analysis (TGA) was performed to determine the thermal stability.…”

New Benzotrithiophene-Based Molecules as Organic P-Type Semiconductor for Small-Molecule Organic Solar Cells

“…Discotic stacking in BTT derivatives has been previously reported in the literature [ 24 , 25 , 26 , 46 , 47 , 48 , 49 ]. Consequently, in the present study, the electron excitation and charge transport properties of DCVT-BTT as the monomer as a π-stacked dimer were calculated since the stacking interaction properties of DCV-BTT provide worthy information compared to the single molecule.…”

Photoluminescent Thin Films of Room-Temperature Glassy Tris(keto-hydrozone) Discotic Liquid Crystals and Their Nanocomposites with Single-Walled Carbon Nanotubes for Optoelectronics

“…Star-shaped DLCs having a disk-like core with three branches , have demonstrated very interesting electronic and luminescent response useful for diverse applications . By doping of such materials with CNTs, one can produce highly conductive DLC NCs that exhibit enhanced properties, e.g., improved light emissive and sensing characteristics.…”