Benzothiadiazole-based bolaamphiphiles: synthesis, self-assembly and white-light emissive properties

Novel benzothiadiazole-based bolaamphiphiles comprising a donor-acceptor-donor (thiophene-benzothiadiazole-thiophene) -conjugated rod, two diol groups at the terminals and two alkyl chains at the lateral positions can self-assemble into square honeycomb LC phases and helical gel structures in organic solvents. The square columnar phases should have 4 molecules in each unit cell and 2 molecules in each cell wall with the c-parameter (intermolecular distance) varying from compound to compound. The UV-vis spectra of these red emissive BTD-based bolaamphiphiles covered almost the whole visible range with a relatively low band gap. Most interestingly, white light with CIE coordinates (0.30, 0.33) was obtained by doping this BTD-based bolaamphiphile with a blue emissive dithiophene bolaamphiphile and yellow-green emissive tetrathiophene bolaamphiphile.