Metallacycle-cored luminescent ionic liquid crystals with trigonal symmetry

Herein, we report the preparation of a series of metallacycle-cored liquid crystals with hexagonal and trigonal symmetries based on the self-assembly of tri(ethyl glycol) (TEG)-functionalized diplatinum(ii) ligands and alkyl chain-appendant tetraphenylethylene (TPE) derivatives. Interestingly, with the increase of the density of the TEG units in the metallacycles, the phase separation between TEG and alkyl chains reduces the symmetry of the columnar phase from hexagonal p6mm to trigonal p3m1, which significantly enhances the aggregation of TPE units and thus increases the emission of the system, resulting in fluorescence quantum yield as high as 47.4% in the mesogenic phase. Moreover, the positive charges of the metallacycles endow these liquid crystals with good ionic conductivity at room temperature, making them potential candidates for optoelectronics.