Synthesis of Self-Assembled Molecules Based on Tetraphenylethene-Core Inducing Emission

Abstract

Aggregation-induced emission (AIE) organic materials have been extensively explored for a future sensible and interactive display to provide high luminescence in ordered states. However, it is challenging for reducing exciton quenching of aggregated materials to achieve high emission and increasing ordered structure to yield high crystallinity as well. To this end, the new structures based on tetraphenylene (TP) core were synthesized by attaching TP with clipping groups (C) consisting of a self-assembling group (SAG) to enhance emission intensity and spectra shift. As the emissive materials for self-assembly, TPCns with different clip numbers (n=1,2,4) were synthesized through the Wittig-Hörner reaction, where clips consist of extended π-conjugated moiety and the alkyl chain as a segment. The clips could introduce van der Waals interaction to facilitate self-assembly among clips and clip-connected aromatic units. These structures were confirmed and analyzed by different tools including 1 HNMR, 13 CNMR, FTIR-ATR, element analysis, MALDI-TOF/TOF. The optical properties of TPCns were discussed in solution state and solid state. In terms of photoluminescent emission, the TPC4 showed a more yellowish-green emission (λ em = 525nm in THF) and large aggregation-induced emission enhancement (EAIE) in aqueous (f w > 50%) THF solution. The greenish blue emission was realized for TPC1 at the maxima wavelength 481 nm and reached 100% quantum yield in the solid state. Furthermore, due to strong twisted intramolecular charge transfer, TPCn molecules had large Stokes shifts in ranges of 5800–6800 cm −1 for TPC1, TPC2, and 10700–12500 cm −1 for TPC4.