Synthesis of gem-tetraphenylethylene oligomers utilizing Suzuki reaction and their aggregation properties

• We have designed and synthesized four new gem-tetraphenylethylene-based oligomers utilizing Suzuki coupling reaction.
• Oligomers exhibit aggregation-induced emission enhancement property.
• They have good thermal stability.
• Substitution at the geminal position slightly induces the donating ability (HOMO) of oligomers.

Four new gem-tetraphenylethylene-based oligomers were synthesized by Suzuki coupling reaction in good yields (62–80%) and characterized by NMR, mass spectrometer and elemental analysis. The absorption maxima of the synthesized oligomers in the solution possess similar absorption bands located at 328–332 nm. They are shown to be thermally stable and emit light in blue region (404–485 nm). All the oligomers are AIE-active, emit weakly in solutions with Φf values not exceeding 4%, become strong emitters in the aggregated states and the PL intensity values increase up to 18-fold. The results of CV measurements of the oligomers showed good reversibility, indicating that the compounds have good electrochemical stability. The HOMO values of the oligomers are in the range of −5.63 to −5.61 eV. The photoluminescence properties in aggregate-state and the high HOMO energy levels of these oligomers make them applicable as an active material for a light-emitting device.

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