Emission properties and application of multiaryl-substituted pyrroles

The luminogenic molecules are nonemissive when dissolved in good solvents but become highly luminescent when aggregated in the solid state, thus behaving exactly opposite to the conventional ACQ luminophores. Aggregation-induced emission (AIE) was coined for this unusual phenomenon. The relationship between the structures and light emission properties of multiaryl-substituted pyrrole derivatives was firstly studied in this review. On comparison of the optical properties and single-crystal structures of these pyrrole derivatives, it is suggested that the more twisted configuration which prevented parallel orientation of conjugated chromophores combined with the restricted intramolecular rotation (RIR) effect was the main cause of the AIE phenomenon. The carboxylated-functionalized derivatives can be used to sensitively, selectively and real-time detect Al³⁺ ion. The detection mechanism exhibited an aggregation-induced emission (AIE) characteristic. Triphenylpyrrole containing carboxylic acid (TPPA) was found to have a controllable fluorescence in the solid state when it is crystallized from dimethyl formamide (DMF). The rapid response, high selectivity, good reversibility and solvent-free procedure make TPPA a thermo-responsive material for use in temperature monitoring devices. Induced by DMF, Triphenylpyrrole acid (TPPA) derivatives can recrystallizate with good selectivity of temperature, quick response, and can be recycled.