Tunable Emission Properties of Indolizine-Based Aggregation-Induced Emission Luminogens for White-Light Emission

Unlike conventional
fluorophores experiencing aggregation-caused
quenching (ACQ) in the solid state, aggregation-induced emission (AIE)
luminogens (AIEgens) exhibit enhanced fluorescence upon aggregation.
This property renders AIEgens promising for various technological
applications. However, developing red-emitting AIEgens with high fluorescence
efficiency remains challenging due to structural constraints. Compact
red-light-emitting AIEgens hold great potential, as their small, simple
fluorescent frameworks enable facile modification and precise color
tuning. This study presents a novel compact indolizine-based AIE system
with solid-state emission tunable from cyan (496 nm) to deep red (669
nm), with an average molecular weight (MW) of 312.8 g/mol. The deep-red-emitting
derivative is uncommon among short-conjugation, low-molecular-weight
(∼280 g/mol) systems and demonstrates exceptional photophysical
characteristics. Through carbonyl functional groups, we modulated
molecular packing, resulting in distinct optical properties and emission
tunability in solid and aggregated states. Structural investigations
using single-crystal X-ray diffraction (SCXRD) and computational modeling
revealed that molecular packing and intermolecular interactions significantly
influence emission behavior. Integration of these AIEgens into blue-light-emitting
diode chips facilitated white-light production with CIE coordinates
(0.360, 0.362) and a color temperature of 4533 K. These findings underscore
the potential of indolizine-based AIEgens for next-generation emissive
materials, providing insights for their rational design and broader
technological applications.