Invited feature articlePyrene based chalcone materials as solid state luminogens with aggregation-induced enhanced emission properties

- Chalcone materials have been designed based on donor of pyrene linked to acceptor of heterocyclics via an ethylene bridge.
- The derivatives are categorized as green-light emission in solution while yellow light emission in solid state.
- AIEE of chalcones prevents π-π stacking and Restriction of Intramolecular Rotation impels that intense green-orange light in aggregated state.
- The bandgap energies were calculated from UV-visible, CV and DFT, the obtained values are similar and fall in semiconducting nature.

New series of pyrene based chalcone materials were synthesized by Claisen-Schmidt condensation exhibits dual characteristics such as aggregation-induced enhanced emission (AIEE) in solution as well as solid state luminescence. The photo-physical properties such as solvent effect, quantum yield and lifetime of materials were studied. They were demonstrated aggregation induced enhanced emission (AIEE) with broad colour changes from green to orange emission on different water fraction in THF/H2O mixture. The bulky group of pyrene attached to vinylene keto heterocyclic moiety disturbs the polarity of pyrene prevents π-π stacking and restriction of intramolecular rotation (RIR) in aggregated state is the possible cause for its emission enhancement. The significant unusual blue shift in aggregated state observed when water volume exceeds more than 80% in THF dependent on morphological changes from amorphous to crystalline state. The energy level of materials was derived from experimental as well as theoretical calculation. One of fascinating characteristics of chalcone is its low cost, trouble-free synthetic procedure, nontoxic and tuning emission properties. The obtained results are promising as organic luminescent as well as semiconducting materials.

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