Design, and Synthesis of Donor-π-Acceptor (D-π-A) Heterocyclic Compounds Exhibiting Aggregation-Induced Emission (AIE/AIEE) and Solid-State Emission.

Authors

Thangjam Linda Devi, Mayanglambam Maneeta Devi, Francis A S Chipem, Okram Mukherjee Singh

Published in

Journal of fluorescence. Jul 27, 2026. Epub Jul 27, 2026.

Abstract

A new donor-π-acceptor (D-π-A) fluorescent chromophore incorporating an indole-pyrazole donor framework and an electron-accepting unit, 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene)malononitrile (TCF) was designed. Various active-methylene compounds were also incorporated into the indole-pyrazole donor units to explore the substrate scope of the reaction. The molecular structure was confirmed by spectroscopic techniques, including NMR, FT-IR, and high-resolution mass spectrometry. Their photophysical properties were investigated using UV-Vis absorption and fluorescence spectroscopy in solution, aggregated media, and the solid state. The D-π-A system exhibited weak fluorescence in dilute solution but showed a pronounced aggregation-induced emission/enhancement (AIE/AIEE) effect upon increasing the water fraction in DMSO-water mixtures, accompanied by significantly enhanced fluorescence quantum yields and intense solid-state emission. The enhanced emission is attributed to restricted intramolecular motion in the aggregated state, while efficient intramolecular charge transfer arising from the donor-acceptor framework contributes to their fluorescence behavior. Density functional theory (DFT) calculations on Indole-Pyrazole Donor-Acceptor compounds (IPDA-1 to IPDA-5) further elucidated their electronic structures and supported the experimental photophysical observations. These combined experimental and theoretical results demonstrate that the indole-pyrazole-based D-π-A architecture is an effective molecular platform for developing aggregation-induced emissive luminogens with enhanced solid-state fluorescence and improved quantum yield in the aggregated state highlighting the potential of the synthesized D-π-A fluorophore as a promising candidate for future functional fluorescent materials.

PMID:
42507317
Bibliographic data and abstract were imported from PubMed on 27 Jul 2026.

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