Synthesis and Photophysical Properties of Electroactive Apocynin Derivatives as Potential Luminogens and Cellular Bioimaging Agents

This study describes the synthesis, photophysical characterization, and bioimaging properties of a series of chalcones derived from apocynin, functionalized with electroactive groups such as phenyldimethylamine (1), triphenylamine (2), tetraphenylethylene (3), and pyrene (4). These molecules featured donor−π–acceptor–donor (D−π–A–D) type architectures designed to promote intramolecular charge transfer (ICT) processes and notable emissive properties. Compounds 1 and 2 exhibited a marked aggregation-caused quenching (ACQ) behavior in THF/water mixtures while compounds 3 and 4 showed a marked enhancement of emission upon aggregation (AIE), associated with the restriction of intramolecular motions in the aggregated state. DFT/TD-DFT calculations and electrochemical studies revealed good electronic communications between the electroactive units. Cellular bioimaging studies performed on compounds 1–4 showed that only compounds 1, 2, and 4 are good fluorescent agents exhibiting notable cellular permeability in HEp-2 carcinoma cells. Overall, these findings demonstrate that apocynin α,β-unsaturated systems constitute versatile luminescent platforms with tunable photophysical properties, suitable for applications in cellular bioimaging and the development of remarkable fluorescent materials.