Photophysical Study and Biological Applications of Synthetic Chalcone-Based Fluorescent Dyes

A chalcone series (3a–f) with electron push–pull effect was synthesized via a one-pot Claisen–Schmidt reaction with a simple purification step. The compounds exhibited strong emission, peaking around 512–567 nm with mega-stokes shift (∆λ = 93–139 nm) in polar solvents (DMSO, MeOH, and PBS) and showed good photo-stability. Therefore, 3a–f were applied in cellular imaging. After 3 h of incubation, green fluorescence was clearly brighter in cancer cells (HepG2) compared to normal cells (HEK-293), suggesting preferential accumulation in cancer cells. Moreover, all compounds exhibited higher cytotoxicity within 24 h toward cancer cells (IC₅₀ values ranging from 45 to 100 μM) than normal cells (IC₅₀ value >100 μM). Furthermore, the antimicrobial properties of chalcones 3a–f were investigated. Interestingly, 3a–f exhibited antibacterial activities against Escherichia coli and Staphylococcus aureus, with minimum bactericidal concentrations (MBC) of 0.10–0.60 mg/mL (375–1000 µM), suggesting their potential antibacterial activity against both Gram-negative and Gram-positive bacteria. Thus, this series of chalcone-derived fluorescent dyes with facile synthesis shows great potential for the development of antibiotics and cancer cell staining agents.