Imidazo[1,2-a]pyridine-based donor-π-acceptor organic fluorophores with aggregation-induced emission and live-cell imaging studies.

Abstract

The rational design of organic fluorophores with tunable photophysical properties is of considerable interest for the development of advanced luminescent materials. In this work, we report the design, synthesis and characterization of two novel imidazo[1,2-a]pyridine-based donor-π-acceptor (D-π-A) fluorophores. In the molecular architecture, the imidazo[1,2-a]pyridine core acts as an electron-donating unit, and an electron-accepting group is attached through a conjugated π-bridge to construct efficient push-pull systems. Both probes, SSF-1 and SSF-2, showed solvent-dependent absorption shifts of 520-567 nm and 464-515 nm, respectively. A pronounced redshift in emission from 609 nm in dioxane to 728 nm in water was observed for SSF-1, with a significant increase in Stokes shift from 89 to 161 nm. For SSF-2, the emission shifted from 600 to 625 nm, with a Stokes shift of 157 nm in MeOH. Density Functional Theory (DFT) calculations further supported the experimental results and confirmed a smaller HOMO-LUMO energy gap for SSF-1 (ΔE = 2.56 eV) than for SSF-2 (ΔE = 2.71 eV). Both organic fluorophores, SSF-1 and SSF-2, showed solid-state emission maxima at 735 and 732 nm, respectively. In addition, both fluorophores exhibited low cytotoxicity and efficient cellular uptake, with intracellular fluorescence in COS-7, HeLa, and RPE1 cells. The combined experimental study highlights the potential of imidazo[1,2-a]pyridine-based fluorophores as promising candidates for advanced luminescent material applications.

Abstract as supplied by the indexing source. © the authors / publisher.