Palladium-Catalyzed Carbo-Oxygenative Cyclization of Chloroprenes to Access Organo-fluorophores

Owing to the high sensitivity and extensive applicability, fluorescence phenomena have emerged as essential research tools across various modern scientific disciplines and their interdisciplinary interfaces. Numerous strategies have been pursued to enhance the understanding, design, and manipulation of the photophysical properties of organic fluorophores while exploring their potential applications. However, existing fluorophores continue to encounter certain pitfalls that hinder their effectiveness. In advancing research within this field, we present a streamlined two-step protocol for the synthesis of an organo-fluorophore library using palladium-catalyzed carbo-oxygenative cyclization as the key transformative step. Mechanistic studies, featuring H2O18 labeling and DFT analysis, support the palladium-catalyzed carbo-oxygenative cyclization of chloroprene derivatives to forge these fluorophores with gram-scale synthesis as well. Notably, photophysical investigations indicate that constructed fluorophores absorb light in the visible range despite their small sizes (<400 g/mol), and a few of them show spectacular photoluminescence capabilities (ϕ) and fluorescence lifetime. Moreover, these fluorophores have demonstrated significant redox potential, which has been leveraged to illustrate their photocatalytic efficiency as photocatalysts. Furthermore, cell viability investigations revealed their low toxicity, exhibiting a remarkable selectivity for lysosomes, positioning them as a promising candidate for green lysotracker imaging agents.