Photoinduced Synthesis of Functionalized Vinyl Aryl Sulfides from Diphenylacetylene Derivatives: Photophysical Properties and Theoretical Insights

Diarylacetylene-derived compounds are distinguished by their extended π-conjugation and photophysical properties.¹ Vinyl systems, particularly those functionalized with sulfur, exhibit environment-sensitive fluorescence and potential applications in fluorescent sensors and optoelectronic materials.² In this work, a sustainable methodology was developed for the photoinduced synthesis of trisubstituted vinyl aryl sulfides under visible-light irradiation. After optimization, the best reaction conditions employed DMSO, a 2 h reaction time, and thiophenol, affording product 3a in 70% yield. The methodology was applied to different diarylacetylenes 1a-1d and p-substituted thiols 2a-2c, providing six derivatives in 50-70% yields. Derivatives 3a-3f exhibited blue-green emission (444-471 nm), larger Stokes shifts, and enhanced fluorescence quantum yields compared with precursors 1a-1d, with derivative 3c showing the highest emissive efficiency. Frontier molecular orbital analysis indicated that the π-conjugated chromophore governs the photophysical properties, while the substituents promote subtle electronic modulation.