Photoredox C(sp3)‐C(sp2) Cross‐Dehydrogenative Coupling of Xanthene with β‐keto moiety using MoS2 Quantum Dot (QD) Catalyst

Thiolated molybdenum diselenide quantum dots as a bifunctional catalyst towards the synthesis of benzimidazoles

Functionalized transition metal dichalcogenides (TMDs) have garnered significant attention over the past decade in various applications, but they have seldom been explored in catalytic transformations. Driven by the motivation to explore the scope of functionalized TMDs in catalysis, the one-pot synthesis of benzimidazoles was considered as the model reaction. Heterocyclic compounds such as benzimidazoles are categorised as pharmaceutically relevant structures and always demand the development of improvised synthetic strategies. In this regard, we have developed a synthetic method using lower dimension, catalytically active, thiol-functionalized MoSe2 quantum dots (QDs). Mechanistic investigations revealed the utility of surface functionalization in enhancing the stability and photocatalytic properties by inducing lattice distortion. The developed nanomaterial acts as a bifunctional system by serving as a photocatalyst to generate the imine and, as a Lewis acid to facilitate the cyclization. The protocol could be generalised for a diverse range of substrates, and further extended towards the generation of benzoxazole. Moreover, some of the synthesised derivatives were found to exhibit antibacterial properties against Staphylococcus aureus. Our method highlights the development of surface-modified functionalized lower-dimensional nanomaterials as sustainable and dynamic alternatives in photocatalysis to generate a 'library' of lead molecules using economical and benign protocols.

Semiconductor Quantum Dots Act as Photocatalysts for Carbon-Carbon Bond Formation: Selective Functionalization of Xanthene's 9H Position

The potential of CdSe, CdS, MoS2, and WS2 QDs as semiconductor photocatalysts for selective functionalization of the xanthene 9H position through carbon-carbon bond formation has been investigated. Our study reveals valuable insights into the energy-transfer and electron-transfer pathways involved in these reactions, as well as the radical polar crossover (RPC) and triplet-to-triplet energy transfer (TTEnT) processes. Notably, this approach offers a range of intriguing features, including visible-light-mediated processes, inexpensive catalytic systems, mild reaction conditions, broad substrate scope, unfunctionalized starting materials, and suitability for gram-scale synthesis. This study makes a significant contribution to the newly emerging field of QD-catalyzed reactions, paving the way for future explorations.