A carbon quantum dot-encapsulated micellar reactor for the synthesis of chromene derivatives in water

Carbonized Polymer Dots-Promoted Photocatalytic Activation of Molecular Oxygen for Efficient and Selective Oxidation of Thioethers to Sulfoxides

Sulfoxides are essential in pharmaceuticals and chemicals, yet traditional thioether oxidation struggles with selectivity and sustainability. This study introduces carbonized polymer dots (CPDs) as effective photocatalysts for ecofriendly thioether to sulfoxide oxidation, using water and ethanol to enhance reaction selectivity and efficiency under 455 nm blue light. These catalysts not only show remarkable efficacy under mild conditions but also display high selectivity for sulfoxide formation, proving versatile across a broad range of substrates. We further elucidated the catalytic mechanism, confirming the predominant roles of singlet oxygen and superoxide anions through both spectroscopic evidence and quenching experiments. The method extends to the synthesis of pharmaceuticals such as oxfendazole, albendazole sulfoxide, and sulindac, highlighting its practical utility. Overall, our findings present a sustainable and efficient avenue for sulfoxide synthesis, thereby broadening the practical utility of CPDs in photocatalytic transformations.

Photo-activated Carbon dots (CDs) as Catalysts in the Knoevenagel Condensation: A Mechanistic Study by Dual-Mode Monitoring via ESI-MS

Carbon dots (CDs) obtained from 5-(hydroxymethyl)furfural (5-HMF) were activated by a 365 nm-UV irradiation source and employed in the Knoevenagel condensation to investigate their photocatalytic mechanism. To this end, electrospray ionization mass spectrometry (ESI-MS) was used to monitor the time progress of the condensation and follow the formation of the final product in positive and negative ion modes at once. The intervention of the superoxide radical anion in the photocatalytic mechanism of CDs was highlighted.

Sustainable synthesis of biomass-derived carbon quantum dots and their catalytic application for the assessment of α,β-unsaturated compounds

Herein, we demonstrate a simple, reproducible, and environment-friendly strategy for the synthesis of carbon quantum dots (CQDs) utilizing the mango (Mangifera indica) kernel as a renewable green carbon source. Various analytical tools characterized the as-prepared CQDs. These fluorescent CQDs showed significant water solubility with a uniform size of about 6 nm. The as-synthesized CQDs show significantly enhanced catalytic activity for the production of α,β-unsaturated compounds from the derivatives of aromatic alkynes and aldehydes under microwave irradiation in aqueous media. A potential mechanistic pathway and role of carboxylic functionalities were also revealed via various control experiments. The protocol shows outstanding selectivity towards the assessment of α,β-unsaturated compounds over other possible products. A comparative evaluation suggested the as-synthesized CQDs show higher catalytic activity under microwave radiation as compared to the conventional ways. These recyclable CQDs represent a sustainable alternative to metals in synthetic organic chemistry. A cleaner reaction profile, low catalyst loading, economic viability and recyclability of the catalyst, atom economy, and comprehensive substrate applicability are additional benefits of the current protocol according to green chemistry.

Carbocatalysis: a metal free green avenue towards carbon–carbon/heteroatom bond construction

Indeed, all the heterocycles comprises of either “C–C, C–N, C–S or C–O” bonds in their skeleton and construction of these bonds has laid the foundation stone of organic chemistry. The present researchers are continually attempting to develop new strategies for synthesizing miscellaneous structurally divergent molecular entities and these bond forming reactions are the fundamental tools. As a consequence, a colossal upheaval is witnessed in development of benign and sustainable synthetic routes for green bond-forming reactions envisaging carbon–carbon/heteroatom. This chapter is aimed towards highlighting the recent developments perceived in “C–C, C–N, C–S or C–O” bondconstruction especially emphasising greener perspectives i.e. carbocatalysis.