Citrus limetta peels derived carbon dots as highly active carbocatalyst for carbon–carbon bond formation.

The development of an eco-friendly, cost-effective and highly efficient bio-based catalyst is of great significance in organic transformations. Traditionally and currently used catalysts and solvents persist some limitations including high cost, toxicity, less stability, or eco-destructive. Herein, we report an eco-friendly green approach for synthesizing arylidene propanedinitrile (malononitrile) by using carbon dots as a novel precursor derived from waste peels of Citrus limetta. A series of arylidene propanedinitrile compounds were synthesized and subjected to in vitro antioxidant and antimicrobial activity. The compounds displayed a potent effect against clinical isolates of Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive). Furthermore, the antioxidant assays for these arylidene propanedinitrile derivatives were performed where 3b, 3c, 3e and 3i yielded the most promising results against DPPH and compound 3a, 3f, 3 h and 3j gave best results against ABTS free radical. These preliminary bioassay results clearly represent that these compounds have great potential in medical science. [ABSTRACT FROM AUTHOR]