Graphitic Carbon Nitride Nanosheets Covalently Functionalized with Biocompatible Vitamin B: Synthesis, Characterization, and Its Superior Performance for Synthesis of Quinoxalines.

The physical properties of two-dimensional nanosheet materials make them promising candidates as active materials in the areas of photoelectronics, fuel cells, sensors, water splitting, solar energy conversion, CO reduction, and heterogeneous catalysis. Among two-dimensional nanosheet materials, graphitic carbon nitride due to its electronic structure and high chemical and thermal stability possesses unique properties. Covalent functionalization of graphitic carbon nitride could be the key step in modifying its ability and significantly improving its properties. To this purpose, a novel strategy for the covalent functionalization of g-CN nanosheets (CN) with vitamin B (VB) by using 1,3-dibromopropane as a covalent linker for the first time is demonstrated. The obtained CN-Pr-VB exhibits increased thermal stability compared to the VB which is important in the practice application and can be easily dispersed in common organic solvents. The efficacy of the CN-Pr-VB as a heterogeneous organocatalyst was evaluated in the quinoxaline synthesis under solvent-free conditions and afforded good isolated yield with high purity. Moreover, the prepared catalyst could be facilely recycled and reused for seven consecutive cycles without a noticeable decrease in the catalytic activity. Extensive characterization confirmed the stability of morphology and chemical structure after recyclability of the CN-Pr-VB.