Microwave-assisted preparation of graphene quantum dots immobilized nanosilica as an efficient heterogeneous nanocatalyst for the synthesis of xanthenes

Graphene quantum dots (GQDs) immobilized nanosilica was prepared under microwave irradiated green reaction conditions and was used as an efficient heterogeneous acid catalyst. The structure of nano-catalyst was characterized by FT-IR, PL, TEM, XRD, FE-SEM, EDS, TGA, and zeta potential. Xanthene derivatives were synthesized in excellent yields using the freshly prepared catalyst and the catalyst could be easily recovered and recycled for 5 times without significant loss of its catalytic activity. The structures of the resulted products were confirmed by FT-IR, H-1-NMR, C-13-NMR spectroscopic techniques.