High density sulfonated magnetic carbon quantum dots as a photo enhanced, photo-induced proton generation, and photo switchable solid acid catalyst for room temperature one-pot reaction

Abstract

The preparation of photo enhanced and switchable (on/off mode) sulfonated magnetic carbon quantum dots was investigated in the present work. First, the as-synthesized carbon quantum dots (CQDs) were easily separated using a magnet (instead of using a dialysis method), then CQDs decorated with high density (9.6 mmol/g) acid groups (sulfonic + carboxylic) using chlorosulfonic acid. The photo-switchable activity of the catalyst related to the photoexitation of charge separation which in turn leads to electron withdrawing property in sulfonic groups. On the other hand, it was shown that sulfonated magnetic carbon quantum dot (S-M-CQDs) is more efficient than magnetic carbon quantum dot (M-CQDs). The as-prepared catalyst was characterized using SEM, TEM, EDX, XRD, IR, VSM and TGA. The catalytic activity of the as-prepared catalyst was evaluated at room temperature in one-pot reaction (synthesis of hexahydroquinoline derivatives). The as-synthesized catalyst easily retrieved using a magnet (than ultracentrifugation) and used in the next cycles.