Aluminum anchored on g-C3N4 as robust catalysts for Mannich reaction at ambient temperature

•A new reusable Al@C3N4 composite was fabricated by a simple method.•Developing a unique catalyst for synthesizing compounds with pharmaceutical values.•Taking place the reacting under mild condition and green media.•Nanocomposites are characterized by different analysis methods,•Scalable, versatile, and eco-friendly Mannich reactions in good to excellent yields.•The composite system was recycled several times without loss in its activity. Designing new heterogeneous catalysts from cheap and straightforward starting materials that enable benignly, mild organic transformations is now increasingly important both academy and industry. This study explores the simplistic ultrasonic-assisted synthesis of Al-doped g-C3N4 nanosheets (Al@g-C3N4) with the porous structure to prepare a metal-containing carbon nitride. The resulting nanocomposite was characterized using FTIR, EDX, and SEM spectroscopy and analyzed by morphological structure and chemical composition. The metal doping of AlCl3 on the surface of g-C3N4 leads to a unique nanocomposite structure, and the outcome is the production of a highly efficient catalyst for the Mannich reaction. The reactions are performed efficiently and with relatively high average efficiency in an optimal time and completed through a straightforward method. In addition, Al@g-C3N4 could be easily recycled, and no significant decrease was observed in its catalytic performance after five runs. [Display omitted]