Catalytic performance of g-C3N4 for pyrano [2, 3-d] pyrimidines formation: a combined experimental and DFT approach

Herein, we have developed a graphitic carbon nitride (g-C₃N₄) base catalyst via novel and environment-benign thermal method by treatment on melamine. The synthesized g-C₃N₄ base catalyst was characterized through various techniques including powder XRD, FTIR, TGA, SEM, EDX, UV–visible spectroscopy and BET analysis. The catalytic potency of g-C₃N₄ was evaluated in multicomponent reactions, particularly in Knoevenagel reactions for Pyrano [2, 3-d] pyrimidine formation. The result achieved in the current organic transformation demonstrates the high catalytic efficiency of g-C₃N₄ catalyst in Knoevenagel condensation. Moreover, the electron-donating and electron-withdrawing substituent effects on energy changes were investigated by quantum chemistry calculations including density functional theory (DFT studies). Additionally, DFT studies were also employed to study the optimized structure of the catalyst and derivatives, revealing key information on HOMO–LUMO energy levels, global reactivity descriptors, molecular electrostatic potential, contour analysis and DOS (Density of States) diagrams. The recyclability of g-C₃N₄ catalyst was analysed, confirming its sustainable use in multiple reaction cycles without significant loss of activity. These findings underline the significance of g-C₃N₄ as a versatile and recyclable catalyst in organic transformations, paving the way for future advancements in green and sustainable chemistry.

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