Synthesis of Sm‐TADDbBP@MCM‐41 as a Robust, Reusable, and Practical Nanocatalyst in the Homoselective [2 + 3] Cycloaddition Reaction

ABSTRACT Schiff‐base materials are known ligands for the coordination of metal ions and the synthesis of various stable and useful complexes. Therefore, herein, a novel Schiff‐base compound {2,2′‐((1E,11E)‐2,5,8,11‐tetra azadodeca‐1,11‐diene‐1,12‐diyl) bis (4‐bromophenol)} was introduced that formed from condensation of triethylenetetramine (TETA) and 5‐bromo‐2‐hydroxybenzaldehyde (5B2HB). This Schiff‐base ligand was labeled as TADDbBP. Besides, mesoporous MCM‐41 was synthesized using tetraethyl orthosilicate (TEOS), hydrolyzing cetyltrimethylammonium bromide (CTAB) and NaOH solution (2 M), followed by calcination at 550 °C, and further, the silanol sites on the MCM‐41's surface were modified by 3‐chloropropyltriethoxysilane (3Cl‐PTES), which modified MCM‐41 was labeled as 3‐Cl‐Pr@MCM‐41. In the next step, the synthesized TADDbBP (as Schiff‐base ligand) was grafted on 3‐Cl‐Pr@MCM‐41, which was labeled as TADDbBP@MCM‐41, and further, it was coordinated with samarium ions (which was labeled as Sm‐TADDbBP@MCM‐41 nanocatalyst) using Sm (CH 3 COO) 3 . This is the first report on the production of Sm‐TADDbBP@MCM‐41 nanocatalyst, this nanocatalyst was characterized by TEM, SEM, EDX, elemental mapping, BET method, ICP, XRD, and TGA techniques. In the final step, the catalytic performance of Sm‐TADDbBP@MCM‐41 nanocatalyst has been checked in the homo‐selective producing of tetrazoles through [2 + 3] cycloaddition of benzonitriles and sodium azide (NaN 3 ) in PEG‐400 as available, nontoxic, green, and safe solvent. This nanocatalyst provides excellent selectivity in the synthesis of tetrazoles. In addition, Sm‐TADDbBP@MCM‐41 nanocatalyst can be separated and recycled for several cycles without significant reactivation or metal leaching.