Innovative Mn2Sb2O7 Nanocatalysts: Effective Generation of 2-Amino-4H-Chromenes Through Strategic Metal Doping

Abstract

This study focuses on the synthesis and characterization of Mn₂Sb₂O₇ and MnSb₂O₆ nanocatalysts, which were analyzed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy with energy dispersive X-ray (SEM-EDS), and transmission electron microscopy (TEM). The results confirm that the catalysts have similar chemical compositions and structures, with small amounts of vanadium (V) or iron (Fe) dopants evenly distributed throughout the material. These nanocatalysts demonstrated high efficiency in the one-pot synthesis of 2-amino-4H-chromenes from malononitrile, dimedone, and aryl aldehydes, achieving yields of 66–90% under optimal conditions using 10 mg of catalyst in ethanol at room temperature. Due to their amphoteric nature, the catalysts enable reactions via acid-mediated or base-mediated Hann-Lapworth mechanisms. Under optimal conditions, the catalysts exhibited turnover numbers (TON) ranging from 1.8 to 3.6 and turnover frequencies (TOF) between 0.0005 and 0.0009 s⁻¹. Moreover, the catalysts can be recovered and reused without losing activity, making them valuable for sustainable chemical synthesis applications.