Silica-supported Bi2O3[sbnd]Cr2O3 nanocomposite: Efficient catalyst for Pyrano[3,2-c]chromenes synthesis and DFT studies

Abstract

Synthesis of a new nanocomposite catalyst, consisting of Bi and Cr loaded on silica (Bi2O3Cr2O3@SiO2), is achieved using the incipient wetness impregnation approach. This catalyst is used to synthesize Dihydropyrano[3,2-c]chromene scaffold via one-pot reaction method involves the mixture of 4-Hydroxycoumarin, Malononitrile or Ethyl cyanoacetate and different aromatic aldehydes in methanol at room temperature. The catalyst was characterized using several methods such as XRD, FT-IR, FE-SEM, and EDS. The efficacy of this heterogeneous catalyst Bi2O3Cr2O3@SiO2 was evaluated by loading different wt% of bismuth and chromium on silica. The wt% of Bi2O3Cr2O3 (2.5–1) on SiO2 was proven to be extremely suitable catalytic activity to get high yield of products (up to 98 %) in short span of time (up to 15 min) with high selectivity as outlined in the proposed mechanism. Additionally, density functional theory (DFT) studies of the Dihydropyrano[3,2-c]chromenes were conducted to elucidate their electronic properties and reactivity. It provided insights into the frontier molecular orbitals, electrostatic potential maps of these synthesized compounds, offering valuable information for future rational design of related Chromene-based molecules. The catalyst was successfully recovered and reused for up to five reaction cycles without any significant decline in its catalytic efficiency. Future work will focus on expanding the use of this catalyst for synthesizing library of bioactive compounds.