L-arginine modified graphene oxide: A novel heterogeneous catalyst for synthesis of benzo[b]pyrans and pyrano[3,2‑c]chromenes

Abstract

L-arginine modified graphene oxide (GO-Arg) was introduced as a new heterogeneous biocatalyst for synthesis of benzo[b]pyran and pyrano[3,2‑c]chromene derivatives. First GO was synthesized and then, Arg was covalently bonded on its surface. The new catalyst was analyzed using spectroscopic techniques such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS) and Raman. XRD analysis results showed that, Arg was located between the graphene oxide layers. Comparison of the bond intensity ratio of the D and G (ID/IG) in GO and GO-Arg confirmed the presence of Arg via covalent bond on the GO surface. XPS analysis also confirmed the successful modification through the presence of CN bonds in the structure. Moreover, changes in morphology of the samples were observed using SEM analyze, respectively. Evaluation of the performance of the catalyst in the synthesis of benzo[b]pyran and pyrano[3,2‑c]chromene derivatives showed presentable results. Using of amino acid as an available organocatalyst, its stabilization by a simple method on graphene oxide, reusing the catalyst up to 5 times, and introducing a highly pure product are positive points of this work.