Electron-modulating effects of intercalating molecules in functionalized graphene oxide: Optimizing the coordination microenvironment of Ag nanoparticles for efficient catalytic A3 coupling reactions

Abstract

In this paper, functionalized graphene oxide (GO) nanosheets were modified by forming benzamide (BzA) bonds using aniline with different substituents (4-tertbutylaniline, 4-nitroaniline, aniline) as intercalating molecules. Then the Ag@R-BzA/GO composite catalysts were prepared by loading Ag nanoparticles to reveal the electronic modulation of functionalized graphene oxide interfaces by aniline molecules effects with different substituents. The experimental results showed that the layer spacing of the composites obtained after intercalation with aniline whose substituent is an electron-giving group increased by about 40%. Moreover, the electron donating role of tert‑butyl regulates the charge distribution on the graphene oxide material and provides a good coordination environment for the loading of Ag nanoparticles. AgNPs are stably present in the interlayer of graphene oxide nanosheets by ligating with amide bonds and oxygen-containing functional groups to produce strong metal-carrier interactions. Ag@4‑tert-BzA/GO composites showed high catalytic activity in the A3 coupling reaction of aldehydes, alkynes and amines for the synthesis of alkynylamines(TON=19225.82). The electronic effect of the substituent groups on the intercalated molecules reported in this paper is a modulation on the molecular and atomic scale, which provides a new idea for the modulation of the microenvironment in metal-loaded catalysts.