From multifunctional catalysts to smart substrates: adsorption control for efficient light-driven one-pot benzimidazole synthesis over Pd/NH2–Ni–Fe-MOF

Abstract

Light-driven one-pot tandem/cascade reactions have attracted increasing interest due to their green process and atomic efficiency. In addition to active sites, the adsorption behavior of reaction substrates also plays a critical role on the catalytic process, but is always overlooked. Herein, we report that modulating the reaction substrates to regulate the adsorption behavior of intermediates can effectively facilitate one-pot multi-step reactions. O-Nitroaniline is strategically selected to replace the commonly used o-phenylenediamine for reaction with benzyl alcohol to synthesize benzimidazole in a one-pot process under visible-light irradiation. The use of o-nitroaniline effectively promotes the adsorption of the benzyl alcohol-derived aldehyde intermediate on the catalyst but weakens the adsorption of o-nitroaniline-derived o-phenylenediamine. Thus, the condensation between these two intermediates can proceed smoothly, alleviating the fatal polymerization side reaction of o-phenylenediamine, affording high efficiency in light-driven benzimidazole production. Departing from the conventional catalyst design, this work underscores an effective way to modulate the reaction substrates for accelerated one-pot synthesis, signifying an important contribution to the design of one-pot synthesis systems.