Enhanced Co-Adsorption of Alcohols and Amines for Visible Light Driven Oxidative Condensation Using Iron-Based MOF.

ABSTRACT

Imines are essential intermediates in organic transformations, and is generally produced by dehydrogenative condensation of alcohols and amines with the assist of specialized catalysts and additives. Heterogeneous photocatalysis provides a sustainable platform for such process without the using of toxic oxidants, yet a functionalized photocatalyst with optimized co-adsorption of reactants needs to be developed to promote the stoichiometric oxidative condensation under ambient conditions. Here, we show that benzyl alcohol and aniline adsorb non-interferingly on the Fe node and the linker sites of the MIL-53(Fe) metal organic frameworks (MOFs), respectively. The co-adsorption of both reactants barely influences the reduction of molecular oxygen to generate oxygen radicals, resulting in efficient formation of benzaldehyde under visible light. Additionally, the weak adsorption of water together with surface acidity of the MIL-53(Fe) promote a rapid condensation of benzaldehyde with aniline and the depletion of generated water, achieving an efficient C-N bond creation for a wide range of substrates.