Two 2D Metal-Organic Frameworks Based on Purine Carboxylic Acid Ligands for Photocatalytic Oxidation of Sulfides and CO Chemical Fixation.

Two two-dimensional (2D) layered metal-organic frameworks (MOFs), namely, {[Yb()(HO)NO]·2HO} (Yb-MOF) and [Er()(HO)Cl] (Er-MOF) (H = 5-((6-purin-6-yl)amino)isophthalic acid), were constructed by a solvothermal method and characterized. The catalytic performance study showed that the Yb-MOF could efficiently catalyze the oxidation of sulfides to sulfoxides under 15 W light-emitting diode (LED) blue light irradiation. Electron paramagnetic resonance spectroscopy and free-radical trapping experiments demonstrated that the photocatalytic reaction process involved O, and the corresponding mechanism was proposed. Moreover, Er-MOF exhibited good catalytic efficiency and excellent substrate tolerance in the cycloaddition reaction of CO, and the reaction conditions were mild. After 5 cycles, the catalytic activities of two MOFs did not significantly decrease, and the framework structures remained unchanged. Therefore, the Yb-MOF and Er-MOF were considered efficient and stable heterogeneous catalysts.