Two Polymorphic Polyoxometalate-Based Metal–Organic Frameworks for the Efficient Synthesis of Functionalized Sulfoxides and Detoxification of Mustard Gas Simulants

Abstract

The development of high-efficient catalysts for the oxidation reaction of sulfides received much attention in recent years due to the extensive applications of such reactions from the utility in pharmaceutical chemistry and biology to the detoxification of chemical warfare agents in war. Herein, we report two innovative polyoxometalate-based metal−organic frameworks (POMOFs) {(1-α and 1-β), which were characterized by elemental analysis, UV−vis diffuse reflectance spectroscopy, X-ray single-crystal and powder diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy techniques in detail. Single-crystal X-ray diffraction analysis indicates that 1-α and 1-β are polymorphic with the identical compositions and analogical structures. Compounds 1-α and 1-β are both connected by Zn 4 -ε-Keggin polyoxoanions and 4,4′-bipyridine (bpy) ligands to form twofold interpenetrated three-dimensional POMOF structures. 1-β can be seen as a rotational polymorph of 1-α, that is, 1-α takes the b axis as the rotation axis and rotates ∼39°clockwise to obtain 1-β. Both compounds 1-α and 1-β can be used as heterogeneous catalysts to catalyze the selective oxidation of multitudinous sulfides with H 2 O 2 as an oxidant. When the oxidation of methyl phenyl sulfide was used as the template reaction, the yield of methyl phenyl sulfoxide is close to 100% within 30 min by 1-α and 1-β and the oxidant utilization efficiency is more than 93%. Gratifying catalytic effects have also been achieved in the selective oxidation of phenyl and aliphatic sulfide derivatives. Simultaneously, both 1-α and 1-β showed an extraordinary degradation efficiency of 2-chloroethyl ethyl sulfide and have a half lifetime (t 1/2 ) approximately 2.5 or 3 min, respectively, with 100% selectivity toward the nontoxic product 2-chloroethyl ethyl sulfoxide and an abnormally high oxidant utilization efficiency (94.5% for 1-α and 94.3% for 1-β) at room temperature. In addition, after seven cycles and continuous cycle catalytic experiments, their structures remained and catalytic activities did not decrease obviously, revealing their outstanding recyclability and structural stability.

Self-assembly of a novel multicomponent polyoxometalate-based tetrahedral supercluster with high catalytic activity for thioether oxidation

“…POMs are versatile for application in the domain of organic catalysis, due to the high surface electronegative properties and the activity to redox reactions. 31,32 Sulfones and sulfoxides play important roles in chemical industrial production as key synthetic intermediates, so the catalytic oxidation of thioethers, especially with POM-based complexes as catalysts has been growing interest. [33][34][35] Herein, the oxidation of methyl phenyl sulfide (MPS) was selected as a model reaction for the evaluation of catalytic oxidation ability (Scheme 1).…”

Smart Covalent Organic Framework with Proton-Initiated Switchable Photocatalytic Aerobic Oxidation

“…Photocatalytic oxidation of sulfides to sulfoxides (Figure a) is an important chemical reaction, which has wide applications in the selective synthesis of sulfoxide intermediates with pharmaceutical and chemical activities and the removal of toxic chemicals, such as oxidative desulfurization of petroleum and oxidative detoxification of sulfur mustard gas. − This model reaction was selected to evaluate the photocatalytic activity of HP-1 and HP-7. As shown in Figure b, HP-1 shows the best photocatalytic activity for the reaction (Figure S15).…”

An excellent multifunctional photocatalyst with a polyoxometalate–viologen framework for CEES oxidation, Cr(vi) reduction and dye decolorization under different light regimes

“…With the development of industry and economic growth, environmental pollution caused by chemical pollutants has aroused widespread concern all over the world. [1][2][3][4][5][6] Mustard gas (HD), as an easy and cheaply produced vesicant chemical warfare agent, can cause grievous skin blisters, irritation to the respiration system and eyes, etc. 7,8 , and it was used in World War I and recent terrorist attacks.…”