Cyclometalated Ir–Zr Metal–Organic Frameworks as Recyclable Visible-Light Photocatalysts for Sulfide Oxidation into Sulfoxide in Water

Abstract

Aerobic photo-oxidation of sulfide into sulfoxide in water is of great interest in green chemistry. In this study, three highly stable Ir­(III)–Zr­(IV) metal–organic frameworks (Ir–Zr MOFs), namely Zr6–Irbpy (bpy is 2,2′-bipyridine), Zr6–IrbpyOMe (bpyOMe is 4,4′-dimethoxy-2,2′-bipyridine), and Zr6–Irphen (phen is 1,10-phenanthroline), are constructed by using [Ir­(pqc)2(L)2]Cl complexes (where pqc is 2-phenylquinoline-4-carboxylic acid and L is an ancillary ligand bpy, bpyOMe, or phen) as linkers and Zr6 cluster as nodes. The constructed Ir–Zr MOFs present high catalytic activity on aerobic photo-oxidation of sulfide into sulfoxide under visible light irradiation in water at room temperature. Moreover, the reaction is high chemoselectivity and functional group tolerance. The catalyst can be readily recycled and reused at least 10 times without loss of catalytic activity. Mechanism studies demonstrate that superoxide radical is the reactive oxygen species in the sulfoxidation, which is generated by electron transfer from the excited triplet photosensitizer 3[Ir–Zr-MOF]* to O2. The high activity of photocatalytic sulfoxidation in water may be attributed to the stabilization of the persulfoxide intermediate by hydrogen bond formation with water solvent, which accelerates the conversion of persulfoxide into sulfoxide and prevents further oxidation of sulfoxide into sulfone. This work provides a new strategy for the green synthesis of sulfoxides under ambient conditions.

Flow Electrosynthesis of Sulfoxides, Sulfones, and Sulfoximines without Supporting Electrolytes

“…13 C­{ 1 H} NMR (126 MHz, CDCl 3 ) δ 151.6, 133.1, 124.4, 117.8, 114.9, 44.0 ppm. The spectroscopic data agree with the literature …”

“…The spectroscopic data agree with the literature. 45 1-Methoxy-4-(methylsulfinyl)benzene (2g). Compound 2g was synthesized following GP1 using (4-methoxyphenyl)(methyl)sulfane (1g, 231 mg, 1.5 mmol) to give the product as a colorless oil.…”

Cu–citric acid metal–organic framework: Synthesis, characterization and catalytic application in Suzuki–Miyaura cross‐coupling reaction and oxidation of sulfides

“…After completion of the oxidation reaction, the catalyst was removed by simple filtration and copper amount was calculated in filtered solution by AAS which found to be 0.0000283 mmol ml À1 . As known, this very small amount of copper does not have a significant effect on the 3 ZrO-SB-APT@MCM-41 45 91 [43] 4 DSA@MNPs 300 98 [44] 5 Z r 6 -Irphen 360 98 [45] 6 Cu@Fe 3 O 4 45 97 [46] 7 Ce@Fe 3 O 4 40 95 [46] 8 Polyimide-P25 120 94 [47] 9…”

Z‐Scheme In2S3/NU‐1000 Heterojunction for Boosting Photo‐Oxidation of Sulfide into Sulfoxide under Ambient Conditions

“…More importantly, the meso‐ and micro channels of MOFs during the heterogeneous catalytic process can also enrich the substrate, shorten the transmission distance and increase the reaction rate, even possess exceptional chemo‐, size‐, shape‐, and enantioselectivity [28] . Numerous MOFs‐based heterojunction semiconductors‐such as Ir(III)‐Zr(IV) MOFs, [29] Sn IV ‐porphyrin‐based MOF, [30] C 60 @PCN‐222, [31] MoO(O 2 ) 2 @En/MIL‐100(Cr) [32] ‐were reported as superior catalysts for aerobic photo‐oxidation of sulfide into sulfoxide.…”