Ruthenium(II)-cored supramolecular organic framework-mediated recyclable visible light photoreduction of azides to amines and cascade formation of lactams

Visible-light-driven cascade radical cyclization toward the synthesis of α-carbonyl alkyl-substituted benzimidazo[2,1-a]isoquinolin-6(5H)-one derivatives

A visible-light-driven cascade radical cyclization process of N-methacryloyl-2-phenylbenzimidazole has been established with α-carbonyl alkyl bromide. This protocol provides an efficient and practical method for the synthesis of various α-carbonyl alkyl-substituted benzimidazo[2,1-α]isoquinolin-6(5H)-ones in outstanding yields, mild reaction conditions and excellent functional group tolerance.

A visible-light-driven radical cyclization method has been developed for synthesis of α-carbonyl alkyl-substituted benzimidazo[2,1-a]isoquinolin-6(5H)-ones. This reaction is characterized by excellent yields and good functional group tolerance.

Autocatalytic deoximation reactions driven by visible light

Photocatalytic deoximation reaction was found to be an autocatalytic process that occurs via free-radical mechanism. Understanding the mechanism may help chemical engineers to develop related techniques to avoid the decomposition of oximes.

Heterogeneous photocatalysis of azides: extending nitrene photochemistry to longer wavelengths

The photodecomposition of azides to generate nitrenes usually requires wavelengths in the <300 nm region. In this study, we show that this reaction can be readily performed in the UVA region (368 nm) when catalyzed by Pd-decorated TiO2. In aqueous medium the reaction leads to amines, with water acting as the H source; however, in non-protic and non-nucleophilic media, such as acetonitrile, nitrenes recombine to yield azo compounds, while azirine-mediated trapping occurs in the presence of nucleophiles. The heterogeneous process facilitates catalyst separation while showing great chemoselectivity and high yields.

A Woven Supramolecular Metal-Organic Framework Comprising a Ruthenium Bis(terpyridine) Complex and Cucurbit[8]uril: Enhanced Catalytic Activity toward Alcohol Oxidation

The self-assembly of a diamondoid woven supramolecular metal-organic framework wSMOF-1 has been achieved from intertwined [Ru(tpy)₂ ]²⁺ (tpy=2,2',6',2''-terpyridine) complex M1 and cucurbit[8]uril (CB[8]) in water, where the intermolecular dimers formed by the appended aromatic arms of M1 are encapsulated in CB[8]. wSMOF-1 exhibits ordered pore periodicity in both water and the solid state, as confirmed by a combination of ¹ H NMR spectroscopy, UV-vis absorption, isothermal titration calorimetry, dynamic light scattering, small angle X-ray scattering and selected area electron diffraction experiments. The woven framework has a pore aperture of 2.1 nm, which allows for the free access of both secondary and primary alcohols and tert-butyl hydroperoxide (TBHP). Compared with the control molecule [Ru(tpy)₂ ]Cl₂ , the [Ru(tpy)₂ ]²⁺ unit of wSMOF-1 exhibits a remarkably higher heterogeneous catalysis activity for the oxidation of alcohols by TBHP in n-hexane. For the oxidation of 1-phenylethan-1-ol, the yield of acetophenone was increased from 10 % to 95 %.

Porous Ru(bpy)32+-Linked Polymers for Recyclable Photocatalysis of Enantioselective Alkylation of Aldehydes

Two metal porous organic polymers (POPs) that contain the [Ru(bpy)₃]²⁺ cores are prepared via one-pot Suzuki-Miyaura coupling reactions. Both Ru-POPs are thermally stable at up to 340 °C in air and do not dissolve in all solvents tested. One of the POPs has been revealed to be highly effective and reusable as a heterogeneous photocatalyst for visible light-driven enantioselective alkylation of aldehydes. After 10 cycles, the catalyst still maintains the enantioselectivity, while the activity just decreases slightly.

Water-Soluble 3D Covalent Organic Framework that Displays an Enhanced Enrichment Effect of Photosensitizers and Catalysts for the Reduction of Protons to H2

Covalent organic frameworks (COFs) are emerging porous polymers that have 2D or 3D long-range ordering. Currently available COFs are typically insoluble or decompose upon dissolution, which remarkably restricts their practical implementations. For 3D COFs, the achievement of noninterpenetration, which maximizes their porosity-derived applications, also remains a challenge synthetically. Here, we report the synthesis of the first highly water-soluble 3D COF (sCOF-101) from irreversible polymerization of a preorganized supramolecular organic framework through cucurbit[8]uril (CB[8])-controlled [2 + 2] photodimerization. Synchrotron X-ray scattering and diffraction analyses confirm that sCOF-101 exhibits porosity periodicity, with a channel diameter of 2.3 nm, in both water and the solid state and retains the periodicity under both strongly acidic and basic conditions. As an ordered 3D polymer, sCOF-101 can enrich [Ru(bpy)₃]²⁺ photosensitizers and redox-active polyoxometalates in water, which leads to remarkable increase of their photocatalytic activity for proton reduction to produce H₂.