Synthesis, characterization, crystal structure of magnesium compound based 3, 3′, 5, 5′-azobenzentetracarboxylic acid and application as high-performance heterogeneous catalyst for cyanosilylation

Half-Sandwich Ruthenium Complexes with Hydrazone Ligands: Preparation, Structure, and Catalytic Activity in Cyanosilylether Synthesis under an Air Atmosphere

A new class of N,O-coordinate half-sandwich ruthenium complexes supported by hydrazone ligands with a general formula of [Ru(η⁶-p-cymene)Cl(L)] have been obtained in moderate to excellent yields conveniently. These air- and moisture-stable ruthenium complexes exhibited excellent catalytic activity in cyanosilylether synthesis under mild reaction conditions. Under the catalysis of ruthenium, various cyanosilylethers with different substituents were obtained through a one-pot reaction of trimethylsilyl cyanide with carbonyl substrates, with good to excellent yields. Excellent catalytic efficiency, a wide substrate range, and mild reaction conditions made this type of ruthenium catalyst have potential for industrial application. All of the half-sandwich ruthenium complexes have been well described by infrared, nuclear magnetic resonance, and EA analysis. Molecular structures of ruthenium complexes 1 and 4 were confirmed by single-crystal X-ray analysis.

Copper-Based Metal–Organic Frameworks (MOFs) as an Emerging Catalytic Framework for Click Chemistry

In the extensive terrain of catalytic procedures for the synthesis of organic molecules, metal–organic frameworks (MOFs) as heterogenous catalysts have been investigated in a variety of chemical processes, including Friedel–Crafts reactions, condensation reactions, oxidations, and coupling reactions, and utilized owing to their specific properties such as high porosity, tuneability, extraordinary catalytic activity, and recyclability. The eminent copper-tailored MOF materials can be exceptionally dynamic and regioselective catalysts for click reactions (1,3-dipolar cycloaddition reaction). Considering the fact that Cu(I)-catalyzed alkyne–azide cycloaddition (CuAAC) reactions can be catalyzed by several other copper catalysts such as Cu (II)-β-cyclodextrin, Cu(OAc)2, Fe3O4@SiO2, picolinimidoamide–Cu(II) complex, and Cu(II) porphyrin graphene, the properties of sorption and reusability, as well as the high density of copper-MOFs, open an efficient and robust pathway for regimented catalysis of this reaction. This review provides a comprehensive description and analysis of the relevant literature on the utilization of Cu-MOFs as catalysts for CuAAC ‘click’ reactions published in the past decade.

Metal-organic frameworks incorporating azobenzene-based ligands as a heterogeneous Lewis-acid catalyst for cyanosilylation of imines

In this work, two novel metal-organic frameworks (MOFs) were synthesized by the reaction of azobenzene-based ligands and Zn(NO3)2/CdCO3 under solvothermal conditions with the formula of {[Zn2(abtc)(azpy)(H2O)2]·4H2O} n (1) and {[Cd(abtc)0.5(azpy)0.5(H2O)]·3H2O} n (2) (H4abtc = 3,3',5,5'-azobenzene tetracarboxylic acid, azpy = 4,4'-azobipyridine). According to the single-crystal X-ray diffraction (SC-XRD) analysis, complexes 1 and 2 possessed quite similar structures except for the coordination modes of the central metal nodes attributed to the difference between the cationic radius of Zn(ii) and Cd(ii). The Zn(ii) cations in 1 adopted a distorted seesaw coordination geometry and the coordination between Zn(ii) and organic linkers gave two-dimensional (2D) coordination networks, while the Cd(ii) cations in 2 could also bind with the carboxylate groups from neighboring coordination networks to form a three-dimensional (3D) coordination framework. Furthermore, complexes 1 and 2 showed high catalytic activity as heterogeneous Lewis-acid catalysts towards the cyanosilylation of imines with satisfactory reusability under mild conditions and the similar catalytic performance of 1 and 2 could be attributed to the similarity in their structures. A prudent mechanism has been proposed as well to elucidate the role of complexes 1 and 2 in the catalytic process.

Cu(II)-Containing Metal-Organic Framework with 1D Hexagonal Channels for Cyanosilylation Reaction and Anticancer Activity on Osteosarcoma Cells

A novel metal-organic framework (MOF) has been produced via Cu(NO₃)₂·6H₂O reaction with 3-(1H-tetrazol-5-yl)pyridine (HL) in water, and its chemical formula is {[(Cu(L)₂(H₂O)₂](H₂O)₈) _n } (1). Due to its high density of coordinately unsaturated sites along with large one-dimensional (1D) hexagonal channels, the activated complex 1 (1a) was explored as the solvent-free heterogeneous catalyst for cyanosilylation under mind conditions. The inhibitory function of compound 1a against the survival rate of OS-732 osteosarcoma cells was evaluated via Cell Counting Kit-8 (CCK-8) detection kit. Furthermore, the Annexin V-FITC/PI detection kit and the active oxygen (ROS) detection kit was carried out to determine the cell apoptosis levels and the ROS accumulation in OS-732 osteosarcoma cells after treatment by compound 1a.

Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent

A novel URJC-3 material based on cobalt and 5,5'-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P4₃ 2₁ 2 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77-298 K) and pressures (1-170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without the plethora of available NHCs with tailor-made electronic and steric properties. While their suitability to act as strong ligands toward transition metals has led to numerous applications of NHC complexes in homogeneous catalysis, their strong σ-donating and adaptable π-accepting abilities have also contributed to an impressive vitalization of main group chemistry with the isolation and characterization of NHC adducts of almost any element. Formally, NHC coordination to Lewis acids affords a transfer of nucleophilicity from the carbene carbon atom to the attached exocyclic moiety, and low-valent and low-coordinate adducts of the p-block elements with available lone pairs and/or polarized carbon-element π-bonds are able to act themselves as Lewis basic donor ligands toward transition metals. Accordingly, the availability of a large number of novel NHC adducts has not only produced new varieties of already existing ligand classes but has also allowed establishment of numerous complexes with unusual and often unprecedented element-metal bonds. This review aims at summarizing this development comprehensively and covers the usage of N-heterocyclic carbene adducts of the p-block elements as ligands in transition metal chemistry.