Imidazolium-based phosphinite ionic liquid (IL-OPPh2) as Pd ligand and solvent for selective dehalogenation or homocoupling of aryl halides

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Recent Advances in Processing and Applications of Heterobimetallic Oxide Thin Films by Aerosol-assisted Chemical Vapor Deposition

The fabrication of smart, efficient, and innovative devices critically needs highly refined thin-film nanomaterials; therefore, facile, scalable, and economical methods of thin films production are highly sought-after for the sustainable growth of the hi-tech industry. The chemical vapor deposition (CVD) technique is widely implemented at the industrial level due to its versatile features. However, common issues with a precursor, such as reduced volatility and thermal stability, restrict the use of CVD to produce novel and unique materials. A modified CVD approach, named aerosol-assisted CVD (AACVD), has been the center of attention due to its remarkable tendency to fabricate uniform, homogenous, and distinct nano-architecture thin films in an uncomplicated and straightforward manner. Above all, AACVD can utilize any custom-made or commercially available precursors, which can be transformed into a transparent solution in a common organic solvent; thus, a vast array of compounds can be used for the formation of nanomaterial thin films. This review article highlights the importance of AACVD in fabricating heterobimetallic oxide thin films and their potential in making energy production (e. g., photoelectrochemical water splitting), energy storage (e. g., supercapacitors), and environmental protection (e. g., electrochemical sensors) devices. A heterobimetallic oxide system involves two metallic species either in a composite, solid solution, or metal-doped metal oxides. Moreover, the AACVD tunable parameters, such as temperature, deposition time, and precursor, which drastically affect thin films microstructure and their performance in device applications, are also discussed. Lastly, the key challenges and issues of scaling up AACVD to the industrial level and processing for emerging functional materials are also highlighted.

WEPA: a bio-derived medium for added base, π-acid and ligand free Ullmann coupling of aryl halides using Pd(OAc)2

A bio-derived sustainable medium based on water extract of pomegranate ash (WEPA) has, for the first time, been developed for the homocoupling of aryl halides under palladium-assistance. Avoiding the requirement of an external base, ligand and π-acid, the use of the proposed renewable medium offers remarkable attributes like wide substrate scope, good to nearly quantitative yields of biphenyls with exceptional chemoselectivity and scale up viability.

Phosphinite-functionalized silica and hexagonal mesoporous silica containing palladium nanoparticles in Heck coupling reaction: synthesis, characterization, and catalytic activity

The preparation of phosphinite-functionalized silica and hexagonal mesoporous silica containing palladium nanoparticles is described. These catalysts were explored as heterogeneous catalytic systems in HCR with different substrates.

Microwave assisted Suzuki-Miyaura and Ullmann type homocoupling reactions of 2- and 3-halopyridines using a Pd(OAc)2/benzimidazolium salt and base catalyst system

A number of novel benzimidazole derivatives 1-4 were synthesized and the catalytic activity of these compounds in a catalytic system consisting of a benzimidazolium salt/Pd(OAc)2/K2CO3 were investigated in the Suzuki-Miyaura and Ullmann type homocoupling reactions under microwave irradiation. We obtained both cross coupling and homocoupling products of pyridine and some side products such as dimethylaminopyridine and unsubstituted pyridine.

Copper- and amine-free Sonogashira–Hagihara coupling reaction catalyzed by Pd(0) nanoparticles supported on modified crosslinked polyacrylamide

Pd(0) nanoparticles supported on modified crosslinked polyacrylamide containing phosphinite ligand was prepared. The complex was a highly efficient catalyst for the Sonogashira– Hagihara coupling reaction in the absence of a copper cocatalyst and an amine base under aerobic condition. This protocol can be applied for different aryl halides including chloroarenes. The catalyst can be reused several times without any considerable decrease in its activity because of low leaching of palladium metal from the support. Transmission electron microscopy (TEM) analysis of the catalyst revealed the formation of stable and polydispersed Pd(0) nanoparticles.

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki-Miyaura reactions

A diphenylphosphinite cellulose palladium complex (Cell–OPPh₂–Pd⁰) was found to be a highly efficient heterogeneous catalyst for the Suzuki–Miyaura reaction. The products were obtained in good to excellent yield under mild reaction conditions. Moreover, the catalyst could be easily recovered by simple filtration and reused for at least 6 cycles without losing its activity.