Activation of Aryl Chlorides in Water under Phase-Transfer Agent-Free and Ligand-Free Suzuki Coupling by Heterogeneous Palladium Supported on Hybrid Mesoporous Carbon

Crystal phase-selective synthesis of intermetallic palladium borides and their phase-regulated (electro)catalytic properties

Three Pd–B intermetallics, namely, Pd6B, Pd5B2 and Pd2B, are synthesized, and their catalytic activities toward electrochemical water splitting and Suzuki coupling reactions are strongly associated with the Pd(d)–B(s,p) orbital hybridization.

Interfacial Assembly and Applications of Functional Mesoporous Materials

Functional mesoporous materials have gained tremendous attention due to their distinctive properties and potential applications. In recent decades, the self-assembly of micelles and framework precursors into mesostructures on the liquid-solid, liquid-liquid, and gas-liquid interface has been explored in the construction of functional mesoporous materials with diverse compositions, morphologies, mesostructures, and pore sizes. Compared with the one-phase solution synthetic approach, the introduction of a two-phase interface in the synthetic system changes self-assembly behaviors between micelles and framework species, leading to the possibility for the on-demand fabrication of unique mesoporous architectures. In addition, controlling the interfacial tension is critical to manipulate the self-assembly process for precise synthesis. In particular, recent breakthroughs based on the concept of the "monomicelles" assembly mechanism are very promising and interesting for the synthesis of functional mesoporous materials with the precise control. In this review, we highlight the synthetic strategies, principles, and interface engineering at the macroscale, microscale, and nanoscale for oriented interfacial assembly of functional mesoporous materials over the past 10 years. The potential applications in various fields, including adsorption, separation, sensors, catalysis, energy storage, solar cells, and biomedicine, are discussed. Finally, we also propose the remaining challenges, possible directions, and opportunities in this field for the future outlook.

Pd immobilization biguanidine modified Zr-UiO-66 MOF as a reusable heterogeneous catalyst in Suzuki-Miyaura coupling

In recent days, nanohybrid metal organic frameworks (MOF) have been considered as next generation catalysts due to their unique features like large surface to volume ratio, tailorable geometry, uniform pore sizes and homogeneous distribution of active sites. In this report, we address the biguanidine modified 3D Zr-centred MOF UiO-66-NH2 following a post synthetic modification approach. Utilizing the excellent chelating ability of biguanidine, Pd ions are immobilized over the host matrix MOF. The as-synthesized material was physicochemically characterized using a broad range of analytical techniques like FT-IR, electron microscopy, EDS, elemental mapping, XRD and ICP-OES. Subsequently the material has been catalytically employed in the classical Suzuki-Miyaura coupling towards the synthesis of diverse biphenyl derivatives at sustainable conditions. There are very few reports on the covalently modified MOFs towards the organic coupling reactions. The catalyst has been isolated by centrifugation and recycled in 9 consecutive runs with almost insignificant leaching and minute decrease in reactivity.

Magnetic chitosan stabilized palladium nanostructures: Potential catalysts for aqueous Suzuki coupling reactions

This work describes the preparation of palladium-based catalyst supported on magnetic chitosan (Pd@IO-Chitosan) for Suzuki Miyaura C-C coupling reaction. The Pd@IO-Chitosan catalyst was characterized using different spectroscopic and microscopic techniques such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), X-ray Absorption Near Edge Structure (XANES) Spectroscopy and X-ray photoelectron spectroscopy (XPS). Pd@IO-Chitosan was further analysed by thermogravimetric analysis (TGA) in order to determine its thermal behavior. The catalyst comprised Pd, PdO species stabilised by chitosan that facilitated Suzuki coupling reactions. Palladium loading as low as 0.0055 mol% was found to be effective for aqueous Suzuki cross-couplings with excellent yields of over 99%. The catalyst could be recycled and reused at least 12 times with no significant decrease in its catalytic activity.

Ultrasound assisted synthesis of Pd NPs decorated chitosan-starch functionalized Fe3O4 nanocomposite catalyst towards Suzuki-Miyaura coupling and reduction of 4-nitrophenol

In recent days the nanomagnetic biocomposites have been evolved as sustainable green catalysts. In that context, we are prompted to design and synthesize a novel Pd NP adorned chitosan-starch dual biopolymer encapsulated core-shell type magnetic nanocomposite (Fe₃O₄@CS-Starch/Pd) in an eco-friendly pathway applying ultrasound irradiations. The morphological and physicochemical features of the material were determined using several advanced techniques like FT-IR, FESEM, HRTEM, EDX, atomic mapping, VSM, XRD and ICP-OES. Catalytic efficiency of the material was investigated in the ultrasound assisted classical Suzuki-Miyaura coupling towards the synthesis of diverse range of biaryl derivatives and in the catalytic reduction of 4-Nitrophenol.In both the protocols the catalyst exhibited excellent performances. Sonication had a significant role in enhancing the catalytic performances in both the reactions as compared to conventional heating. Due to super-paramagnetism, the catalyst was easily magnetically isolable and reused in 11 cycles without considerable leaching and change in reactivity.

Phosphine-Built-in Porous Organic Cage for Stabilization and Boosting the Catalytic Performance of Palladium Nanoparticles in Cross-Coupling of Aryl Halides

Herein, we report first a novel phosphine-containing porous organic cage (PPOC) from a [2 + 3] self-assembly of triphenyl phosphine-based trialdehyde and (S,S)-1,2-diaminocyclohexane via dynamic imine chemistry, which was employed as a porous material for the controlled growth of palladium nanoparticles (NPs) due to the strong affinity of Pd to the phosphine ligand based on the principle of hard and soft acids and bases. Comprehensive characterizations including X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, NMR, and X-ray absorption spectroscopy reveal that ultrafine Pd NPs with narrow size distribution (1.7 ± 0.3 nm) and enhanced surface electronic density via a strong interaction between NPs and phosphine were homogeneously dispersed in the PPOC. The resultant catalyst Pd@PPOC exhibits remarkably superior catalytic activities for various cross-coupling reactions of aryl halides, for example, Sonogashira, Suzuki, Heck, and carbonylation. The catalytic activity of Pd@PPOC outperforms the state-of-the-art Pd complexes and other Pd NPs supported on N-containing porous cages under identical conditions, owing to the enhanced surface electronic density of Pd NPs and their high stability and dispersibility in solution. More importantly, Pd@PPOC is highly stable and easily recycled and reused without loss of their catalytic activity. This work provides a new functional POC with extended potentials in catalysis and material science.

Controlled Synthesis of Palladium Nanocubes as an Efficient Nanocatalyst for Suzuki-Miyaura Cross-Coupling and Reduction of p-Nitrophenol

Anisotropic nanocatalysts have attracted considerable attention in comparison to bulk/nanocatalysts for their enhanced activity and reactivity. The demand toward anisotropic palladium (Pd) nanostructures has increased rapidly in the field of catalysis. Pd is a well-known active catalyst for several carbon-carbon (C-C) cross-coupling reactions; among them, the Suzuki-Miyaura cross-coupling reaction is one of the most versatile and dominant methods for constructing the extraordinarily useful unsymmetrical biaryls and also for hydrogenation of organic contaminants like p-nitrophenol (p-NP). This paper provides a brief explanation about the controlled synthesis, characterization, and catalytic activity of well-defined palladium nanocubes (Pd NCs) prepared by a seed-mediated method. The synthesized monodispersed Pd NCs were characterized by spectroscopic and microscopic tools such as UV-visible, XRD, FESEM, HRTEM, and EDS analyses. Pd NCs proved as an efficient catalyst for Suzuki-Miyaura cross-coupling reactions and p-NP reduction. The catalyst shows enhanced activity, greater stability, and higher selectivity with remarkable recyclability up to 92% for five consecutive cycles. The catalytic performance of the synthesized Pd NCs was also studied in the reduction of the organic contaminant p-NP, which showed an excellent performance screening of 99% conversion in 6 min.

An Amino-Chain Modified β-cyclodextrin: A Supramolecular Ligand for Pd(OAc)2 Acceleration in Suzuki–Miyaura Coupling Reactions in Water

A well-designed and synthesized water-soluble class of β-cyclodextrin supported palladium complex PdLn@Et-β-CD could efficiently validate high catalytic activity and act as a supramolecular platform for phosphine-free Suzuki–Miyaura cross‐coupling reactions between arylboronic acid/ arylboronic ester and aryl halides in water under mild conditions. The presented novel PdLn@Pr-β-CD complex catalyst was characterized by NMR, XRD, FT-IR, and DSC analysis. Furthermore, the role of the PdLn@Et-β-CD fragment in the reaction mechanism studied by molecular complexation was proposed based on FT-IR, 2D NMR (ROESY) spectroscopy, FE-SEM, and DSC spectroscopic analysis. The important benefits of this technique comprise simple phosphine-free preparation of the palladium catalyst, a wide range of functional-group tolerance, and easy recyclability; this method, furthermore, eschews hazardous reagents or solvents.

Development of a Sulfur-Modified Glass-Supported Pd Nanoparticle Catalyst for Suzuki-Miyaura Coupling

A safe, facile and low-leaching (up to 0.17 ppm) sulfur-modified glass-supported palladium nanoparticle catalyst has been developed for the Suzuki-Miyaura coupling of aryl halides with aryl boronic acids. Most notably, this catalyst was highly recyclable and could be used up to 10 times without any discernible decrease in its activity.

POSS-based meso-/macroporous covalent networks: supporting and stabilizing Pd for Suzuki–Miyaura reaction at room temperature

Porous covalent organic networks synthesized by Schiff base chemistry reaction of POSS and terephthalic aldehyde could serve as both supports and stabilizers for Pd catalyst, which exhibited excellent performances for Suzuki-Miyaura reactions.

Preparing highly-dispersed noble metal supported mesoporous silica catalysts by reductive amphiphilic molecules

We present an in situ reduction strategy to prepare mesoporous silica supported by highly-dispersed noble metals.

Palladium supported on phosphinite functionalized Fe3O4 nanoparticles as a new magnetically separable catalyst for Suzuki–Miyaura coupling reactions in aqueous media

Novel phosphinite functionalized magnetic (Fe₃O₄) nanoparticles having silica nanoshells containing an imidazolium ionic liquid moiety have been successfully synthesized and used as a support and stabilizer for palladium nanoparticles.

A novel polymer containing phosphorus–nitrogen ligands for stabilization of palladium nanoparticles: an efficient and recyclable catalyst for Suzuki and Sonogashira reactions in neat water

Highly monodispersed palladium nanoparticles supported on polymer containing phosphorus and nitrogen ligands was successfully synthesized, characterized and used in Suzuki and Sonogashira coupling reactions in water.