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The branched structures of dendronized polymers can provide good steric stabilization for metal nanoparticle catalysts. In this work, an amphiphilic dendronized copolymer containing hydrophilic branched triethylene glycol moieties and hydrophobic branched ferrocenyl moieties is designed and prepared by one-pot ring-opening metathesis polymerization, and is used as the stabilizer for metal (Au, Ag and Pd) nanoparticles. These metal nanoparticles (Au nanoparticles: 3.5 ± 3.0 nm; Ag nanoparticles: 7.2 ± 4.0 nm; Pd nanoparticles: 2.5 ± 1.0 nm) are found to be highly active in both the 4-nitrophenol reduction and Suzuki–Miyaura reactions. In the 4-nitrophenol reduction, Pd nanoparticles have the highest catalytic ability (TOF: 2060 h−1). In addition, Pd nanoparticles are also an efficient catalyst for Suzuki–Miyaura reactions (TOF: 1980 h−1) and possess good applicability for diverse substrates. The amphiphilic dendronized copolymer will open a new door for the development of efficient metal nanoparticle catalysts. [ABSTRACT FROM AUTHOR]

Tannic acid is used as a green and efficient stabilizer to fabricate all kinds of TMNPs including AuNPs, AgNPs, CuNPs and PdNPs. These TMNPs possess small sizes ranging from 1 nm to 6 nm, which is conducive to several catalytic reactions in aqueous solution, such as 4-nitrophenol (4-NP) reduction, CuAAC reactions and Suzuki–Miyaura coupling reactions. This present work has the superiorities of green raw material, simple and efficient preparation process, high catalytic activities, as well as the applicability and generality for various substrates. [Display omitted] Due to the good electrical, optical, magnetic, catalytic properties, transition metal nanoparticles (TMNPs) have been becoming more and more interesting in the fileds of environment, material, biomedicine, catalysis, and so on. Here, tannic acid (TA) is used as a green and efficient stabilizer to fabricate all kinds of TMNPs including AuNPs, AgNPs, CuNPs and PdNPs. These TMNPs possess small sizes ranging from 1 nm to 6 nm, which is conducive to several catalytic reactions in aqueous solution, such as 4-nitrophenol (4-NP) reduction, CuAAC reactions and Suzuki–Miyaura coupling reactions. AuNPs and PdNPs are found to have distinctly higher catalytic activities than AgNPs and CuNPs in the 4-NP reduction process. Especially, PdNPs show the highest catalytic activities with TOF up to 7200 h−1 in the 4-NP reduction. Furthermore, PdNPs also exhibit satisfying catalytic performance in the Suzuki–Miyaura coupling process, and CuNPs are catalytically active in the copper-catalyzed azide alkyne cycloaddition (CuAAC) reactions. The applicability and generality of PdNPs and CuNPs are respectively confirmed via the reaction between different substrates in the Suzuki–Miyaura coupling reactions and the CuAAC reactions. This work present a simple, fast, green and efficient strategy to synthesize TMNPs for multiple catalysis. [ABSTRACT FROM AUTHOR]

Dendrimers with symmetrical 3D structures can be designed with various interior or exterior functional groups, which has been regarded as good stabilizers for various metal nanoparticles in catalysis. Nevertheless, Janus dendrimers with asymmetric structures are hardly researched to load metal nanoparticle catalysts. Here, an amphiphilic Janus dendrimer is used to stabilize metal (Au, Ag and Pd) nanoparticles, whose catalytic activities are also investigated. Au, Ag and Pd nanoparticles have the average diameters of 2.6 ± 2.0 nm, 5.8 ± 3.0 nm and 2.0 ± 1.0 nm, respectively, and show clear lattice fringes. Au and Pd nanoparticles are observed to have significantly higher catalytic performance than that of Ag nanoparticles in the 4-nitrophenol reduction, and Pd nanoparticles possess the highest catalytic activity (TOF: 2250 h−1). In addition, Pd nanoparticles are also highly active in the Suzuki-Miyaura reactions with low catalyst loading (50 ppm) and high TOF (2475 h−1) and show good applicability to tolerate various substituents. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract A series of small-sized (about 2.0 nm) gold nanoparticles (AuNPs) with apparent lattice fringes are synthesized by NaBH 4 reduction of HAuCl 4 in the presence of stabilizing linear or dendronized 1,2,3-triazolyl-containing ferrocenyl polymers. These AuNPs show high catalytic activity for biphasic 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) by NaBH 4. The lower generation G1 dendronized polymers (DPs) is a more efficient stabilizer for AuNP catalytic activity in the reduction of 4-NP than linear G0 polymers or bulky G2 DPs. The G1 DP-stabilized AuNPs are robust and easily recyclable, and the catalyst is recovered and reused at least twenty times with progressive smooth AuNP size increase along with some decrease of catalytic activity. [ABSTRACT FROM AUTHOR]

Biopolymer-derived hydrogels with low-cost and sustainable features have been considered as fascinating supported materials for metal nanoparticles. Cellulose, as the most abundant biopolymer, is a renewable raw material to prepare biopolymer-derived hydrogels for catalysis. Here, a cellulose-based hydrogel is designed to load bimetallic (AuAg, AuPd and AgPd) nanoparticles. 4-Nitrophenol reduction and Suzuki–Miyaura coupling reactions are selected to evaluate and compare the catalytic performance of the resulting bimetallic nanoparticle-loaded cellulose-based composite hydrogels. The bimetallic nanocomposite hydrogels are easy to be recycled over 10 times during the catalytic experiments and possess good applicability and generality for various substrates. The catalytic activity of bimetallic nanocomposite hydrogels was compared with recent literatures. In addition, the possible catalytic mechanism is also proposed. This work is expected to give a new insight for designing and preparing bimetallic nanoparticle-based cellulose hydrogels and proves its applicability and prospect in the catalytic field. [Display omitted] [ABSTRACT FROM AUTHOR]