Size-Controlled Synthesis of Modifiable Glycine-Terminated Au Nanoclusters as a Platform for Further Functionalization

Alyari, Maryam; Scott, Robert W. J.

doi:10.1021/acs.langmuir.1c02225

Cited by 1 publication

(4 citation statements)

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“…One strategy used here is based on the synthesis of atom-precise Au NCs followed by building the dendritic architecture on the NC surface (multi-step reactions, divergent approach). Reactive atom-precise amine-terminated Au NCs with different core sizes (by controlling the concentration of the reducing agent) were first prepared by the Brust–Schiffrin method using a Fmoc-Gly-CSA capping agent, followed by deprotection of the Fmoc groups, as previously reported . The advantages/disadvantages of the divergent approach were thoroughly investigated in comparison to direct synthesis.…”

Section: Resultsmentioning

confidence: 99%

“…For the alternative divergent synthesis of Au cluster-cored dendrimers, the first reaction was the reaction of methyl acrylate with primary amine groups of Gly-CSA-functionalized Au NCs by a Michael addition reaction in a 2:1 ratio, which was previously reported (reaction i in Scheme ). This reaction produced MA-Gly-CSA-functionalized Au NCs (G0.5-COOMe-Au) with little to no change in the average core size according to UV–vis (panels a and b of Figure ) and TEM images (panels a and b of Figure ). G1.5-COOMe-Au NCs were synthesized in a stepwise manner by the reaction of G0.5-COOMe-Au with ethylenediamine to form G1.0-NH 2 -Au NCs, followed by a subsequent second Michael addition reaction with methyl acrylate (reactions ii and iii in Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…Gly-CSA-functionalized Au NCs with two different core sizes have been used in the synthesis of cluster-cored dendrimers using the divergent method: 1.2 ± 0.3 and 1.8 ± 0.3 nm. Gly-CSA-functionalized Au NCs were synthesized using synthetic methodologies outlined previously . Gly-CSA-functionalized Au NCs (5.0 mg) were dissolved in a 6 mL mixture of water/acetonitrile (1:1) followed by the addition of methyl acrylate (33.0 mmol, 3.0 mL).…”

Section: Methodsmentioning

confidence: 99%

“…Herein, we report the synthesis of Au cluster-cored dendrimers by both direct synthesis and post-functionalization (divergent) strategies to generate ester- and amine-terminated Au cluster-cored dendrimers with controlled core sizes and different dendron generations, as shown in Scheme . We have previously synthesized Fmoc-glycine-cystamine (Fmoc-Gly-CSA)-functionalized Au nanoclusters (NCs) and showed that the subsequent deprotection of the Fmoc group of the NCs allows for the synthesis of Gly-CSA-functionalized Au NCs, which have primary amine groups on their surfaces. , We have also recently shown that this strategy can allow for the fabrication of atom-precise Au 25 (Gly-CSA) 18 NCs, which can be further functionalized . Herein, multi-step reactions (Michael addition reactions followed by amide coupling reactions) are employed to build dendritic structures on the amine-functionalized NCs.…”

Section: Introductionmentioning

confidence: 99%

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Au Cluster-Cored Dendrimers Fabricated by Direct Synthesis and Post-functionalization Routes

Alyari

Scott

2022

Langmuir

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The use of dendrimers and dendrons as stabilizing agents for metal nanoparticles and nanoclusters has captured interest in both the biomedicine and catalysis fields. Herein, we describe the synthesis of Au cluster-cored dendrimers by either direct synthesis or multi-step functionalization pathways. Direct synthesis of Au cluster-cored dendrimers was performed by the Brust−Schiffrin method using cystamine core poly(amidoamine) (PAMAM) dendrons as capping agents. Alternatively, a divergent approach to make nanoclusters with dendritic branching groups by functionalizing glycine-cystamine Au clusters was also carried out. This synthesis involved sequential Michael addition reactions of methyl acrylate followed by a subsequent amide coupling reaction with ethylenediamine on amine-terminated Au nanoclusters to form dendritic architectures around the Au core. The chemical structure of the ligands was confirmed by proton nuclear magnetic resonance after each functionalization reaction, and the cluster size was characterized by transmission electron microscopy. Au cluster-cored dendrimers with amine or ester terminal groups on the surface were produced. The resulting amine-and ester-terminated Au cluster-cored dendrimers synthesized by the divergent method are stable in solution and in the presence of excess reducing agent. In contrast, amine-terminated Au cluster-cored dendrimers synthesized by direct synthesis undergo aggregation in solution over time as a result of the high reactivity of the surface, while ester-terminated Au cluster-cored dendrimers formed by direct synthesis have much larger core sizes than seen using the divergent approach. Finally, the catalytic activities of these clusters for 4-nitrophenol reductions have been investigated. Clustercored dendrimers formed by direct synthesis had larger core sizes and higher catalytic activities than those formed by the divergent approach, which is likely due to the poor passivation of the Au surface for the directly synthesized clusters. Furthermore, Au clustercored dendrimers with less sterically bulky dendrons showed higher catalytic activities.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%