N-Heterocyclic carbene-ended polymers as surface ligands of plasmonic metal nanoparticles

Thanneeru, Srinivas; Ayers, Kaitlynn M.; Anuganti, Murali; Zhang, Lei; Kumar, Challa V.; Ung, Gaël; He, Jie

doi:10.1039/c9tc04776j

Cited by 26 publications

(26 citation statements)

References 68 publications

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“…They reported that the binding constant of the thiol polymer is approximately 1 order of magnitude larger than that of the NHC polymer, reflecting a larger grafting density of thiol groups on the Au surface and thus a lower K off rate for this polymer ligand. 73 We would like to note that the lower grafting density of the NHC polymer cannot be simply attributed to the steric hindrance of the carbene moieties because the larger spatial extension of the polymer coils (due to entropy consideration and excluded volume effects) will mitigate these effects.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…After careful examination of our data and analysis of the existing literature, we would like to propose a rationale that can explain the rather strong difference in the DTT test results, as shown in Figure 6 as well as in the results reported by He and coworkers. 73 Interactions between NHC groups and Au atoms are predicted to be very strong because they involve soft-to-soft Lewis base−acid interactions and the sharing of two electrons.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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N-Heterocyclic Carbene-Stabilized Gold Nanoparticles: Mono- Versus Multidentate Ligands

Nosratabad

Jin

et al. 2021

Chem. Mater.

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Over the past decade, N-heterocyclic carbenes (NHCs) have attracted remarkable attention as metal-coordinating ligands because of their ability to strongly interact with transition metal complexes and surfaces. We investigate the coordination interaction between colloidal gold nanoparticles (AuNPs) and three sets of hydrophilic NHC-based ligands: an amine-modified small molecule, a monomeric NHC appended with a poly(ethylene glycol) (PEG) block, and a modified poly(isobutylene-alt-maleic anhydride), PIMA, that simultaneously presents multiple NHC groups and several short PEG chains. In this report, we find that all three ligands can rapidly coordinate onto AuNPs, as characterized using a combination of NMR spectroscopy, high-resolution transmission electron microscopy, and dynamic light scattering. These measurements have been supplemented with colloidal stability tests as well as competition from dithiothreitol molecules. Overall, we find that multidentate NHC polymer coating exhibits the highest affinity to AuNPs, which manifests in long-term colloidal stability in buffer media, absence of any aggregation, and better resistance to competition from reducing molecules. We further exploit these data to infer additional insights into the interaction and coordination of NHC molecules with Au surfaces.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

N-Heterocyclic Carbene-Stabilized Gold Nanoparticles: Mono- Versus Multidentate Ligands

Nosratabad

Jin

et al. 2021

Chem. Mater.

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“…[ 44 , 45 ] Backbone modifications comprise long chained groups,[ 42 , 46 ] charged groups [47] and reactive groups for post‐modification. [48] Enhanced stability of AuNPs can be further achieved by implementing NHCs in polymer chains [49] and cages. [50]…”

Section: N‐heterocyclic Carbene Ligands For Gold Nanomaterialsmentioning

confidence: 99%

Catalytically Active Gold Nanomaterials Stabilized byN‐heterocyclic Carbenes

Eisen

Chin

Reithofer

2021

Chemistry An Asian Journal

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Solid supported or ligand capped gold nanomaterials (AuNMs) emerged as versatile and recyclable heterogeneous catalysts for a broad variety of conversions in the ongoing catalytic ′gold rush′. Existing at the border of homogeneous and heterogeneous catalysis, AuNMs offer the potential to merge high catalytic activity with significant substrate selectivity. Owing to their strong binding towards the surface atoms of AuMNs, NHCs offer tunable activation of surface atoms while maintaining selectivity and stability of the NM even under challenging conditions. This work summarizes well‐defined catalytically active NHC capped AuNMs including spherical nanoparticles and atom‐precise nanoclusters as well as the important NHC design choices towards activity and (stereo‐)selectivity enhancements.

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“…Additionally, a feature (though weaker) at the same chemical shift is measured for the etched NHC-PEG-QD sample, which provides proof for the formation of NHC–Zn bonds with the Zn-rich shell of the QDs (see Figure C). To further confirm the existence of this peak, HMBC NMR spectroscopy was applied to the NHC-etched QD sample . The HMBC spectrum shows a correlation between the C2 carbon atom and hydrogens in the ethyl chain at N3 which are a few bonds away (see Figure A,D).…”

Section: Results and Discussionmentioning

confidence: 99%

“…They further showed that the resulting NPs were capable of inducing trans-to-cis isomerization of azobenzene molecules. More recently, He and co-workers have prepared a few NHC-terminated polymers and reported that they can stabilize gold nanoparticle dispersions in either organic or aqueous conditions for a few months . However, these studies have mainly focused on nanocolloids made of the noble metal cores, while fewer studies have investigated the use of NHC compounds to stabilize other nanocrystals, namely fluorescent materials …”

Section: Introductionmentioning

confidence: 99%

Luminescent Quantum Dots Stabilized by N-Heterocyclic Carbene Polymer Ligands

Nosratabad

Jin

et al. 2021

J. Am. Chem. Soc.

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We have tested the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and stabilize luminescent CdSe−ZnS core−shell quantum dot (QD) dispersions in hydrophilic media. In particular, we probed the effects of ligand structure and coordination number on the coating affinity to the nanocrystals. We find that such NHC-based ligands rapidly coordinate onto the QDs (requiring ∼5−10 min of reaction time), which reflects the soft Lewis base nature of the NHC groups, with its two electrons sharing capacity. Removal of the hydrophobic cap and promotion of carbenedriven coordination on the nanocrystals have been verified by 1 H NMR spectroscopy, while 13 C NMR was used to identify the formation of carbene−Zn complexes. The newly coated QD dispersions exhibit great long-term colloidal stability over a wide range of conditions. Additionally, we find that coordination onto the QD surfaces affects the optical and spectroscopic properties of the nanocrystals. These include a size-dependent red-shift of the absorption and fluorescence spectra and a pronounced increase in the measured fluorescence intensity when the samples are stored under white light exposure compared to those stored in the dark.

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N-Heterocyclic carbene-ended polymers as surface ligands of plasmonic metal nanoparticles

Abstract: A facile methodology to prepare N-heterocyclic carbene (NHC)-terminated polymers as surface ligands to functionalize gold nanoparticles (AuNPs) is reported.

Cited by 26 publications

References 68 publications

N-Heterocyclic Carbene-Stabilized Gold Nanoparticles: Mono- Versus Multidentate Ligands

N-Heterocyclic Carbene-Stabilized Gold Nanoparticles: Mono- Versus Multidentate Ligands

Catalytically Active Gold Nanomaterials Stabilized byN‐heterocyclic Carbenes

Luminescent Quantum Dots Stabilized by N-Heterocyclic Carbene Polymer Ligands

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