Recent Advances and Prospects in Colloidal Nanomaterials

Baek, Woonhyuk; Chang, Hogeun; Bootharaju, Megalamane S.; Kim, Jeong Hyun; Park, Sung-Jun; Hyeon, Taeghwan

doi:10.1021/jacsau.1c00339

Cited by 28 publications

(40 citation statements)

References 97 publications

(168 reference statements)

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“…(right) Titration of CdSe/oleate with 6-(hexyloxy)hexylphosphinic acid. (E) General reaction scheme, (F) 1 H NMR spectra of the titration, (G) 31 P NMR after 1.0 and 1.2 equivalent phosphinic acid is added, and (H) quantification of the different compounds as a function of added equivalents.…”

Section: Resultsmentioning

confidence: 99%

“…Earlier, we also reported a general route to synthesize alkylphosphonic acids. 33 To synthesize oleylphosphonic acid for quantitative 1 H NMR titrations, we choose here to start from oleic acid, not from oleyl alcohol, since the latter is contaminated with trans isomers. First, oleic acid is reduced to oleyl alcohol, according to the procedure of Sytniczuk et al 37,69 The Appel reaction converts the alcohol in the corresponding bromide.…”

Section: Resultsmentioning

confidence: 99%

“…Colloidal nanocrystals (NCs) are an interesting materials class with a high surface-to-volume ratio. 1 Their physical and chemical properties depend on both the inorganic core and the ligandcapped surface. The ligand shell often consists of organic molecules providing colloidal stability/solubility.…”

Section: Introductionmentioning

confidence: 99%

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The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

Dhaene

Coppenolle

Deblock

et al. 2022

Preprint

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We recently introduced monoalkyl phosphinic acids as a ligand class for nanocrystal synthesis. Their metal salts have interesting reactivity differences with respect to metal carboxylates and phosphonates, and provide cleaner work-up compared to phosphonates. However, there is little known about the surface chemistry of nanocrystals with monoalkyl phosphinate ligands. Here, we probe the relative binding affinity of monoalkyl phosphinate ligands with respect to other X-type ligands. We perform competitive ligand exchange reactions with carboxylate and phosphonate ligands at the surface of HfO2, CdSe, and ZnS nanocrystals. We monitor the ligand shell composition by solution 1H and 31P NMR spectroscopy. Using a monoalkyl phosphinic acid with an ether functionality, we gain an additional NMR signature, apart from the typical alkene resonance in oleic acid and oleylphosphonic acid. We find that carboxylate ligands are easily exchanged upon exposure to monoalkyl phosphinic acids, whereas an equilibrium is reached between monoalkyl phosphinates and phosphonates, slightly in the favour of phosphonate (K = 2). Phosphinic acids have thus an intermediate binding affinity between carboxylic acids and phosphonic acids for all nanocrystals studied. These results enable the sophisticated use of monoalkyl phosphinic acids for nanocrystal synthesis and for post-synthetic surface engineering.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

Dhaene

Coppenolle

Deblock

et al. 2022

Preprint

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“…In the past three decades, colloidal semiconductor nanocrystals evolved from basic science to a prevalent material in many technological fields. [ 1–3 ] Due to their small size, typically in the range of two to tens of nanometers, they are subject to the quantum confinement effect, which enables tuning of their electronic structure via their size and dimensions. The surface of the particles is usually covered with organic surface ligands, which mediate their dispersibility in liquid media and influence their optoelectronic properties.…”

Section: Introductionmentioning

confidence: 99%

Assembly, Properties, and Application of Ordered Group II–VI and IV–VI Colloidal Semiconductor Nanoparticle Films

Micheel

Baruah

Kumar

et al. 2022

Adv Materials Inter

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“…Atomically precise clusters are valuable building blocks for material science. 1,2 [3][4][5][6][7] Clusters are used to build stimuli-responsive materials, 8 or hierarchical (porous) structures. 9,10 Clusters can be precursors or intermediates in nanocrystal synthesis.…”

Section: Introductionmentioning

confidence: 99%

Fatty acid capped, metal oxo clusters as smallest conceivable nanocrystal prototypes

Enyden

Pokratath

Mathew

et al. 2022

Preprint

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Metal oxo clusters of the type \ce{M6O4(OH)4(RCOO)12} (M = Zr of Hf) are valuable building blocks for material science. Here, we develop them as smallest conceivable nanocrystal prototypes. We synthesize a series of zirconium and hafnium oxo clusters with ligands that are typically used to stabilize oxide nanocrystals (fatty acids with long and/or branched chains). In contrast to previously reported discrete oxo clusters with short/rigid carboxylates (e.g., acetate, benzoate), the fatty acid capped oxo clusters have a high solubility but do not crystallize, precluding traditional purification and single-crystal XRD analysis of clusters. We thus develop alternative purification strategies and structural analysis tools. We use X-ray total scattering and Pair Distribution Function (PDF) analysis as our main tool to elucidate the structure of the cluster core. In contrast to traditional PDF analysis of larger clusters and nanocrystals, we show that the structure models need to include the carboxylate binding groups to obtain excellent refinements. Our methodology is able to pick up the correct structure from a series of possible structure models (\textbf{Zr4}, \textbf{Zr6}, \textbf{Zr12}). Further supporting evidence for the cluster composition (including their ligand shell) is provided by nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and mass spectrometry (MS). We find that the ligands have multiple binding modes and that hydrogen bonded carboxylic acid is an intrinsic part of the oxo cluster. Using our analytical tools, we elucidate the conversion from \textbf{Zr6} monomer to \textbf{Zr12} dimer (and vice versa), induced by carboxylate ligand exchange. Finally, we compared the catalytic performance of \textbf{Zr12}-oleate clusters with oleate capped, 3-5 nm zirconium oxide nanocrystals in the esterification of oleic acid with ethanol. The oxo clusters are much more catalytically active, due to their higher surface area. Since the oxo clusters are the limit of downscaling oxide nanocrystals, we thus propose them here as appealing catalytic materials, or at least as atomically precise model systems. In addition, our analytical (PDF) methodology is generally applicable and expected to find use in other areas of clusters as well, and will be especially valuable for clusters with weakly scattering core atoms.

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Recent Advances and Prospects in Colloidal Nanomaterials

Cited by 28 publications

References 97 publications

The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

Assembly, Properties, and Application of Ordered Group II–VI and IV–VI Colloidal Semiconductor Nanoparticle Films

Fatty acid capped, metal oxo clusters as smallest conceivable nanocrystal prototypes

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