Resorcin[4]arene-based multidentate phosphate ligands with superior binding affinity for nanocrystal surfaces

Nemat, Suren J.; Eynden, Dietger Van den; Deblock, Loren; Heilmann, Michael; Köster, Jesper M.; Parvizian, Mahsa; Tiefenbacher, Konrad; Roo, Jonathan De

doi:10.1039/d1cc00223f

Cited by 7 publications

(8 citation statements)

References 38 publications

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“…We installed four phosphates either on the top or the bottom rim; see Figure 10. 101 By carefully titrating oleate capped zirconia nanocrystals with the macrocyclic ligands, we found that both our macrocycles are at least tridentate (possibly tetradentate) at low ligand coverage. However, the macrocyclic ligands need three/four adjacent free binding sites to bind according to its maximal denticity.…”

Section: Ligand Design Toward High Binding Affinitymentioning

confidence: 84%

The Surface Chemistry of Colloidal Nanocrystals Capped by Organic Ligands

Roo

2023

Chem. Mater.

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Nanocrystal surface chemistry is a pivotal element in the synthesis and application of nanocrystals. This perspective focuses on colloidal nanocrystals, capped with organic ligands. We start with insights into a workhorse characterization technique: solution nuclear magnetic resonance (NMR) spectroscopy. We then discuss the different models used to conceptualize nanocrystal surface chemistry and how the classification of binding motifs helps in the prediction of surface reactions. The thermodynamics and kinetics of these surface reactions are analyzed, and we arrive at the deciding factors for a high binding affinity: sterics, pK a/pK b, and solubility/solvent. Finally, we discuss recent ligand designs; most notably we introduce a new ligand class: monoalkyl phosphinic acids.

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Section: Ligand Design Toward High Binding Affinitymentioning

confidence: 84%

The Surface Chemistry of Colloidal Nanocrystals Capped by Organic Ligands

Roo

2023

Chem. Mater.

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“…In addition to proton transfer, other factors also play a role in an X-type exchange. Steric bulk can hamper ligand exchange, multidentate ligands feature enhanced binding affinity, − and the ligand solubility can also steer the exchange reaction. , The binding enthalpy of an X-type ligand can be particularly high for certain surfaces but low for other surfaces due to chemical compatibility. For example, thiols have a high affinity for the surface of metal chalcogenide or metallic NCs but are generally poor ligands for metal oxides. ,,,,− Finally, a ligand exchange reaction can be forced by the formation of energetically favorable byproducts.…”

Section: Introductionmentioning

confidence: 99%

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

et al. 2023

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We recently introduced monoalkyl phosphinic acids as a ligand class for nanocrystal (NC) synthesis. Their metal salts have interesting reactivity differences compared to metal carboxylates and phosphonates and provide a cleaner work-up compared to phosphonates. However, little is known about the surface chemistry of NCs 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 hafnia, cadmium selenide, and zinc sulfide NCs. We monitor the ligand shell composition by solution 1 H and 31 P 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 favor of phosphonate (K = 2). Phosphinic acids have thus an intermediate binding affinity between carboxylic acids and phosphonic acids for all the NCs studied. These results enable the sophisticated use of monoalkyl phosphinic acids for NC synthesis and for post-synthetic surface engineering.

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“…[20][21] Phosphonates and phosphates are among the strongest ligands available and easily displace carboxylic acids, 13,[22][23] especially when designed as multidentate ligands on a scaffold. [24][25] Phosphonic acids are also the ligands of choice for high temperature (> 300 °C) quantum dot syntheses. Peng et al used a mixture of saturated phosphonic acids to synthesize CdE (E = S, Se or Te) NCs and nanorods.…”

Section: Introductionmentioning

confidence: 99%

“…Metal oleates are stable metal precursors for quantum dot syntheses at relatively low temperatures (240 °C). , At higher temperatures they often decompose to metals or metal oxides. , Oleylamine is a typical L-type ligand and usually binds in a dynamic fashion . In very specific systems, oleylamine can be a tightly bound ligand. , Phosphonates and phosphates are among the strongest ligands available and easily displace carboxylic acids, ,, especially when designed as multidentate ligands on a scaffold. , Phosphonic acids are also the ligands of choice for high-temperature (>300 °C) quantum dot syntheses. Peng et al used a mixture of saturated phosphonic acids to synthesize CdE (E = S, Se, or Te) NCs and nanorods .…”

Section: Introductionmentioning

confidence: 99%

Monoalkyl Phosphinic Acids as Ligands in Nanocrystal Synthesis

et al. 2022

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Ligands play a crucial role in the synthesis of colloidal nanocrystals. Nevertheless, only a handful molecules are currently used, oleic acid being the most typical example. Here, we show that mono-alkyl phosphinic acids are another interesting ligand class, forming metal complexes with a reactivity that is intermediate between the traditional carboxylates and phosphonates.We first present the synthesis of n-hexyl, 2-ethylhexyl, n-tetradecyl, n-octadecyl, and oleyl phosphinic acid. These compounds are suitable ligands for high-temperature nanocrystal synthesis (240-300°C) since, in contrast to phosphonic acids, they do not form anhydride oligomers. Consequently, CdSe quantum dots synthesized with octadecylphosphinic acid are conveniently purified, and their UV-Vis spectrum is free from background scattering. The CdSe nanocrystals have a low polydispersity and a photoluminescence quantum yield up to 18%. Furthermore, we could synthesize CdSe and CdS nanorods using phosphinic acid ligands, with high shape purity. We conclude that the reactivity towards TOP-S and TOP-Se precursors decreases in the series: cadmium carboxylate > cadmium phosphinate > cadmium phosphonate.By introducing a third and intermediate class of surfactants, we enhance the versatility of surfactant-assisted syntheses.

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Resorcin[4]arene-based multidentate phosphate ligands with superior binding affinity for nanocrystal surfaces

Abstract: We synthesized two resorcin[4]arene scaffolds with four phosphate binding groups. The superior binding affinity to nanocrystal surfaces is demonstrated using solution NMR spectroscopy and exceeds that of single phosphonates.

Cited by 7 publications

References 38 publications

The Surface Chemistry of Colloidal Nanocrystals Capped by Organic Ligands

The Surface Chemistry of Colloidal Nanocrystals Capped by Organic Ligands

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

Monoalkyl Phosphinic Acids as Ligands in Nanocrystal Synthesis

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