Thermodynamics of nanocrystal–ligand binding through isothermal titration calorimetry

Greytak, Andrew B.; Abiodun, Sakiru L.; Burrell, Jennii M; Cook, Emily N; Jayaweera, Nuwanthaka P.; Islam, Monirul; Shaker, Abdulla E

doi:10.1039/d2cc05012a

Cited by 11 publications

(10 citation statements)

References 251 publications

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“…Recently, a modified Ising model was developed based on ITC data to account for varying ligand–ligand interactions during the exchange . Unlike our quantification based on NMR, ITC does not suffer from poor resolution at the start of the titration and might be better suitable to support a more complex modeling approach. ,,,,− …”

Section: Resultsmentioning

confidence: 99%

“…Advanced methods such as diffusion-ordered spectroscopy (DOSY) are used to probe the dynamics of ligand binding . On the other hand, isothermal titration calorimetry (ITC) has been recently used as a powerful, complementary technique to investigate ligand exchange reactions. ,,,,− It has the advantage of providing direct thermodynamic data by accurately measuring small heat changes. It does not provide the composition of the ligand shell nor does it identify free ligands in solutions …”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

et al. 2023

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“…All curves were fitted to a single-site exchange reaction model, presented in our previous work . This model considers both the detachment of the native oleate ligand and the binding of the alkylthiol, similar to the approaches recently presented in other models for exchange reactions on the NC surface, − thus allowing to extract a single set of thermodynamic parameters, including the reaction enthalpy (Δ H ), entropy (Δ S ), and Gibbs free energy (Δ G ) (SI, Section 4). Although the NC surface is expected to contain multiple types of surface sites, , this heterogeneity is apparently masked in the binary shell, probably due to the expected sparser packing (as will be discussed in the following), which resulted in thermodynamically identical facet and edge surface sites.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Patterning of Binary Ligand Mixtures on CdSe Nanocrystals: From Random to Janus Packing

et al. 2023

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Binary compositions of surface ligands are known to improve the colloidal stability and fluorescence quantum yield of nanocrystals (NCs), due to ligand−ligand interactions and surface organization. Herein, we follow the thermodynamics of a ligand exchange reaction of CdSe NCs with alkylthiol mixtures. The effects of ligand polarity and length difference on ligand packing were investigated using isothermal titration calorimetry (ITC). The thermodynamic signature of the formation of mixed ligand shells was observed. Correlating the experimental results with thermodynamic mixing models has allowed us to calculate the interchain interactions and to infer the final ligand shell configuration. Our findings demonstrate that, in contrast to macroscopic surfaces, the small dimensions of the NCs and the subsequent increased interfacial region between dissimilar ligands allow the formation of a myriad of clustering patterns, controlled by the interligand interactions. This work provides a fundamental understanding of the parameters determining the ligand shell structure and should help guide smart surface design toward NC-based applications.

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“…ITC dilution experiments were then carried out to characterize the self-assembly equilibrium. [26][27][28][29] For these experiments we a concentrated solution of 1 in CHCl 3 , with predominately aggregated monomers, into the pure solvent to cause partial dissociation. Figure 5a shows a representative thermogram.…”

Section: Methodsmentioning

confidence: 99%

Two‐Dimensional Supramolecular Polymerization of a Bis‐Urea Macrocycle into a Brick‐Like Hydrogen‐Bonded Network

Rubert,

Islam,

Greytak

et al. 2023

Angew Chem Int Ed

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We report on a dendronized bis‐urea macrocycle 1 self‐assembling via a cooperative mechanism into two‐dimensional (2D) nanosheets formed solely by alternated urea‐urea hydrogen bonding interactions. The pure macrocycle self‐assembles in bulk into one‐dimensional liquid‐crystalline columnar phases. In contrast, its self‐assembly mode drastically changes in CHCl3 or tetrachloroethane leading to 2D hydrogen‐bonded networks. Theoretical calculations, complemented by previously reported crystalline structures, indicate that the 2D assembly is formed by a brick‐like hydrogen bonding pattern between bis‐urea macrocycles. This assembly is promoted by the swelling of the trisdodecyloxyphenyl groups upon solvation, which frustrates, due to steric effects, the formation of the thermodynamically more stable columnar macrocycle stacks. This work proposes a new design strategy to access 2D supramolecular polymers by means of a single non‐covalent interaction motif, which is of great interest for materials development.

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Thermodynamics of nanocrystal–ligand binding through isothermal titration calorimetry

Abstract: Manipulations of nanocrystal (NC) surfaces have propelled the applications of colloidal NCs across various fields such as bioimaging, catalysis, electronics, and sensing applications.

Cited by 11 publications

References 251 publications

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

Spontaneous Patterning of Binary Ligand Mixtures on CdSe Nanocrystals: From Random to Janus Packing

Two‐Dimensional Supramolecular Polymerization of a Bis‐Urea Macrocycle into a Brick‐Like Hydrogen‐Bonded Network

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