1
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Upah A, Thomas A, Hallstrom J, Travesset A. High-Precision Calculation of Nanoparticle (Nanocrystal) Potentials of Mean Force and Internal Energies. J Chem Theory Comput 2024; 20:1559-1567. [PMID: 37956245 DOI: 10.1021/acs.jctc.3c00749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Thermodynamic stability assessment of nanocrystal systems requires precise free energy calculations. This study highlights the importance of meticulous control over various factors, including the thermostat, time step, potential cutoff, initial configuration, sampling method, and overall simulation duration. Free energy computations in dry (solvent-free) systems are on the order of several hundred kBT but can be obtained with consistent accuracy. However, calculation of internal energies becomes challenging, as they are typically much larger in magnitude than free energies and exhibit significant noise and reduced reliability. To address this limitation, we propose a new internal energy estimate that drastically reduces the noise. We also present formulas that enable the optimization of the parameters of the harmonic bias potential for optimal convergence. Finally, we discuss the implications of these findings for the computation of free energies in nanocrystal clusters and superlattices.
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Affiliation(s)
- Alex Upah
- Department of Physics and Astronomy, Iowa State University and Ames National Laboratory, Ames, Iowa 50011, United States
| | - Andrew Thomas
- Department of Physics and Astronomy, Iowa State University and Ames National Laboratory, Ames, Iowa 50011, United States
| | - Jonas Hallstrom
- Department of Physics and Astronomy, Iowa State University and Ames National Laboratory, Ames, Iowa 50011, United States
| | - Alex Travesset
- Department of Physics and Astronomy, Iowa State University and Ames National Laboratory, Ames, Iowa 50011, United States
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2
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Liu M, Tang G, Liu Y, Jiang FL. Ligand Exchange of Quantum Dots: A Thermodynamic Perspective. J Phys Chem Lett 2024; 15:1975-1984. [PMID: 38346356 DOI: 10.1021/acs.jpclett.3c03413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Colloidal quantum dots (QDs) consist of an inorganic core and organic surface ligands. Surface ligands play a dominant role in maintaining the colloidal stability of QDs and passivating the surface defects of QDs. However, the original ligands introduced in the synthetic process of QDs cannot meet the requirements for diverse applications; therefore, ligand exchanges with functional ligands are mandatory. Understanding the ligand exchange process requires a comprehensive combination of the concepts and techniques of surface chemistry. In this Perspective, the ligand exchange process is discussed in detail. Specifically, we elaborate on the thermodynamics that can reveal the feasibility and mechanism of ligand exchange. It depicts a critical physical picture of the surface of QDs along with the following ligand exchange.
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Affiliation(s)
- Meng Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Ge Tang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Yi Liu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
- State Key Laboratory of Separation Membranes and Membrane Processes, School of Chemistry, Tiangong University, Tianjin 300387, P. R. China
| | - Feng-Lei Jiang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
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3
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Varshney S, Oded M, Remennik S, Gutkin V, Banin U. Controlling the Surface of Aluminum Nanocrystals: From Aluminum Oxide to Aluminum Fluoride. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2304478. [PMID: 37420322 DOI: 10.1002/smll.202304478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 07/09/2023]
Abstract
Aluminum nanocrystals are emerging as a promising alternative to silver and gold for various applications ranging from plasmonic functionalities to photocatalysis and as energetic materials. Such nanocrystals often exhibit an inherent surface oxidation layer, as aluminum is highly reactive. Its controlled removal is challenging but required, as it can hinder the properties of the encaged metal. Herein, two wet-chemical colloidal approaches toward the surface coating of Al nanocrystals, which afford control over the surface chemistry of the nanocrystals and the oxide thickness, are presented. The first approach utilizes oleic acid as a surface ligand by its addition toward the end of the Al nanocrystals synthesis, and the second approach is the post-synthesis treatment of Al nanocrystals with NOBF4 , in a "wet" colloidal-based approach, which is found to etch and fluorinate the surface oxides. As surface chemistry is an important handle for controlling materials' properties, this research paves a path for manipulating Al nanocrystals while promoting their utilization in diverse applications.
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Affiliation(s)
- Shalaka Varshney
- The Institute of Chemistry and the Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Meirav Oded
- The Institute of Chemistry and the Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Sergei Remennik
- The Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Vitaly Gutkin
- The Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
| | - Uri Banin
- The Institute of Chemistry and the Center for Nanoscience & Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel
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4
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Charlton BK, Downie DH, Noman I, Alves PU, Eling CJ, Laurand N. Surface Functionalisation of Self-Assembled Quantum Dot Microlasers with a DNA Aptamer. Int J Mol Sci 2023; 24:14416. [PMID: 37833863 PMCID: PMC10572750 DOI: 10.3390/ijms241914416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
The surface functionalisation of self-assembled colloidal quantum dot supraparticle lasers with a thrombin binding aptamer (TBA-15) has been demonstrated. The self-assembly of CdSSe/ZnS alloyed core/shell microsphere-shape CQD supraparticles emitting at 630 nm was carried out using an oil-in-water emulsion technique, yielding microspheres with an oleic acid surface and an average diameter of 7.3 ± 5.3 µm. Surface modification of the microspheres was achieved through a ligand exchange with mercaptopropionic acid and the subsequent attachment of TBA-15 using EDC/NHS coupling, confirmed by zeta potential and Fourier transform IR spectroscopy. Lasing functionality between 627 nm and 635 nm was retained post-functionalisation, with oleic acid- and TBA-coated microspheres exhibiting laser oscillation with thresholds as low as 4.10 ± 0.37 mJ·cm-2 and 7.23 ± 0.78 mJ·cm-2, respectively.
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Affiliation(s)
| | | | | | | | | | - Nicolas Laurand
- Technology & Innovation Centre, Institute of Photonics, University of Strathclyde, 99 George Street, Glasgow G1 1RD, UK; (B.K.C.); (D.H.D.); (I.N.); (P.U.A.); (C.J.E.)
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5
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Mahmood AU, Rizvi MH, Tracy JB, Yingling YG. Solvent Effects in Ligand Stripping Behavior of Colloidal Nanoparticles. ACS NANO 2023. [PMID: 37311219 DOI: 10.1021/acsnano.3c01313] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Inorganic colloidal nanoparticle (NP) properties can be tuned by stripping stabilizing ligands using a poor solvent. However, the mechanism behind ligand stripping is poorly understood, in part because in situ measurements of ligand stripping are challenging at the nanoscale. Here, we investigate ethanol solvent-mediated oleylamine ligand stripping from magnetite (Fe3O4) NPs in different compositions of ethanol/hexane mixtures using atomistic molecular dynamics (MD) simulations and thermogravimetric analysis (TGA). Our study elucidates a complex interplay of ethanol interactions with system components and indicates the existence of a threshold concentration of ∼34 vol % ethanol, above which ligand stripping saturates. Moreover, hydrogen bonding between ethanol and stripped ligands inhibits subsequent readsorption of the ligands on the NP surface. A proposed modification of the Langmuir isotherm explains the role of the enthalpy of mixing of the ligands and solvents on the ligand stripping mechanism. A good agreement between the MD predictions and TGA measurements of ligand stripping from Fe3O4 NPs validates the simulation observations. Our findings demonstrate that the ligand coverage of NPs can be controlled by using a poor solvent below the threshold concentration and highlight the importance of ligand-solvent interactions that modulate the properties of colloidal NPs. The study also provides an approach for a detailed in silico study of ligand stripping and exchange from colloidal NPs that are crucial for applications of NPs spanning self-assembly, optoelectronics, nanomedicine, and catalysis.
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Affiliation(s)
- Akhlak U Mahmood
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Mehedi H Rizvi
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Joseph B Tracy
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Yaroslava G Yingling
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
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6
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Fenoll D, Sodupe M, Solans-Monfort X. Influence of Capping Ligands, Solvent, and Thermal Effects on CdSe Quantum Dot Optical Properties by DFT Calculations. ACS OMEGA 2023; 8:11467-11478. [PMID: 37008094 PMCID: PMC10061629 DOI: 10.1021/acsomega.3c00324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
Cadmium selenide nanomaterials are very important materials in photonics, catalysis, and biomedical applications due to their optical properties that can be tuned through size, shape, and surface passivation. In this report, static and ab initio molecular dynamics density functional theory (DFT) simulations are used to characterize the effect of ligand adsorption on the electronic properties of the (110) surface of zinc blende and wurtzite CdSe and a (CdSe)33 nanoparticle. Adsorption energies depend on ligand surface coverage and result from a balance between chemical affinity and ligand-surface and ligand-ligand dispersive interactions. In addition, while little structural reorganization occurs upon slab formation, Cd···Cd distances become shorter and the Se-Cd-Se angles become smaller in the bare nanoparticle model. This originates mid-gap states that strongly influence the absorption optical spectra of nonpassivated (CdSe)33. Ligand passivation on both zinc blende and wurtzite surfaces does not induce a surface reorganization, and thus, the band gap remains nonaffected with respect to bare surfaces. In contrast, structural reconstruction is more apparent for the nanoparticle, which significantly increases its highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap upon passivation. Solvent effects decrease the band gap difference between the passivated and nonpassivated nanoparticles, the maximum of the absorption spectra being blue-shifted around 20 nm by the effect of the ligands. Overall, calculations show that flexible surface cadmium sites are responsible for the appearance of mid-gap states that are partially localized on the most reconstructed regions of the nanoparticle that can be controlled through appropriate ligand adsorption.
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7
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Elimelech O, Oded M, Harries D, Banin U. Spontaneous Patterning of Binary Ligand Mixtures on CdSe Nanocrystals: From Random to Janus Packing. ACS NANO 2023; 17:5852-5860. [PMID: 36893308 PMCID: PMC10061916 DOI: 10.1021/acsnano.2c12676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
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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Affiliation(s)
- Orian Elimelech
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Meirav Oded
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Daniel Harries
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
- The
Fritz Haber Center, The Hebrew University
of Jerusalem, Jerusalem 9190401, Israel
| | - Uri Banin
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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8
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Zhou X, Pang Z, Cao W, Cao Z, Zhu J, Qi Y, Peng X, Kong X. Diffusion NMR for Measuring Dynamic Ligand Exchange on Colloidal Nanocrystals. Anal Chem 2023; 95:792-801. [PMID: 36520837 DOI: 10.1021/acs.analchem.2c02964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ligand exchange is fundamentally related to the surface chemistry of nanoparticles in solution and is also an essential procedure for their synthesis and solution processing. The solution of ligand-bearing nanoparticles can be regarded as a dynamic equilibrium of bound and free ligands depending on the concentration and temperature. The direct experimental calibration of the ligand exchange dynamics relies on the in situ and real-time quantification of bound and free ligands. However, existing analytical strategies are often with limited applicability considering the requirement of special functional groups or the indirect detection of photoluminescence or reaction heat. In this work, we explore diffusion-based methods of solution-state nuclear magnetic resonance (NMR) as a general strategy to probe ligand exchange. Using comprehensive numerical simulations, we show that diffusion NMR with designable time sequences can effectively distinguish bound and free ligands and measure the exchange rate constants from 0.5 to 200 s-1 under typical instrumental settings. These methods are demonstrated experimentally on colloidal CdSe nanocrystal systems with carboxylate or amine ligands whose exchange rates were previously undetectable. The kinetic rate constants, activation energies, and thermodynamic parameters of ligand exchange have been obtained under variable temperature conditions. We expect the diffusion NMR strategies to be generally applicable for calibrating the exchange of organic ligands on various nanoparticle systems.
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Affiliation(s)
- Xiaoqi Zhou
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Zhenfeng Pang
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Weicheng Cao
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Zhenming Cao
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Jie Zhu
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Yixin Qi
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Xiaogang Peng
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
| | - Xueqian Kong
- Department of Chemistry, Zhejiang University, Hangzhou310027, China.,Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou310027, China
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9
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Behera P, Karunakaran S, Sahoo J, Bhatt P, Rana S, De M. Ligand Exchange on MoS 2 Nanosheets: Applications in Array-Based Sensing and Drug Delivery. ACS NANO 2022; 17:1000-1011. [PMID: 36482513 DOI: 10.1021/acsnano.2c06994] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional MoS2 nanosheets (2D-MoS2) have been widely used in many biological applications due to their distinctive physicochemical properties. Further, the development of surface modification using thiolated ligands allows us to use them for many specific applications. But the effect of possible ligand exchange on 2D-MoS2 has never been explored, which can play an important role in diverse biological applications. In this study, we have observed the ligand-exchange phenomenon on 2D-MoS2 in the presence of different thiolated ligands. The initial study proceeded with boron-dipyrromethene (BODIPY) functionalized MoS2 with different concentrations of glutathione (GSH), which is the most abundant thiol species in the cytoplasm of various cancer cells. It was found that in the presence of GSH the fluorescence of BODIPY can be regenerated, which is time and concentration dependent. We have also examined this phenomenon with different thiol ligands and transition-metal dichalcogenides (TMDs). We observed a variable rate of ligand exchange in different solvents, surface functionality, and receptor environments that helped us to construct sensor arrays. Interestingly, a ligand-exchange process was not observed in the presence of dithiols. Further, this concept was applied to a cancerous cell line for in vitro delivery. We found that BODIPY-functionalized 2D-MoS2 undergoes thiol exchange by intracellular GSH and subsequently enhanced the fluorescence in the cytoplasm of cancer cells. This strategy can be applied to the development of 2D-TMD-based materials for various biological applications related to ligand exchange.
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Affiliation(s)
- Pradipta Behera
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Subbaraj Karunakaran
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Jagabandhu Sahoo
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Preeti Bhatt
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Subinoy Rana
- Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Mrinmoy De
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
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10
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Scharf E, Krieg F, Elimelech O, Oded M, Levi A, Dirin DN, Kovalenko MV, Banin U. Ligands Mediate Anion Exchange between Colloidal Lead-Halide Perovskite Nanocrystals. NANO LETTERS 2022; 22:4340-4346. [PMID: 35605286 PMCID: PMC9185745 DOI: 10.1021/acs.nanolett.2c00611] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/05/2022] [Indexed: 05/31/2023]
Abstract
The soft lattice of lead-halide perovskite nanocrystals (NCs) allows tuning their optoelectronic characteristics via anion exchange by introducing halide salts to a solution of perovskite NCs. Similarly, cross-anion exchange can occur upon mixing NCs of different perovskite halides. This process, though, is detrimental for applications requiring perovskite NCs with different halides in close proximity. We study the effects of various stabilizing surface ligands on the kinetics of the cross-anion exchange reaction, comparing zwitterionic and ionic ligands. The kinetic analysis, inspired by the "cage effect" for solution reactions, showcases a mechanism where the surface capping ligands act as anion carriers that diffuse to the NC surface, forming an encounter pair enclosed by the surrounding ligands that initiates the anion exchange process. The zwitterionic ligands considerably slow down the cross-anion exchange process, and while they do not fully inhibit it, they confer improved stability alongside enhanced solubility relevant for various applications.
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Affiliation(s)
- Einav Scharf
- The
Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Franziska Krieg
- Institute
of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 1, Zürich CH-8093, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, Dübendorf CH-8600, Switzerland
| | - Orian Elimelech
- The
Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Meirav Oded
- The
Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Adar Levi
- The
Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Dmitry N. Dirin
- Institute
of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 1, Zürich CH-8093, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, Dübendorf CH-8600, Switzerland
| | - Maksym V. Kovalenko
- Institute
of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 1, Zürich CH-8093, Switzerland
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, Dübendorf CH-8600, Switzerland
| | - Uri Banin
- The
Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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11
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Deshmukh SH, Chatterjee S, Ghosh D, Bagchi S. Ligand Dynamics Time Scales Identify the Surface-Ligand Interactions in Thiocyanate-Capped Cadmium Sulfide Nanocrystals. J Phys Chem Lett 2022; 13:3059-3065. [PMID: 35352931 DOI: 10.1021/acs.jpclett.2c00493] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The nanocrystal surface, which acts as an interface between the semiconductor lattice and the capping ligands, plays a significant role in the attractive photophysical properties of semiconductor nanocrystals for use in a wide range of applications. Replacing the long-chain organic ligands with short inorganic variants improves the conductivity and carrier mobility of nanocrystal-based devices. However, our current understanding of the interactions between the inorganic ligands and the nanocrystals is obscure due to the lack of experiments to directly probe the inorganic ligands. Herein, using two-dimensional infrared spectroscopy, we show that the variations in the inorganic ligand dynamics within the heterogeneous nanocrystal ensemble can identify the diversities in the inorganic ligand-nanocrystal interactions. The ligand dynamics time scale in SCN- capped CdS nanocrystals identifies three distinct ligand populations and provides molecular insight into the nanocrystal surface. Our results demonstrate that the SCN- ligands engage in a dynamic equilibrium and stabilize the nanocrystals by neutralizing the surface charges through both direct binding and electrostatic interaction.
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Affiliation(s)
- Samadhan H Deshmukh
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Srijan Chatterjee
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Deborin Ghosh
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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12
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Arildii D, Kim K, Lee Y, Choi H, Jang C, Eom SH, Mun SA, Yoon SC, Jin SH, Park J, Kim B. Highly Sensitive and Durable Organic Photodiodes Based on Long-Term Storable NiO x Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2022; 14:14410-14421. [PMID: 35312277 DOI: 10.1021/acsami.2c01693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Organic optoelectronic devices that can be fabricated at low cost have attracted considerable attention because they can absorb light over a wide frequency range and have high conversion efficiency, as well as being lightweight and flexible. Moreover, their performance can be significantly affected by the choice of the charge-selective interlayer material. Nonstoichiometric nickel oxide (NiOx) is an excellent material for the hole-transporting layer (HTL) of organic optoelectronic devices because of the good alignment of its valence band position with the highest occupied molecular orbital level of many p-type polymers. Herein, we report a simple low-temperature process for the synthesis of NiOx nanoparticles (NPs) that can be well dispersed in solution for long-term storage and easily used to form thin NiOx NP layers. NiOx NP-based organic photodiode (OPD) devices demonstrated high specific detectivity (D*) values of 1012-1013 jones under various light intensities and negative biases. The D* value of the NiOx NP-based OPD device was 4 times higher than that of a conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based device, an enhancement that originated mainly from the 16 times decreased leakage current. The NiOx NP-based OPD device demonstrated better reliability over a wide range of light intensities and operational biases in comparison to a device with a conventional sol-gel-processed NiOx film. More importantly, the NiOx NP-based OPD showed long-term device stability superior to those of the PEDOT:PSS and sol-gel-processed NiOx-based devices. We highlight that our low-temperature solution-processable NiOx NP-based HTL could become a crucial component in the fabrication of stable high-performance OPDs.
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Affiliation(s)
- Dashjargal Arildii
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kangyong Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Youngwan Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Huijeong Choi
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Changhee Jang
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Seung Hun Eom
- Division of Advanced Materials, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
| | - Sang A Mun
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Sung Cheol Yoon
- Division of Advanced Materials, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea
| | - Sung-Ho Jin
- Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busan 46241, Republic of Korea
| | - Jongnam Park
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - BongSoo Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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13
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Elimelech O, Aviv O, Oded M, Peng X, Harries D, Banin U. Entropy of Branching Out: Linear versus Branched Alkylthiols Ligands on CdSe Nanocrystals. ACS NANO 2022; 16:4308-4321. [PMID: 35157440 PMCID: PMC8945696 DOI: 10.1021/acsnano.1c10430] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Surface ligands of semiconductor nanocrystals (NCs) play key roles in determining their colloidal stability and physicochemical properties and are thus enablers also for the NCs flexible manipulation toward numerous applications. Attention is usually paid to the ligand binding group, while the impact of the ligand chain backbone structure is less discussed. Using isothermal titration calorimetry (ITC), we studied the effect of structural changes in the ligand chain on the thermodynamics of the exchange reaction for oleate coated CdSe NCs, comparing linear and branched alkylthiols. The investigated alkylthiol ligands differed in their backbone length, branching position, and branching group length. Compared to linear ligands, lower exothermicity and entropy loss were observed for an exchange with branched ligands, due to steric hindrance in ligand packing, thereby justifying their previous classification as "entropic ligands". Mean-field calculations for ligand binding demonstrate the contribution to the overall entropy originating from ligand conformational entropy, which is diminished upon binding mainly by packing of NC-bound ligands. Model calculations and the experimental ITC data both point to an interplay between the branching position and the backbone length in determining the entropic nature of the branched ligand. Our findings suggest that the most entropic ligand should be a short, branched ligand with short branching group located toward the middle of the ligand chain. The insights provided by this work also contribute to a future smarter NC surface design, which is an essential tool for their implementation in diverse applications.
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Affiliation(s)
- Orian Elimelech
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Omer Aviv
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Meirav Oded
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Xiaogang Peng
- Department
of Chemistry, Zhejiang University, Hangzhou 310027 P. R. China
| | - Daniel Harries
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
- The
Fritz Haber Center, The Hebrew University
of Jerusalem, Jerusalem 9190401, Israel
| | - Uri Banin
- The
Institute of Chemistry and The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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14
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Huang Y, Cohen TA, Sperry BM, Larson H, Nguyen HA, Homer MK, Dou FY, Jacoby LM, Cossairt BM, Gamelin DR, Luscombe CK. Organic building blocks at inorganic nanomaterial interfaces. MATERIALS HORIZONS 2022; 9:61-87. [PMID: 34851347 DOI: 10.1039/d1mh01294k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This tutorial review presents our perspective on designing organic molecules for the functionalization of inorganic nanomaterial surfaces, through the model of an "anchor-functionality" paradigm. This "anchor-functionality" paradigm is a streamlined design strategy developed from a comprehensive range of materials (e.g., lead halide perovskites, II-VI semiconductors, III-V semiconductors, metal oxides, diamonds, carbon dots, silicon, etc.) and applications (e.g., light-emitting diodes, photovoltaics, lasers, photonic cavities, photocatalysis, fluorescence imaging, photo dynamic therapy, drug delivery, etc.). The structure of this organic interface modifier comprises two key components: anchor groups binding to inorganic surfaces and functional groups that optimize their performance in specific applications. To help readers better understand and utilize this approach, the roles of different anchor groups and different functional groups are discussed and explained through their interactions with inorganic materials and external environments.
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Affiliation(s)
- Yunping Huang
- Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195, USA.
| | - Theodore A Cohen
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Breena M Sperry
- Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195, USA.
| | - Helen Larson
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Hao A Nguyen
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Micaela K Homer
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Florence Y Dou
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Laura M Jacoby
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Christine K Luscombe
- Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195, USA.
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA 98195, USA
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
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15
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Greytak AB, Abiodun SL, Burrell JM, Cook EN, Jayaweera NP, Islam MM, Shaker AE. Thermodynamics of nanocrystal–ligand binding through isothermal titration calorimetry. Chem Commun (Camb) 2022; 58:13037-13058. [DOI: 10.1039/d2cc05012a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Manipulations of nanocrystal (NC) surfaces have propelled the applications of colloidal NCs across various fields such as bioimaging, catalysis, electronics, and sensing applications.
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Affiliation(s)
- Andrew B. Greytak
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Sakiru L. Abiodun
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Jennii M. Burrell
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Emily N. Cook
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Nuwanthaka P. Jayaweera
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Md Moinul Islam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Abdulla E Shaker
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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16
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Yue Y, Liu S, Zhang N, Su Z, Zhu D. Molecular engineering of s-triazine and its derivatives applied in surface modification strategy for enhancing photoelectric performance of all-inorganic perovskites. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.06.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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17
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Jansen M, Juranyi F, Yarema O, Seydel T, Wood V. Ligand Dynamics in Nanocrystal Solids Studied with Quasi-Elastic Neutron Scattering. ACS NANO 2021; 15:20517-20526. [PMID: 34878757 DOI: 10.1021/acsnano.1c09073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanocrystal surfaces are commonly populated by organic ligands, which play a determining role in the optical, electronic, thermal, and catalytic properties of the individual nanocrystals and their assemblies. Understanding the bonding of ligands to nanocrystal surfaces and their dynamics is therefore important for the optimization of nanocrystals for different applications. In this study, we use temperature-dependent, quasi-elastic neutron scattering (QENS) to investigate the dynamics of different surface bound alkanethiols in lead sulfide nanocrystal solids. We select alkanethiols with mono- and dithiol terminations, as well as different backbone types and lengths. QENS spectra are collected both on a time-of-flight spectrometer and on a backscattering spectrometer, allowing us to investigate ligand dynamics in a time range from a few picoseconds to nanoseconds. Through model-based analysis of the QENS data, we find that ligands can either (1) precess around a central axis, while simultaneously rotating around their own molecular axis, or (2) only undergo uniaxial rotation with no precession. We establish the percentage of ligands undergoing each type of motion, the average relaxation times, and activation energies for these motions. We determine, for example, that dithiols which link facets of neighboring nanocrystals only exhibit uniaxial rotation and that longer ligands have higher activation energies and show smaller opening angles of precession due to stronger ligand-ligand interactions. Generally, this work provides insight into the arrangement and dynamics of ligands in nanocrystal solids, which is key to understanding their mechanical and thermal properties, and, more generally, highlights the potential of QENS for studying ligand behavior.
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Affiliation(s)
- Maximilian Jansen
- Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Fanni Juranyi
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Olesya Yarema
- Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Tilo Seydel
- Institut Laue-Langevin (ILL), 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Vanessa Wood
- Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
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18
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Calcabrini M, Van den Eynden D, Ribot SS, Pokratath R, Llorca J, De Roo J, Ibáñez M. Ligand Conversion in Nanocrystal Synthesis: The Oxidation of Alkylamines to Fatty Acids by Nitrate. JACS AU 2021; 1:1898-1903. [PMID: 35574040 PMCID: PMC8611721 DOI: 10.1021/jacsau.1c00349] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 05/13/2023]
Abstract
Ligands are a fundamental part of nanocrystals. They control and direct nanocrystal syntheses and provide colloidal stability. Bound ligands also affect the nanocrystals' chemical reactivity and electronic structure. Surface chemistry is thus crucial to understand nanocrystal properties and functionality. Here, we investigate the synthesis of metal oxide nanocrystals (CeO2-x , ZnO, and NiO) from metal nitrate precursors, in the presence of oleylamine ligands. Surprisingly, the nanocrystals are capped exclusively with a fatty acid instead of oleylamine. Analysis of the reaction mixtures with nuclear magnetic resonance spectroscopy revealed several reaction byproducts and intermediates that are common to the decomposition of Ce, Zn, Ni, and Zr nitrate precursors. Our evidence supports the oxidation of alkylamine and formation of a carboxylic acid, thus unraveling this counterintuitive surface chemistry.
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Affiliation(s)
| | | | | | - Rohan Pokratath
- Department
of Chemistry, University of Basel, 4058 Basel, Switzerland
| | - Jordi Llorca
- Institute
of Energy Technologies, Department of Chemical Engineering and Barcelona
Research Center in Multiscale Science and Engineering, Universitat Politecnica de Catalunya, 08019 Barcelona, Spain
| | - Jonathan De Roo
- Department
of Chemistry, University of Basel, 4058 Basel, Switzerland
| | - Maria Ibáñez
- IST
Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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19
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Karpov ON, Bondarenko GN, Merekalov AS, Shandryuk GA, Zhigalina OM, Khmelenin DN, Skryleva EA, Golovan LA, Talroze RV. Formation of the Inorganic and Organic Shells on the Surface of CdSe Quantum Dots. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36190-36200. [PMID: 34286582 DOI: 10.1021/acsami.1c10315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Embedding quantum dots (QDs) into an organic matrix of controllable order requires the identification of their structural characteristics. This analysis is necessary for the creation of anisotropic composites that are sensitive to external stimuli. We have studied the QD structures formed during the single-step synthesis of CdSe/ZnS QDs and their transformations after the initial ligand's substitution for another ligand. This single-step process leads to the formation of the core/shell structure. We detect the presence of two oleic acid residues ionically connected to Zn and Cd. At the same time, the amount of Cd oleate at the surface is very small. We observe the ligand exchange process at the surface of the core/shell QDs. The oleic acid residues are substituted by terphenyl-containing (TERPh-COOH) aromatic acid residues. The reaction between CdSe/ZnS carrying TOP and oleic acid residues ionically bound with QDs and terphenyl-containing acid leads to the coexistence of multiple ligands on the QD surface at a ratio of 11:6:33 for TOP/OA/TERPh-COOH.
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Affiliation(s)
- Oleg N Karpov
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Galina N Bondarenko
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Alexey S Merekalov
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Georgiy A Shandryuk
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Olga M Zhigalina
- Shubnikov Institute of Crystallography, Federal Research Center "Crystallography and Photonics", Russian Academy of Sciences, Moscow 119333, Russia
- Bauman Moscow State Technical University, Moscow 105005, Russia
| | - Dmitriy N Khmelenin
- Shubnikov Institute of Crystallography, Federal Research Center "Crystallography and Photonics", Russian Academy of Sciences, Moscow 119333, Russia
| | - Elena A Skryleva
- National University of Science and Technology MISIS, Leninsky pr. 4, Moscow 119049, Russia
| | - Leonid A Golovan
- Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russia
| | - Raisa V Talroze
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
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20
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Calvin JJ, O'Brien EA, Sedlak AB, Balan AD, Alivisatos AP. Thermodynamics of Composition Dependent Ligand Exchange on the Surfaces of Colloidal Indium Phosphide Quantum Dots. ACS NANO 2021; 15:1407-1420. [PMID: 33404231 DOI: 10.1021/acsnano.0c08683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Quantum dot surfaces can have a substantial effect on their physical, chemical, and optoelectronic properties. When the chemistry that occurs at the surface of nanocrystals is studied, critical insights can be gained into the fundamental structural, thermodynamic, and optical properties of quantum dot materials providing a valuable guide for how to best adapt them for desired applications. Colloidal quantum dots are often terminated with organic ligands that consist of a long aliphatic chain and a head group that binds tightly to the nanocrystal surface. While extensive work has been done to understand how ligand head groups influence quantum dot properties, studies to unravel the influence of the organic ligand tail on ligands and surface reaction equilibria are incomplete. To further investigate the driving forces of quantum dot surface modification, a series of ligand exchange reactions with oleic acid were performed on indium phosphide quantum dots, initially terminated with straight-chain carboxylates of variable lengths. The reaction was monitored using isothermal titration calorimetry and 1H NMR to determine the extent of each reaction and its associated thermodynamics. From these measurements, interligand interactions were observed to be dependent on the length of the straight-chain ligand. A modified Ising model was used to investigate the enthalpic and entropic effects contributing to these ligand exchanges and reveal that interligand interactions play a much larger role than previously thought. Additional experimentation with phosphonic acid ligand exchange reveals complexity in the reaction mechanism but further illustrates the significant impact of ligand tail group length on thermodynamics, even in cases where there is a large difference in head group binding energy.
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Affiliation(s)
- Jason J Calvin
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Erin A O'Brien
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | | | - Arunima D Balan
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - A Paul Alivisatos
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
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21
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Calvin JJ, Swabeck JK, Sedlak AB, Kim Y, Jang E, Alivisatos AP. Thermodynamic Investigation of Increased Luminescence in Indium Phosphide Quantum Dots by Treatment with Metal Halide Salts. J Am Chem Soc 2020; 142:18897-18906. [PMID: 33095575 DOI: 10.1021/jacs.0c08954] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Increasing the quantum yields of InP quantum dots is important for their applications, particularly for use in consumer displays. While several methods exist to improve quantum yield, the addition of inorganic metal halide salts has proven promising. To further investigate this phenomenon, InP quantum dots dispersed in tetrahydrofuran were titrated with ZnCl2, ZnBr2, and InCl3. The optical properties were observed, and the reactions were studied by using quantitative 1H NMR and thermodynamic measurements from isothermal titration calorimetry. These measurements contradict the previously hypothesized reaction mechanism in which metal halide salts, acting as Z-type ligands, passivate undercoordinated anions on the surface of the quantum dots. This work provides evidence for a newly proposed mechanism wherein the metal halide salts undergo a ligand exchange with indium myristate. Thermodynamic measurements prove key to supporting this new mechanism, particularly in describing the organic ligand interactions on the surface. An Ising model was used to simulate the quantum dot surface and was fit by using thermodynamic and 1H NMR data. Together, these data and the proposed exchange mechanism provide greater insight into the surface chemistry of quantum dots.
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Affiliation(s)
- Jason J Calvin
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Joseph K Swabeck
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | | | - Yongwook Kim
- Inorganic Material Lab, Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Eunjoo Jang
- Inorganic Material Lab, Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - A Paul Alivisatos
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
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