1
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Calvin JJ, Sedlak AB, Brewer AS, Kaufman TM, Alivisatos AP. Evidence and Structural Insights into a Ligand-Mediated Phase Transition in the Solvated Ligand Shell of Quantum Dots. ACS NANO 2024; 18:25257-25270. [PMID: 39186512 DOI: 10.1021/acsnano.4c08439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
As synthesized, nanocrystal surfaces are typically covered in coordinating organic ligands, and the degree of packing and order of these ligands are ongoing questions in the field of colloidal nanocrystals, particularly in the solution state. Recently, isothermal titration calorimetry coupled with 1H NMR has been used to probe ligand exchanges on colloidal quantum dots, revealing the importance of the composition of the ligand shell on exchange thermodynamics. Previous work has shown that the geometry and length of a ligand's aliphatic chain can influence the thermodynamics of exchange. This has been attributed to interligand interactions, and the use of a modified Ising model simulation to account for these collective effects has been critical in describing these reactions. In this report, we explore the reaction between indium phosphide quantum dots and zinc chloride on a size series of nanocrystals capped with two different lengths of aliphatic, straight-chain carboxylate ligands to investigate the effect that nanocrystal size has on these interligand interactions. We demonstrate that interligand interactions increase as the nanocrystal size increases, changing the thermodynamics of the ligand exchange reaction. Critically, we show that a self-consistent model of these ligand exchanges does not fit the data without the use of a phase transition term in the model and that the strength of this phase transition depends on the nanocrystal size. Combined with solution state X-ray diffraction, these results provide indirect evidence that ligands are ordered on nanocrystals in the solution state.
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Affiliation(s)
- Jason J Calvin
- Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | | | - Amanda S Brewer
- 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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2
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Chabeda D, Gee S, Rabani E. Ligand-Induced Size-Dependent Circular Dichroism in Quantum Dots. J Phys Chem Lett 2024:7863-7869. [PMID: 39052989 DOI: 10.1021/acs.jpclett.4c01682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Recent experiments have probed the chiral properties of semiconductor nanocrystal (NC) quantum dots (QDs), but understanding the circular dichroism line shape, excitonic features, and chirality induction mechanism remains a challenge. We propose an atomistic pseudopotential method to model chiral ligand passivated QDs, computing circular dichroism (CD) spectra for CdSe QDs (2.6-3.8 nm). We find strong agreement between calculated and measured line shapes, predicting consistent bisignate line shapes with decreasing CD magnitude as size increases. Our analysis reveals the origin of bisignate line shapes, arising from nondegenerate excitons with opposing angular momenta. We also explore the impact of chiral ligand orientation on QD surfaces, observing changes in the optical activity magnitude and sign. This orientation sensitivity offers the means to distinguish ordered from disordered ligand configurations, facilitating the study of order-disorder transitions at ligand-QD interfaces.
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Affiliation(s)
- Daniel Chabeda
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Stephen Gee
- Department of Materials, University of California, Santa Barbara, Santa Barbara, California 93106-5050, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv, Israel 69978
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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3
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Knapp TV, Hasan MR, Niebuur BJ, Widmer-Cooper A, Kraus T. Stabilization of Apolar Nanoparticle Dispersions by Molecular Additives. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13527-13537. [PMID: 38889250 DOI: 10.1021/acs.langmuir.4c00996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
We study the effect of additives on the colloidal stability of alkanethiol-coated gold nanoparticles. Cyclic amines and sulfides of different sizes were added to dispersions in decane at additive concentrations below 128 mM. Small-angle X-ray scattering (SAXS) indicated that tetrahydrothiophene reduced the agglomeration temperature, Tagglo, by up to 29 °C, a considerable increase in colloidal stability. Amines had a much weaker stabilizing effect of up to 2.5 °C. We found an unexpected maximum of stabilization for low additive concentrations, where Tagglo increased at concentrations above 64 mM. Molecular dynamics simulations were used to correlate these observations with the ligand shell structure. They excluded the physisorption of additives as a stabilization mechanism and suggested that sulfides replace hexadecanethiol on the AuNP surfaces by chemisorption. This hinders ligand ordering, thereby reducing Tagglo, which explains the stabilizing effect. Clustering of chemisorbed additive molecules at high concentration restabilized the ligand ordered state, explaining the detrimental effect of higher additive concentrations. The predictions of the simulations were confirmed by using thermogravimetric analyses and SAXS measurements of washed samples that indicated that the structure of the ligand shell itself, not the presence of physisorbed additives, changes Tagglo. Finally, we calculated potentials of mean force, which show that larger sulfide-based additives have a weaker affinity for the gold surface than smaller ones due to stronger steric hindrance. This explains why smaller cyclic sulfides were the most efficient stabilizers.
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Affiliation(s)
| | - Mohammad Rashedul Hasan
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Bart-Jan Niebuur
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Asaph Widmer-Cooper
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia
| | - Tobias Kraus
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
- Saarland University, Colloid and Interface Chemistry, Campus D2 2, 66123 Saarbrücken, Germany
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4
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Pang E, Li X, Zhao S, Tang Y, Xing X, Wang Q, Yang K, Wang B, Jin S, Song X, Lan M. Calcium-enriched carbon nanoparticles loaded with indocyanine green for near-infrared fluorescence imaging-guided synergistic calcium overload, photothermal therapy, and glutathione-depletion-enhanced photodynamic therapy. J Mater Chem B 2024; 12:1846-1853. [PMID: 38284427 DOI: 10.1039/d3tb02690f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Combining phototherapy with other treatments has significantly advanced cancer therapy. Here, we designed and fabricated calcium-enriched carbon nanoparticles (Ca-CNPs) that could effectively deplete glutathione (GSH) and release calcium ions in tumors, thereby enhancing the efficacy of photodynamic therapy (PDT) and the calcium overload effect that leads to mitochondrial dysfunction. Due to the electrostatic interaction, π-π stacking interaction, multiple hydrogen bonds, and microporous structures, indocyanine green (ICG) was loaded onto the surface of Ca-CNPs with a high loading efficiency of 44.7 wt%. The obtained Ca-CNPs@ICG can effectively improve the photostability of ICG while retaining its ability to generate singlet oxygen (1O2) and undergo photothermal conversion (Ca-CNPs@ICG vs. ICG, 45.1% vs. 39.5%). In vitro and in vivo experiments demonstrated that Ca-CNPs@ICG could be used for near-infrared fluorescence imaging-guided synergistic calcium overload, photothermal therapy, and GSH depletion-enhanced PDT. This study sheds light on the improvement of 1O2 utilization efficiency and calcium overload-induced mitochondrial membrane potential imbalance in tumor cells.
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Affiliation(s)
- E Pang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Xiangcao Li
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Shaojing Zhao
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Yuanyu Tang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Xuejian Xing
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Qin Wang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Ke Yang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Benhua Wang
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Shiguang Jin
- Center for Translational Medicine, The Affiliated Taizhou People's Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu, 225300, P. R. China
| | - Xiangzhi Song
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
| | - Minhuan Lan
- Hunan Provincial Key Laboratory of Micro & Nano Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, P. R. China.
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5
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Zuri S, Shapiro A, Kronik L, Lifshitz E. Uncovering Multiple Intrinsic Chiral Phases in (PEA) 2PbI 4 Halide Perovskites. J Phys Chem Lett 2023:4901-4907. [PMID: 37200134 DOI: 10.1021/acs.jpclett.3c00685] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Two-dimensional (2D) halide perovskites offer a unique platform for investigating the ground state of materials possessing significant anharmonicity. In contrast to three-dimensional perovskites, their 2D counterparts offer substantially fewer degrees of freedom, resulting in multiple well-defined crystal structures. In this work, we thoroughly investigate the anharmonic ground state of the benchmark (PEA)2PbI4 compound, using complementary information from low-temperature X-ray diffraction (XRD) and photoluminescence spectroscopy, supported by density functional theory calculations. We extrapolate four crystallographic configurations from low-temperature XRD. These configurations imply that the ground state has an intrinsic disorder stemming from two coexisting chiral sublattices, each with a bioriented organic spacer molecule. We further show evidence that these chiral structures form unevenly populated ground states, portraying uneven anharmonicity, where the state population may be tuned by surface effects. Our results uncover a disordered ground state that may induce intrinsic grain boundaries, which cannot be ignored in practical applications.
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Affiliation(s)
- Shahar Zuri
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Helen Diller Quantum Information Center and the Grand Technion Energy Program, Technion, Haifa 3200003, Israel
| | - Arthur Shapiro
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Helen Diller Quantum Information Center and the Grand Technion Energy Program, Technion, Haifa 3200003, Israel
| | - Leeor Kronik
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth 76100, Israel
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Helen Diller Quantum Information Center and the Grand Technion Energy Program, Technion, Haifa 3200003, Israel
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6
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Sudo T, Yamashita S, Koike N, Kamiya H, Okada Y. Dispersibility of TiO 2 Nanoparticles in Less Polar Solvents: Role of Ligand Tail Structures. Chemistry 2023; 29:e202203608. [PMID: 36575960 DOI: 10.1002/chem.202203608] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 12/18/2022] [Accepted: 12/28/2022] [Indexed: 12/29/2022]
Abstract
Nanoparticles (NPs) are inherently prone to aggregation and loss of their size-derived properties, thus it is essential to enhance their dispersibility for applications. In less polar solvents, organic ligands containing oleyl groups are known as good dispersants due to their inefficient shell packing and inhibition of chain-chain crystallization as well as interdigitation between adjacent NPs. However, reagents with oleyl structures, such as oleic acid and oleylamine, can contain trans double bonds and saturated impurities, which might affect the chemical and/or physical properties of the NPs. Nevertheless, the effect of slight differences in surface ligand structure, including isomers, on the dispersibility of NPs has been little studied. We have synthesized five phosphonic acid ligands to investigate the structure-dispersibility relationship in detail. Dynamic light scattering and visible light transmittance revealed that not only regio- but also the stereochemistries of the C=C double bond in the ligand molecule, as well as the choice of solvent, are key factors in enhancing dispersibility.
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Affiliation(s)
- Tatsuya Sudo
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Shohei Yamashita
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Natsumi Koike
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Hidehiro Kamiya
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Yohei Okada
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
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7
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Yamashita S, Sudo T, Kamiya H, Okada Y. Colloidal Stability of TiO
2
Nanoparticles: The Roles of Phosphonate Ligand Length and Solution Temperature. Chemistry 2022; 28:e202201560. [DOI: 10.1002/chem.202201560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Shohei Yamashita
- Department of Chemical Engineering Tokyo University of Agriculture and Technology 2-24-16 Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Tatsuya Sudo
- Department of Chemical Engineering Tokyo University of Agriculture and Technology 2-24-16 Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Hidehiro Kamiya
- Department of Chemical Engineering Tokyo University of Agriculture and Technology 2-24-16 Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Yohei Okada
- Department of Applied Biological Science Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho, Fuchu Tokyo 183-8509 Japan
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8
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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: 12] [Impact Index Per Article: 6.0] [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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9
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Guillemeney L, Lermusiaux L, Landaburu G, Wagnon B, Abécassis B. Curvature and self-assembly of semi-conducting nanoplatelets. Commun Chem 2022; 5:7. [PMID: 36697722 PMCID: PMC9814859 DOI: 10.1038/s42004-021-00621-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/21/2021] [Indexed: 01/28/2023] Open
Abstract
Semi-conducting nanoplatelets are two-dimensional nanoparticles whose thickness is in the nanometer range and controlled at the atomic level. They have come up as a new category of nanomaterial with promising optical properties due to the efficient confinement of the exciton in the thickness direction. In this perspective, we first describe the various conformations of these 2D nanoparticles which display a variety of bent and curved geometries and present experimental evidences linking their curvature to the ligand-induced surface stress. We then focus on the assembly of nanoplatelets into superlattices to harness the particularly efficient energy transfer between them, and discuss different approaches that allow for directional control and positioning in large scale assemblies. We emphasize on the fundamental aspects of the assembly at the colloidal scale in which ligand-induced forces and kinetic effects play a dominant role. Finally, we highlight the collective properties that can be studied when a fine control over the assembly of nanoplatelets is achieved.
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Affiliation(s)
- Lilian Guillemeney
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Laurent Lermusiaux
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Guillaume Landaburu
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benoit Wagnon
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benjamin Abécassis
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
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10
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Liu G, Liang W, Xue X, Rosei F, Wang Y. Atomic Identification of Interfaces in Individual Core@shell Quantum Dots. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2102784. [PMID: 34647434 PMCID: PMC8596122 DOI: 10.1002/advs.202102784] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/22/2021] [Indexed: 05/29/2023]
Abstract
CdSe@CdS Core@shell quantum dots (QDs) have been widely studied in recent years, due to their architecture which allows to tailor properties by controlling structure and composition. However, since CdSe and CdS have the same crystal structure, same cations, and similar lattice parameters, it is very challenging to image the interface. Herein, high-resolution transmission electron microscopy, high-angle annular dark-field imaging, and energy-dispersive X-ray spectroscopy elemental mapping are combined to characterize the core@shell structure and identify the interface in the CdSe@CdS QDs with different CdS shell thicknesses. By examining changes in lattice spacing in an individual CdSe@CdS quantum dot, the atomic core@shell interface is identified. For thin-shelled QDs, an ideal coherent interface forms between core and shell due to the small lattice mismatch, and the lattice spacing remains unchanged at the core and shell regions. For thick-shelled QDs, the lattice spacing is different at the core and shell regions, while the heterostructured interface is still coherent and cannot be clearly imaged. As the shell thickness further increases, a sharp core@shell interface appears. The results define an approach to characterize the heterostructure of two materials with the same crystalline structure and cations.
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Affiliation(s)
- Guiju Liu
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Wenshuang Liang
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Xuyan Xue
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
| | - Federico Rosei
- Centre Énergie Matériaux et TélécommunicationsInstitut National de la Recherche Scientifique1650 Boulevard Lionel‐BouletVarennesQuébecJ3X 1S2Canada
| | - Yiqian Wang
- College of Physics & State Key LaboratoryQingdao UniversityNo. 308 Ningxia RoadQingdao266071P. R. China
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11
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Lang EN, Porter AG, Ouyang T, Shi A, Hayes TR, Davis TC, Claridge SA. Oleylamine Impurities Regulate Temperature-Dependent Hierarchical Assembly of Ultranarrow Gold Nanowires on Biotemplated Interfaces. ACS NANO 2021; 15:10275-10285. [PMID: 33998802 DOI: 10.1021/acsnano.1c02414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nanocrystals are often synthesized using technical grade reagents such as oleylamine (OLAm), which contains a blend of 9-cis-octadeceneamine with trans-unsaturated and saturated amines. Here, we show that gold nanowires (AuNWs) synthesized with OLAm ligands undergo thermal transitions in interfacial assembly (ribbon vs. nematic); transition temperatures vary widely with the batch of OLAm used for synthesis. Mass spectra reveal that higher-temperature AuNW assembly transitions are correlated with an increased abundance of trans and saturated chains in certain blends. DSC thermograms show that both pure (synthesized) and technical-grade OLAm have primary melting transitions near -5 °C (20-30 °C lower than the literature melting temperature range of OLAm). A second, broader melting transition (in the previous reported melting range) appears in technical grade blends; its temperature varies with the abundance of trans and saturated chains. Our findings illustrate that, similar to biological membranes, blends of alkyl chains can be used to generate mesoscopic hierarchical nanocrystal assembly, particularly at interfaces that further modulate transition temperatures.
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Affiliation(s)
- Erin N Lang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ashlin G Porter
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tianhong Ouyang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Anni Shi
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tyler R Hayes
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tyson C Davis
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Shelley A Claridge
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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12
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Observation of ordered organic capping ligands on semiconducting quantum dots via powder X-ray diffraction. Nat Commun 2021; 12:2663. [PMID: 33976186 PMCID: PMC8113276 DOI: 10.1038/s41467-021-22947-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/30/2021] [Indexed: 02/03/2023] Open
Abstract
Powder X-ray diffraction is one of the key techniques used to characterize the inorganic structure of colloidal nanocrystals. The comparatively low scattering factor of nuclei of the organic capping ligands and their propensity to be disordered has led investigators to typically consider them effectively invisible to this technique. In this report, we demonstrate that a commonly observed powder X-ray diffraction peak around [Formula: see text] observed in many small, colloidal quantum dots can be assigned to well-ordered aliphatic ligands bound to and capping the nanocrystals. This conclusion differs from a variety of explanations ascribed by previous sources, the majority of which propose an excess of organic material. Additionally, we demonstrate that the observed ligand peak is a sensitive probe of ligand shell ordering. Changes as a function of ligand length, geometry, and temperature can all be readily observed by X-ray diffraction and manipulated to achieve desired outcomes for the final colloidal system.
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13
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Appel C, Kuttich B, Kraus T, Stühn B. In situ investigation of temperature induced agglomeration in non-polar magnetic nanoparticle dispersions by small angle X-ray scattering. NANOSCALE 2021; 13:6916-6920. [PMID: 33885492 DOI: 10.1039/d0nr08434d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Non-polar magnetic nanoparticles agglomerate upon cooling. This process is followed by in situ small angle X-ray scattering to assess structural properties of the emerging agglomerates. On the length scale of a few particle diameters, no differences are found between the agglomerates of small (d = 12 nm) and large (d = 22 nm) nanoparticles. Hard-sphere like random packing with a local packing fraction of η = 0.4 is seen. On larger length scales, small particles form compact superstructures, while large particles arrange into agglomerates that resemble chain-like structures in SAXS. This can be explained by directed magnetic dipole interactions that dominate larger particles, while isotropic van der Waals interaction governs the agglomeration of smaller particles.
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Affiliation(s)
- Christian Appel
- Experimental Condensed Matter Physics, TU Darmstadt, Germany
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14
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Yan C, Weinberg D, Jasrasaria D, Kolaczkowski MA, Liu ZJ, Philbin JP, Balan AD, Liu Y, Schwartzberg AM, Rabani E, Alivisatos AP. Uncovering the Role of Hole Traps in Promoting Hole Transfer from Multiexcitonic Quantum Dots to Molecular Acceptors. ACS NANO 2021; 15:2281-2291. [PMID: 33336575 DOI: 10.1021/acsnano.0c08158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding electronic dynamics in multiexcitonic quantum dots (QDs) is important for designing efficient systems useful in high power scenarios, such as solar concentrators and multielectron charge transfer. The multiple charge carriers within a QD can undergo undesired Auger recombination events, which rapidly annihilate carriers on picosecond time scales and generate heat from absorbed photons instead of useful work. Compared to the transfer of multiple electrons, the transfer of multiple holes has proven to be more difficult due to slower hole transfer rates. To probe the competition between Auger recombination and hole transfer in CdSe, CdS, and CdSe/CdS QDs of varying sizes, we synthesized a phenothiazine derivative with optimized functionalities for binding to QDs as a hole accepting ligand and for spectroscopic observation of hole transfer. Transient absorption spectroscopy was used to monitor the photoinduced absorption features from both trapped holes and oxidized ligands under excitation fluences where the averaged initial number of excitons in a QD ranged from ∼1 to 19. We observed fluence-dependent hole transfer kinetics that last around 100 ps longer than the predicted Auger recombination lifetimes, and the transfer of up to 3 holes per QD. Theoretical modeling of the kinetics suggests that binding of hole acceptors introduces trapping states significantly different from those in native QDs passivated with oleate ligands. Holes in these modified trap states have prolonged lifetimes, which promotes the hole transfer efficiency. These results highlight the beneficial role of hole-trapping states in devising hole transfer pathways in QD-based systems under multiexcitonic conditions.
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Affiliation(s)
- Chang Yan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Matthew A Kolaczkowski
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zi-Jie Liu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - John P Philbin
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Arunima D Balan
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Yi Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - A Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
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15
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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: 14] [Impact Index Per Article: 4.7] [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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16
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Elbert KC, Taheri MM, Gogotsi N, Park J, Baxter JB, Murray CB. Electron accepting naphthalene bisimide ligand architectures for modulation of π-π stacking in nanocrystal hybrid materials. NANOSCALE HORIZONS 2020; 5:1509-1514. [PMID: 33103695 DOI: 10.1039/d0nh00359j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Investigation of charge transfer in quantum dot (QD) systems is an area of great interest. Specifically, the relationship between capping ligand and rate of charge transfer has been studied as a means to optimize these materials. To investigate the role of ligand interaction on the QD surface for electron transfer, we designed and synthesized a series of ligands containing an electron accepting moiety, naphthalene bisimide (NBI). These ligands differ in their steric bulk: as one allows for π-π stacking between the NBI moieties at high surface coverages, while the other does not, allowing for a direct comparison of these effects. Once grafted onto QDs, these hybrid materials were studied using UV-Vis, fluorescence, and transient absorption spectroscopy. Interestingly, the sample with the fastest electron transfer was not the sample with the most NBI π-π stacking, it was instead where these ligands were mixed amongst oleic acid, breaking up H-aggregates between the NBI groups.
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Affiliation(s)
- Katherine C Elbert
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
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17
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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: 29] [Impact Index Per Article: 7.3] [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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18
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Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods. Catalysts 2020. [DOI: 10.3390/catal10101143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this study, the impact of the type of ligand at the surface of colloidal CdSe@CdS dot-in-rod nanostructures on the basic exciton relaxation and charge localization processes is closely examined. These systems have been introduced into the field of artificial photosynthesis as potent photosensitizers in assemblies for light driven hydrogen generation. Following photoinduced exciton generation, electrons can be transferred to catalytic reaction centers while holes localize into the CdSe seed, which can prevent charge recombination and lead to the formation of long-lived charge separation in assemblies containing catalytic reaction centers. These processes are in competition with trapping processes of charges at surface defect sites. The density and type of surface defects strongly depend on the type of ligand used. Here we report on a systematic steady-state and time-resolved spectroscopic investigation of the impact of the type of anchoring group (phosphine oxide, thiols, dithiols, amines) and the bulkiness of the ligand (alkyl chains vs. poly(ethylene glycol) (PEG)) to unravel trapping pathways and localization efficiencies. We show that the introduction of the widely used thiol ligands leads to an increase of hole traps at the surface compared to trioctylphosphine oxide (TOPO) capped rods, which prevent hole localization in the CdSe core. On the other hand, steric restrictions, e.g., in dithiolates or with bulky side chains (PEG), decrease the surface coverage, and increase the density of electron trap states, impacting the recombination dynamics at the ns timescale. The amines in poly(ethylene imine) (PEI) on the other hand can saturate and remove surface traps to a wide extent. Implications for catalysis are discussed.
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19
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Elimelech O, Aviv O, Oded M, Banin U. A Tale of Tails: Thermodynamics of CdSe Nanocrystal Surface Ligand Exchange. NANO LETTERS 2020; 20:6396-6403. [PMID: 32787157 DOI: 10.1021/acs.nanolett.0c01913] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The surface ligands of semiconductor nanocrystals (NCs) are central for determining their properties and for their flexible implementation in diverse applications. Thus far, the thermodynamic characteristics of ligand exchange reactions were attained by indirect methods. Isothermal titration calorimetry is utilized to directly and independently measure both the equilibrium constant and the reaction enthalpy of a model ligand exchange reaction from oleate-capped CdSe NCs to a series of alkylthiols. Increased reaction exothermicity for longer chains, accompanied by a decrease in reaction entropy with an overall enthalpy-entropy compensation behavior is observed, explained by the length-dependent interchain interactions and the organization of the bound ligands on the NCs' surface. An increase in the spontaneity of the reaction with decreasing NC size is also revealed, due to their enhanced surface reactivity. This work provides a fundamental understanding of the physicochemical properties of the NC surface with implications for NC surface ligand design.
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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
| | - 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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20
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Hao J, Li Y, Miao J, Liu R, Li J, Liu H, Wang Q, Liu H, Delville MH, He T, Wang K, Zhu X, Cheng J. Ligand-Induced Chirality in Asymmetric CdSe/CdS Nanostructures: A Close Look at Chiral Tadpoles. ACS NANO 2020; 14:10346-10358. [PMID: 32806030 DOI: 10.1021/acsnano.0c03909] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ligand-induced chirality in asymmetric CdSe/CdS core-shell nanocrystals (NCs) has been extensively applied in chiral biosensors, regioselective syntheses and assemblies, circularly polarized luminescence (CPL), and chiroptic-based devices due to their excellent physiochemical properties, such as the tunable quantum confinement effects, surface functionality, and chemical stability. Herein, we present CdSe/CdS NCs with various morphologies such as nanoflowers, tadpoles, and dot/rods (DRs) with chirality induced by surface chiral ligands. The observed circular dichroism (CD) and CPL activities are closely associated with the geometrical characteristics of the nanostructures, such as the shell thickness and the aspect ratio of the CdSe/CdS NCs. Furthermore, in situ observations of the growth of tadpoles with a single tail indicate that the CD response is mainly attributed to the CdS shell, which has a maximum tail length of ∼45 nm (approximately λ/10 of the incident light wavelength). On the other hand, the CPL activity is only related to the CdSe core, and the activity benefits from a thin CdS shell with a relatively high photoluminescence quantum yield (QY). Further theoretical models demonstrated the aspect-ratio-dependent g-factor and QY variations in these asymmetric nanostructures. These findings provide insights into not only the asymmetric synthesis of CdSe/CdS NCs, but also the rational design of CdSe/CdS nanostructures with tunable CD and CPL activities.
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Affiliation(s)
- Junjie Hao
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- CNRS, Univ. Bordeaux, Bordeaux INP, ICMCB, UMR 5026, Pessac F-33608, France
| | - Yiwen Li
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jun Miao
- Institute of Energy and Climate Research (IEK) Photovoltaics, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Rulin Liu
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Jiagen Li
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Haochen Liu
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qiushi Wang
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
| | - Huan Liu
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | | | - Tingchao He
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Kai Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xi Zhu
- Shenzhen Institute of Artificial Intelligence and Robotics for Society (AIRS), Shenzhen, Guangdong 518172, China
| | - Jiaji Cheng
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
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21
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Yang W, Vansuch GE, Liu Y, Jin T, Liu Q, Ge A, Sanchez MLK, K Haja D, Adams MWW, Dyer RB, Lian T. Surface-Ligand "Liquid" to "Crystalline" Phase Transition Modulates the Solar H 2 Production Quantum Efficiency of CdS Nanorod/Mediator/Hydrogenase Assemblies. ACS APPLIED MATERIALS & INTERFACES 2020; 12:35614-35625. [PMID: 32662974 DOI: 10.1021/acsami.0c07820] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This study reports how the length of capping ligands on a nanocrystal surface affects its interfacial electron transfer (ET) with surrounding molecular electron acceptors, and consequently, impact the H2 production of a biotic-abiotic hybrid artificial photosynthetic system. Specifically, we study how the H2 production efficiency of a hybrid system, combining CdS nanorods (NRs), [NiFe] hydrogenase, and redox mediators (propyl-bridged 2,2'-bipyridinium, PDQ2+), depends on the alkyl chain length of mercaptocarboxylate ligands on the NR surface. We observe a minor decrease of the quantum yield for H2 production from 54 ± 6 to 43 ± 2% when varying the number of methylene units in the ligands from 2 to 7. In contrast, an abrupt decrease of the yield was observed from 43 ± 2 to 4 ± 1% when further increasing n from 7 to 11. ET studies reveal that the intrinsic ET rates from the NRs to the electron acceptor PDQ2+ are all within 108-109 s-1 regardless of the length of the capping ligands. However, the number of adsorbed PDQ2+ molecules on NR surfaces decreases dramatically when n ≥ 10, with the saturating number changing from 45 ± 5 to 0.3 ± 0.1 for n = 2 and 11, respectively. These results are not consistent with the commonly perceived exponential dependence of ET rates on the ligand length. Instead, they can be explained by the change of the accessibility of NR surfaces to electron acceptors from a disordered "liquid" phase at n < 7 to a more ordered "crystalline" phases at n > ∼7. These results highlight that the order of capping ligands is an important design parameter for further constructing nanocrystal/molecular assemblies in broad nanocrystal-based applications.
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Affiliation(s)
- Wenxing Yang
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
- Department of Chemistry-Ångström Laboratory, Physical Chemistry, Uppsala University, SE-75120 Uppsala, Sweden
| | - Gregory E Vansuch
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Yawei Liu
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Tao Jin
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Qiliang Liu
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Aimin Ge
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Monica L K Sanchez
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Dominik K Haja
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
| | - Michael W W Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United States
| | - R Brian Dyer
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
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22
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Lee H, Yoon DE, Koh S, Kang MS, Lim J, Lee DC. Ligands as a universal molecular toolkit in synthesis and assembly of semiconductor nanocrystals. Chem Sci 2020; 11:2318-2329. [PMID: 32206291 PMCID: PMC7069383 DOI: 10.1039/c9sc05200c] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 02/10/2020] [Indexed: 01/05/2023] Open
Abstract
The multiple ligands with different functionalities enable atomic-precision control of NCs morphology and subtle inter-NC interactions, which paves the way for novel optoelectronic applications.
Successful exploitation of semiconductor nanocrystals (NCs) in commercial products is due to the remarkable progress in the wet-chemical synthesis and controlled assembly of NCs. Central to the cadence of this progress is the ability to understand how NC growth and assembly can be controlled kinetically and thermodynamically. The arrested precipitation strategy offers a wide opportunity for materials selection, size uniformity, and morphology control. In this colloidal approach, capping ligands play an instrumental role in determining growth parameters and inter-NC interactions. The impetus for exquisite control over the size and shape of NCs and orientation of NCs in an ensemble has called for the use of two or more types of ligands in the system. In multiple ligand approaches, ligands with different functionalities confer extended tunability, hinting at the possibility of atomic-precision growth and long-range ordering of desired superlattices. Here, we highlight the progress in understanding the roles of ligands in size and shape control and assembly of NCs. We discuss the implication of the advances in the context of optoelectronic applications.
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Affiliation(s)
- Hyeonjun Lee
- Department of Chemical and Biomolecular Engineering , KAIST Institute for the Nanocentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
| | - Da-Eun Yoon
- Department of Chemical and Biomolecular Engineering , KAIST Institute for the Nanocentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
| | - Sungjun Koh
- Department of Chemical and Biomolecular Engineering , KAIST Institute for the Nanocentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
| | - Moon Sung Kang
- Department of Chemical and Biomolecular Engineering , Sogang University , Seoul 04107 , Republic of Korea
| | - Jaehoon Lim
- Department of Energy Science , Center for Artificial Atoms , Sungkyunkwan University (SKKU) , Suwon , Gyeonggi-do 16419 , Republic of Korea .
| | - Doh C Lee
- Department of Chemical and Biomolecular Engineering , KAIST Institute for the Nanocentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
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