1
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Abécassis B, Greenberg MW, Bal V, McMurtry BM, Campos MP, Guillemeney L, Mahler B, Prevost S, Sharpnack L, Hendricks MP, DeRosha D, Bennett E, Saenz N, Peters B, Owen JS. Persistent nucleation and size dependent attachment kinetics produce monodisperse PbS nanocrystals. Chem Sci 2022; 13:4977-4983. [PMID: 35655873 PMCID: PMC9067564 DOI: 10.1039/d1sc06134h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 03/25/2022] [Indexed: 01/03/2023] Open
Abstract
Modern syntheses of colloidal nanocrystals yield extraordinarily narrow size distributions that are believed to result from a rapid "burst of nucleation" (La Mer, JACS, 1950, 72(11), 4847-4854) followed by diffusion limited growth and size distribution focusing (Reiss, J. Chem. Phys., 1951, 19, 482). Using a combination of in situ X-ray scattering, optical absorption, and 13C nuclear magnetic resonance (NMR) spectroscopy, we monitor the kinetics of PbS solute generation, nucleation, and crystal growth from three thiourea precursors whose conversion reactivity spans a 2-fold range. In all three cases, nucleation is found to be slow and continues during >50% of the precipitation. A population balance model based on a size dependent growth law (1/r) fits the data with a single growth rate constant (k G) across all three precursors. However, the magnitude of the k G and the lack of solvent viscosity dependence indicates that the rate limiting step is not diffusion from solution to the nanoparticle surface. Several surface reaction limited mechanisms and a ligand penetration model that fits data our experiments using a single fit parameter are proposed to explain the results.
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Affiliation(s)
- Benjamin Abécassis
- Laboratoire de Chimie, ENS de Lyon, CNRS, Université Claude Bernard Lyon 1 F69342 Lyon France
| | | | - Vivekananda Bal
- Department of Chemical Engineering, University of Illinois Urbana-Champaign Illinois 10027 USA
| | - Brandon M McMurtry
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Michael P Campos
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Lilian Guillemeney
- Laboratoire de Chimie, ENS de Lyon, CNRS, Université Claude Bernard Lyon 1 F69342 Lyon France
| | - Benoit Mahler
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière F-69622 Villeurbanne France
| | - Sylvain Prevost
- Institut Laue-Langevin 71 Avenue des Martyrs 38042 Grenoble France
| | - Lewis Sharpnack
- Department of Earth Science, University of California Santa Barbara CA 93106 USA
| | - Mark P Hendricks
- Department of Chemistry, Columbia University New York New York 10027 USA
- Department of Chemistry, Whitman College Walla Walla WA 99362 USA
| | - Daniel DeRosha
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Ellie Bennett
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Natalie Saenz
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Baron Peters
- Department of Chemical Engineering, University of Illinois Urbana-Champaign Illinois 10027 USA
| | - Jonathan S Owen
- Department of Chemistry, Columbia University New York New York 10027 USA
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2
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Campos MP, De Roo J, Greenberg MW, McMurtry BM, Hendricks MP, Bennett E, Saenz N, Sfeir MY, Abécassis B, Ghose SK, Owen JS. Growth kinetics determine the polydispersity and size of PbS and PbSe nanocrystals. Chem Sci 2022; 13:4555-4565. [PMID: 35656143 PMCID: PMC9019910 DOI: 10.1039/d1sc06098h] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 03/16/2022] [Indexed: 12/13/2022] Open
Abstract
A library of thio- and selenourea derivatives is used to adjust the kinetics of PbE (E = S, Se) nanocrystal formation across a 1000-fold range (kr = 10−1 to 10−4 s−1), at several temperatures (80–120 °C), under a standard set of conditions (Pb : E = 1.2 : 1, [Pb(oleate)2] = 10.8 mM, [chalcogenourea] = 9.0 mM). An induction delay (tind) is observed prior to the onset of nanocrystal absorption during which PbE solute is observed using in situ X-ray total scattering. Density functional theory models fit to the X-ray pair distribution function (PDF) support a Pb2(μ2-S)2(Pb(O2CR)2)2 structure. Absorption spectra of aliquots reveal a continuous increase in the number of nanocrystals over more than half of the total reaction time at low temperatures. A strong correlation between the width of the nucleation phase and reaction temperature is observed that does not correlate with the polydispersity. These findings are antithetical to the critical concentration dependence of nucleation that underpins the La Mer hypothesis and demonstrates that the duration of the nucleation period has a minor influence on the size distribution. The results can be explained by growth kinetics that are size dependent, more rapid at high temperature, and self limiting at low temperatures. Colloidal lead chalcogenide nanocrystals nucleate slowly throughout their synthesis rather than in a burst. There is no correlation between the temporal width of the nucleation phase and the polydispersity.![]()
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Affiliation(s)
- Michael P Campos
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Jonathan De Roo
- Department of Chemistry, Columbia University New York New York 10027 USA .,Department of Chemistry, University of Basel Basel 4058 Switzerland
| | | | - Brandon M McMurtry
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Mark P Hendricks
- Department of Chemistry, Columbia University New York New York 10027 USA .,Department of Chemistry, Whitman College Walla Walla Washington 99362 USA
| | - Ellie Bennett
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Natalie Saenz
- Department of Chemistry, Columbia University New York New York 10027 USA
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory Upton New York 11973 USA.,Photonics Initiative, Advanced Science Research Center, City University of New York New York New York 10031 USA.,Department of Physics, Graduate Center, City University of New York New York New York 10016 USA
| | - Benjamin Abécassis
- ENSL, CNRS, Laboratoire de Chimie UMR 5182 46 allée d'Italie 69364 Lyon France.,Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides 91405 Orsay France
| | - Sanjit K Ghose
- National Synchrotron Light Source II, Brookhaven National Laboratory Brookhaven New York USA
| | - Jonathan S Owen
- Department of Chemistry, Columbia University New York New York 10027 USA
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3
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Hughes SM, Hendricks MP, Mullaugh KM, Anderson ME, Bentley AK, Clar JG, Daly CA, Ellison MD, Feng ZV, Gonzalez-Pech NI, Hamachi LS, Heinecke CL, Keene JD, Maley AM, Munro AM, Njoki PN, Olshansky JH, Plass KE, Riley KR, Sonntag MD, St. Angelo SK, Thompson LB, Tollefson EJ, Toote LE, Wheeler KE. The Primarily Undergraduate Nanomaterials Cooperative: A New Model for Supporting Collaborative Research at Small Institutions on a National Scale. ACS Nanosci Au 2021; 1:6-14. [PMID: 37102118 PMCID: PMC10114623 DOI: 10.1021/acsnanoscienceau.1c00020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The Primarily Undergraduate Nanomaterials Cooperative (PUNC) is an organization for research-active faculty studying nanomaterials at Primarily Undergraduate Institutions (PUIs), where undergraduate teaching and research go hand-in-hand. In this perspective, we outline the differences in maintaining an active research group at a PUI compared to an R1 institution. We also discuss the work of PUNC, which focuses on community building, instrument sharing, and facilitating new collaborations. Currently consisting of 37 members from across the United States, PUNC has created an online community consisting of its Web site (nanocooperative.org), a weekly online summer group meeting program for faculty and students, and a Discord server for informal conversations. Additionally, in-person symposia at ACS conferences and PUNC-specific conferences are planned for the future. It is our hope that in the years to come PUNC will be seen as a model organization for community building and research support at primarily undergraduate institutions.
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Affiliation(s)
- Steven M. Hughes
- Department
of Chemistry, Roanoke College, 221 College Lane, Salem, Virginia 24153, United States
| | - Mark P. Hendricks
- Department
of Chemistry, Whitman College, 345 Boyer Avenue, Walla Walla, Washington 99362, United States
| | - Katherine M. Mullaugh
- Department
of Chemistry and Biochemistry, College of
Charleston, 66 George Street, Charleston, South Carolina 29424, United States
| | - Mary E. Anderson
- Department
of Chemistry, Furman University, 3300 Poinsett Highway, Greenville, South Carolina 29613, United States
| | - Anne K. Bentley
- Department
of Chemistry, Lewis & Clark College, 615 S Palatine Hill Rd, Portland, Oregon 97219, United States
| | - Justin G. Clar
- Department
of Chemistry, Elon University, 2625 Campus Box, Elon, North Carolina 27244, United States
| | - Clyde A. Daly
- Department
of Chemistry, Haverford College, 370 Lancaster Avenue, Haverford, Pennsylvania 19041, United States
| | - Mark D. Ellison
- Department
of Chemistry, Ursinus College, P.O. Box 1000, Collegeville, Pennsylvania 19426, United States
| | - Z. Vivian Feng
- Department
of Chemistry, Augsburg University, 2211 Riverside Avenue, Minneapolis, Minnesota 55454, United States
| | - Natalia I. Gonzalez-Pech
- Department
of Chemistry, Hope College, 35 East 12th Street, Holland, Michigan 49423, United States
| | - Leslie S. Hamachi
- Department
of Chemistry & Biochemistry, California
Polytechnic State University, 1 Grand Avenue, San Luis Obispo, California 93401, United States
| | - Christine L. Heinecke
- Department
of Chemistry & Biochemistry, Loyola
University New Orleans, 6363 St. Charles Avenue, New Orleans, Louisiana 70118, United States
| | - Joseph D. Keene
- Department
of Chemistry, Mercer University, 1501 Mercer University Drive, Macon, Georgia 31207, United States
| | - Adam M. Maley
- Mund-Lagowski
Department of Chemistry and Biochemistry, Bradley University, 1501 W Bradley Avenue, Peoria, Illinois 61625, United
States
| | - Andrea M. Munro
- Department
of Chemistry, Pacific Lutheran University, 12180 Park Avenue, Tacoma, Washington 98447, United States
| | - Peter N. Njoki
- Department
of Chemistry & Biochemistry, Hampton
University, 130 William R. Harvey Way, Hampton, Virginia 23668, United
States
| | - Jacob H. Olshansky
- Department
of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, United States
| | - Katherine E. Plass
- Department
of Chemistry, Franklin & Marshall College, P.O. Box 3003, Lancaster, Pennsylvania 17601, United States
| | - Kathryn R. Riley
- Department
of Chemistry & Biochemistry, Swarthmore
College, 500 College Avenue, Swarthmore, Pennsylvania 19081, United States
| | - Matthew D. Sonntag
- Department
of Chemistry & Biochemistry, Albright
College, P.O. Box 15234, Reading, Pennsylvania 19612, United States
| | - Sarah K. St. Angelo
- Department
of Chemistry, Dickinson College, P.O. Box 1773, Carlisle, Pennsylvania 17013, United States
| | - Lucas B. Thompson
- Department
of Chemistry, Gettysburg College, 300 North Washington Street, Gettysburg, Pennsylvania 17325, United States
| | - Emily J. Tollefson
- Department
of Chemistry, University of Puget Sound, 1500 N Warner Street, Tacoma, Washington 98416, United States
| | - Lauren E. Toote
- Department
of Chemistry & Biochemistry, Elizabethtown
College, 1 Alpha Drive, Elizabethtown, Pennsylvania 17022, United States
| | - Korin E. Wheeler
- Department
of Chemistry & Biochemistry, Santa Clara
University, 500 El Camino Real, Santa Clara, California 95053, United States
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4
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Abstract
Supramolecular assembly of peptide-based monomers into nanostructures offers many promising applications in advanced therapies. In this Tutorial Review, we introduce molecular designs to control the structure and potential biological function of supramolecular assemblies. An emphasis is placed on peptide-based supramolecular nanostructures that are intentionally designed to signal cells, either directly through the incorporation of amino acid sequences that activate receptors or indirectly by recruiting native signals such as growth factors. Additionally, we describe the use and future potential of hierarchical structures, such as single molecules that assemble into nanoscale fibers which then align to form macroscopic strings; the strings can then serve as scaffolds for cell growth, proliferation, and differentiation.
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Affiliation(s)
- Kohei Sato
- Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA.
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5
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Passarelli JV, Fairfield DJ, Sather NA, Hendricks MP, Sai H, Stern CL, Stupp SI. Enhanced Out-of-Plane Conductivity and Photovoltaic Performance in n = 1 Layered Perovskites through Organic Cation Design. J Am Chem Soc 2018; 140:7313-7323. [PMID: 29869499 DOI: 10.1021/jacs.8b03659] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Layered perovskites with the formula (R-NH3)2PbI4 have excellent environmental stability but poor photovoltaic function due to the preferential orientation of the semiconducting layer parallel to the substrate and the typically insulating nature of the R-NH3+ cation. Here, we report a series of these n = 1 layered perovskites with the form (aromatic- O-linker-NH3)2PbI4 where the aromatic moiety is naphthalene, pyrene, or perylene and the linker is ethyl, propyl, or butyl. These materials achieve enhanced conductivity perpendicular to the inorganic layers due to better energy level matching between the inorganic layers and organic galleries. The enhanced conductivity and visible absorption of these materials led to a champion power conversion efficiency of 1.38%, which is the highest value reported for any n = 1 layered perovskite, and it is an order of magnitude higher efficiency than any other n = 1 layered perovskite oriented with layers parallel to the substrate. These findings demonstrate the importance of leveraging the electronic character of the organic cation to improve optoelectronic properties and thus the photovoltaic performance of these chemically stable low n layered perovskites.
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6
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Abstract
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Peptide amphiphiles (PAs) are small molecules
that contain hydrophobic
components covalently conjugated to peptides. In this Account, we
describe recent advances involving PAs that consist of a short peptide sequence linked to an aliphatic tail. The peptide sequence
can be designed to form β-sheets among the amino acids near
the alkyl tail, while the residues farthest from the tail are charged
to promote solubility and in some cases contain a bioactive sequence.
In water, β-sheet formation and hydrophobic collapse of the
aliphatic tails induce assembly of the molecules into supramolecular
one-dimensional nanostructures, commonly high-aspect-ratio cylindrical
or ribbonlike nanofibers. These nanostructures hold significant promise
for biomedical functions due to their ability to display a high density of biological signals on their surface for targeting or to activate pathways,
as well as for biocompatibility and biodegradable nature. Recent
studies have shown that supramolecular systems, such as
PAs, often become kinetically trapped in local minima along their
self-assembly reaction coordinate, not unlike the pathways associated
with protein folding. Furthermore, the assembly pathway can influence
the shape, internal structure, and dimension of nanostructures and
thereby affect their bioactivity. We discuss methods to map the energy
landscape of a PA structure as a function of thermal energy and ionic
strength and vary these parameters to convert between kinetically
trapped and thermodynamically favorable states. We also demonstrate
that the pathway-dependent morphology of the PA assembly can determine
biological cell adhesion and survival rates. The dynamics associated
with the nanostructures are also critical
to their function, and techniques are now available to probe the internal
dynamics of these nanostructures. For example, by conjugating radical
electron spin labels to PAs, electron paramagnetic resonance spectroscopy can be
used to study the rotational diffusion rates within the fiber, showing
a liquidlike to solidlike transition through the cross section of
the nanofiber. PAs can also be labeled with fluorescent dyes, allowing
the use of super-resolution microscopy techniques to study the molecular
exchange dynamics between PA fibers. For a weak hydrogen-bonding PA,
individual PA molecules or clusters exchange between fibers in time
scales as short as minutes. The amount of hydrogen bonding within
PAs that dictates the dynamics also plays an important role in biological
function. In one case, weak hydrogen bonding within a PA resulted
in cell death through disruption of lipid membranes, while in another
example reduced hydrogen bonding enhanced growth factor signaling
by increasing lipid raft mobility. PAs are a promising platform
for designing advanced hybrid materials.
We discuss a covalent polymer with a rigid aromatic imine backbone
and alkylated peptide side chains that simultaneously polymerizes
and interacts with a supramolecular PA structure with identical chemistry
to that of the side chains. The covalent polymerization can be “catalyzed”
by noncovalent polymerization of supramolecular monomers, taking advantage
of the dynamic nature of supramolecular assemblies. These novel hybrid
structures have potential in self-repairing materials and as reusable
scaffolds for delivery of drugs or other chemicals. Finally, we highlight
recent biomedical applications of PAs and related structures, ranging
from bone regeneration to decreasing blood loss during internal bleeding.
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Affiliation(s)
- Mark P. Hendricks
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois 60611, United States
| | - Kohei Sato
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois 60611, United States
| | - Liam C. Palmer
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois 60611, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Samuel I. Stupp
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois 60611, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Medicine, Northwestern University, Chicago, Illinois 60611, United States
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, United States
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7
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Campos MP, Hendricks MP, Beecher AN, Walravens W, Swain RA, Cleveland GT, Hens Z, Sfeir MY, Owen JS. A Library of Selenourea Precursors to PbSe Nanocrystals with Size Distributions near the Homogeneous Limit. J Am Chem Soc 2017; 139:2296-2305. [PMID: 28103035 DOI: 10.1021/jacs.6b11021] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We report a tunable library of N,N,N'-trisubstituted selenourea precursors and their reaction with lead oleate at 60-150 °C to form carboxylate-terminated PbSe nanocrystals in quantitative yields. Single exponential conversion kinetics can be tailored over 4 orders of magnitude by adjusting the selenourea structure. The wide range of conversion reactivity allows the extent of nucleation ([nanocrystal] = 4.6-56.7 μM) and the size following complete precursor conversion (d = 1.7-6.6 nm) to be controlled. Narrow size distributions (σ = 0.5-2%) are obtained whose spectral line widths are dominated (73-83%) by the intrinsic single particle spectral broadening, as observed using spectral hole burning measurements. The intrinsic broadening decreases with increasing size (fwhm = 320-65 meV, d = 1.6-4.4 nm) that derives from exciton fine structure and exciton-phonon coupling rather than broadening caused by the size distribution.
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Affiliation(s)
- Michael P Campos
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Mark P Hendricks
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Alexander N Beecher
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Willem Walravens
- Department of Chemistry, Columbia University , New York, New York 10027, United States.,Physics and Chemistry of Nanostructures Group (PCN), Ghent University , B-9000 Ghent, Belgium
| | - Robert A Swain
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Gregory T Cleveland
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Zeger Hens
- Physics and Chemistry of Nanostructures Group (PCN), Ghent University , B-9000 Ghent, Belgium.,Center of Nano and Biophotonics, Ghent University , B-9000 Ghent, Belgium
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Jonathan S Owen
- Department of Chemistry, Columbia University , New York, New York 10027, United States
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8
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Anderson NC, Hendricks MP, Choi JJ, Owen JS. Ligand exchange and the stoichiometry of metal chalcogenide nanocrystals: spectroscopic observation of facile metal-carboxylate displacement and binding. J Am Chem Soc 2013; 135:18536-48. [PMID: 24199846 PMCID: PMC4102385 DOI: 10.1021/ja4086758] [Citation(s) in RCA: 418] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We demonstrate that metal carboxylate complexes (L-M(O2CR)2, R = oleyl, tetradecyl, M = Cd, Pb) are readily displaced from carboxylate-terminated ME nanocrystals (ME = CdSe, CdS, PbSe, PbS) by various Lewis bases (L = tri-n-butylamine, tetrahydrofuran, tetradecanol, N,N-dimethyl-n-butylamine, tri-n-butylphosphine, N,N,N',N'-tetramethylbutylene-1,4-diamine, pyridine, N,N,N',N'-tetramethylethylene-1,2-diamine, n-octylamine). The relative displacement potency is measured by (1)H NMR spectroscopy and depends most strongly on geometric factors such as sterics and chelation, although also on the hard/soft match with the cadmium ion. The results suggest that ligands displace L-M(O2CR)2 by cooperatively complexing the displaced metal ion as well as the nanocrystal. Removal of up to 90% of surface-bound Cd(O2CR)2 from CdSe and CdS nanocrystals decreases the Cd/Se ratio from 1.1 ± 0.06 to 1.0 ± 0.05, broadens the 1S(e)-2S(3/2h) absorption, and decreases the photoluminescence quantum yield (PLQY) from 10% to <1% (CdSe) and from 20% to <1% (CdS). These changes are partially reversed upon rebinding of M(O2CR)2 at room temperature (∼60%) and fully reversed at elevated temperature. A model is proposed in which electron-accepting M(O2CR)2 complexes (Z-type ligands) reversibly bind to nanocrystals, leading to a range of stoichiometries for a given core size. The results demonstrate that nanocrystals lack a single chemical formula, but are instead dynamic structures with concentration-dependent compositions. The importance of these findings to the synthesis and purification of nanocrystals as well as ligand exchange reactions is discussed.
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Affiliation(s)
- Nicholas C. Anderson
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Mark P. Hendricks
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Joshua J. Choi
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Jonathan S. Owen
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
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9
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Hendricks MP, Cossairt BM, Owen JS. The importance of nanocrystal precursor conversion kinetics: mechanism of the reaction between cadmium carboxylate and cadmium bis(diphenyldithiophosphinate). ACS Nano 2012; 6:10054-10062. [PMID: 23043371 DOI: 10.1021/nn303769h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We describe the synthesis of cadmium bis(diphenyldithiophosphinate) (Cd(S(2)PPh(2))(2)) from secondary phosphine sulfides and its conversion to cadmium sulfide nanocrystals. Heating Cd(S(2)PPh(2))(2) and cadmium tetradecanoate (≥4 equiv) to 240 °C results in complete conversion of Cd(S(2)PPh(2))(2) to cadmium sulfide nanocrystals with tetradecanoate surface termination. The nanocrystals have a narrow size distribution (d = 3.8-4.1 nm, σ < 10%) that is evident from the line width of the lowest energy absorption feature (λ = 412-422 nm, fwhm = 0.17 eV) and display bright photoluminescence (PLQY(band edge+trap) = 36%). Interestingly, the final diameter is insensitive to the reaction conditions, including the total concentration of precursors and initial cadmium to sulfur ratio. Monitoring the reaction with (31)P NMR, UV-visible, and infrared absorption spectroscopies shows that the production of cadmium diphenylphosphinate (Cd(O(2)PPh(2))(2)) and tetradecanoic anhydride co-products is coupled with the formation of cadmium sulfide. From these measurements we propose a balanced chemical equation for the conversion reaction and use it to optimize a synthesis that affords CdS nanocrystals in quantitative yield. In light of these results we discuss the importance of well-defined precursor reactivity to reproducible conversion kinetics and the synthesis of nanocrystals with unambiguous chemical composition.
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Affiliation(s)
- Mark P Hendricks
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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