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He C, Weinberg DJ, Nepomnyashchii AB, Lian S, Weiss EA. Control of the Redox Activity of PbS Quantum Dots by Tuning Electrostatic Interactions at the Quantum Dot/Solvent Interface. J Am Chem Soc 2016; 138:8847-54. [PMID: 27341608 DOI: 10.1021/jacs.6b03970] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This paper describes the control of electron exchange between a colloidal PbS quantum dot (QD) and a negatively charged small molecule (9,10-anthraquinone-2-sulfonic acid sodium salt, AQ), through tuning of the charge density in the ligand shell of the QD, within an aqueous dispersion. The probability of electron exchange, measured through steady-state and time-resolved optical spectroscopy, is directly related to the permeability of the protective ligand shell, which is a mixed monolayer of negatively charged 6-mercaptohexanoate (MHA) and neutral 6-mercaptohexanol (MHO), to AQ. The composition of the ligand shell is quantitatively characterized by (1)H NMR. The dependence of the change in Gibbs free energy, ΔGobs, for the diffusion of AQ through the charged ligand shell and its subsequent adsorption to the QD surface is well-described with an electrostatic double-layer model for the QD/solvent interface. Fits of the optical data to this model yield an increase in the free energy for transfer of AQ from bulk solution to the surface of the QD (where it exchanges electrons with the QD) of 154 J/mol upon introduction of each additional charged MHA ligand to the ligand shell. This work expands the set of chemical parameters useful for controlling the redox activity of QDs via surface modification and suggests strategies for the use of nanoparticles for molecular and biomolecular recognition within chemically complex environments and for design of chemically stable nanoparticles for aqueous photocatalytic systems.
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Affiliation(s)
- Chen He
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - David J Weinberg
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Alexander B Nepomnyashchii
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Shichen Lian
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University , 2145 Sheridan Rd., Evanston, Illinois 60208-3113, United States
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102
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Young RM, Jensen SC, Edme K, Wu Y, Krzyaniak MD, Vermeulen NA, Dale EJ, Stoddart JF, Weiss EA, Wasielewski MR, Co DT. Ultrafast Two-Electron Transfer in a CdS Quantum Dot-Extended-Viologen Cyclophane Complex. J Am Chem Soc 2016; 138:6163-70. [PMID: 27111529 DOI: 10.1021/jacs.5b13386] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Time-resolved optical spectroscopies reveal multielectron transfer from the biexcitonic state of a CdS quantum dot to an adsorbed tetracationic compound cyclobis(4,4'-(1,4-phenylene) bipyridin-1-ium-1,4-phenylene-bis(methylene)) (ExBox(4+)) to form both the ExBox(3+•) and the doubly reduced ExBox(2(+•)) states from a single laser pulse. Electron transfer in the single-exciton regime occurs in 1 ps. At higher excitation powers the second electron transfer takes ∼5 ps, which leads to a mixture of redox states of the acceptor ligand. The doubly reduced ExBox(2(+•)) state has a lifetime of ∼10 ns, while CdS(+•):ExBox(3+•) recombines with multiple time constants, the longest of which is ∼300 μs. The long-lived charge separation and ability to accumulate multiple charges on ExBox(4+) demonstrate the potential of the CdS:ExBox(4+) complex to serve as a platform for two-electron photocatalysis.
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Affiliation(s)
- Ryan M Young
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Stephen C Jensen
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Kedy Edme
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Yilei Wu
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Matthew D Krzyaniak
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Nicolaas A Vermeulen
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Edward J Dale
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - J Fraser Stoddart
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Dick T Co
- Department of Chemistry and ‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States
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103
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Carroll GM, Brozek CK, Hartstein KH, Tsui EY, Gamelin DR. Potentiometric Measurements of Semiconductor Nanocrystal Redox Potentials. J Am Chem Soc 2016; 138:4310-3. [PMID: 26978480 DOI: 10.1021/jacs.6b00936] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A potentiometric method for measuring redox potentials of colloidal semiconductor nanocrystals (NCs) is described. Fermi levels of colloidal ZnO NCs are measured in situ during photodoping, allowing correlation of NC redox potentials and reduction levels. Excellent agreement is found between electrochemical and optical redox-indicator methods. Potentiometry is also reported for colloidal CdSe NCs, which show more negative conduction-band-edge potentials than in ZnO. This difference is highlighted by spontaneous electron transfer from reduced CdSe NCs to ZnO NCs in solution, with potentiometry providing a measure of the inter-NC electron-transfer driving force. Future applications of NC potentiometry are briefly discussed.
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Affiliation(s)
- Gerard M Carroll
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Carl K Brozek
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Kimberly H Hartstein
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Emily Y Tsui
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
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104
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Harrington JA, Harms ZD, Zaleski JM. Electrostatic assembly of gold nanorods on a glass substrate for sustainable photocatalytic reduction via sodium borohydride. RSC Adv 2016. [DOI: 10.1039/c6ra09613a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Gold nanorods were adhered onto a glass substrate for use as a sustainable, reusable photocatalyst to reduce 4-nitroaniline with sodium borohydride.
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105
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Beltrán A, Burguete MI, Luis SV, Galindo F. Characterization of amine stabilized CdSe/ZnS core–shell quantum dots by using triarylpyrylium dyes. RSC Adv 2016. [DOI: 10.1039/c6ra09614j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A new method to study the stabilizing primary amine ligands coordinated to the surface of CdSe/ZnS core–shell quantum dots has been developed.
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Affiliation(s)
- Alicia Beltrán
- Universitat Jaume I
- Departamento de Química Inorgánica y Orgánica
- Castellón
- Spain
| | - M. Isabel Burguete
- Universitat Jaume I
- Departamento de Química Inorgánica y Orgánica
- Castellón
- Spain
| | - Santiago V. Luis
- Universitat Jaume I
- Departamento de Química Inorgánica y Orgánica
- Castellón
- Spain
| | - Francisco Galindo
- Universitat Jaume I
- Departamento de Química Inorgánica y Orgánica
- Castellón
- Spain
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