1
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Samuthirapandi K, Durairaj P, Sarkar S. Interfacial Charge Transfer in Photoexcited QD-Molecule Composite of Tetrahedral CdSe Quantum Dot Coupled with Carbazole. ACS APPLIED MATERIALS & INTERFACES 2024; 16:31045-31055. [PMID: 38857441 DOI: 10.1021/acsami.4c02443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Photoexcited charge transfer dynamics in CdSe quantum dots (QDs) coupled with carbazole were explored to model QD-molecule systems for light-harvesting applications. The absorption spectra of QDs with different sizes, i.e., Cd35Se20X30L30 (T1), Cd56Se35X42L42 (T2), and Cd84Se56X56L56 (T3) were simulated with quantum dynamical methods, which qualitatively match the reported experimental spectra. The carbazole is attached with a 3-amino group at the apex position of T1 (namely T1-3A-Cz), establishing proper electronic communication between T1 and carbazole. The spectra of T1-3A-Cz is 0.22 eV red-shifted compared to T1. A time-dependent perturbation was applied in tune with the lowest energy peak (3.63 eV) of T1-3A-Cz to investigate the charge transfer dynamics, which revealed an ultrafast charge separation within the femtosecond time scale. The electronic structure showed a favorable energy alignment between T1 and carbazole in T1-3A-Cz. The LUMO of carbazole was situated below the conduction band of the QD, while the HOMO of carbazole mixed perfectly with the top of the valence band of the QD, developing the interfacial charge transfer states. These states promoted the photoexcited electron transfer directly from the CdSe core to carbazole. A rapid and enhanced charge separation occurred with the laser field strength increasing from 0.001 to 0.005 V/Å. However, T1 connected to the other positions of carbazole did not show charge separation effectively. The photoinduced charge transfer is negligible in the case of T2-carbazole systems due to poor electronic coupling, and it is not observed in T3-carbazole systems. So, the T1-3A-Cz model acts as a perfect donor-acceptor QD-molecule nanocomposite that can harvest photon energy efficiently. Further enhancement of charge transfer can be achieved by coupling more carbazoles to the T1 QD (e.g., T1-3A-Cz2) due to the extension of hole delocalization between T1 and the carbazoles.
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Affiliation(s)
| | - Pandiselvi Durairaj
- Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015, India
| | - Sunandan Sarkar
- Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015, India
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2
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Bhati M, Ivanov SA, Senftle TP, Tretiak S, Ghosh D. How structural and vibrational features affect optoelectronic properties of non-stoichiometric quantum dots: computational insights. NANOSCALE 2023; 15:7176-7185. [PMID: 37013402 DOI: 10.1039/d2nr06785d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
While stoichiometric quantum dots (QDs) have been well studied, a significant knowledge gap remains in the atomistic understanding of the non-stoichiometric ones, which are predominantly present during the experimental synthesis. Here, we investigate the effect of thermal fluctuations on structural and vibrational properties of non-stoichiometric cadmium selenide (CdSe) nanoclusters: anion-rich (Se-rich) and cation-rich (Cd-rich) using ab initio molecular dynamics (AIMD) simulations. While the excess atoms on the surface fluctuate more for a given QD type, the optical phonon modes are mostly composed of Se atoms dynamics, irrespective of the composition. Moreover, Se-rich QDs have higher bandgap fluctuations compared to Cd-rich QDs, suggesting poor optical properties of Se-rich QDs. Additionally, non-adiabatic molecular dynamics (NAMD) suggests faster non-radiative recombination for Cd-rich QDs. Altogether, this work provides insights into the dynamic electronic properties of non-stoichiometric QDs and proposes a rationale for the observed optical stability and superiority of cation-rich candidates for light emission applications.
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Affiliation(s)
- Manav Bhati
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei A Ivanov
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Thomas P Senftle
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Dibyajyoti Ghosh
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Materials Science and Engineering and Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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3
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Abstract
Anisotropic heterostructures of colloidal nanocrystals embed size-, shape-, and composition-dependent electronic structure within variable three-dimensional morphology, enabling intricate design of solution-processable materials with high performance and programmable functionality. The key to designing and synthesizing such complex materials lies in understanding the fundamental thermodynamic and kinetic factors that govern nanocrystal growth. In this review, nanorod heterostructures, the simplest of anisotropic nanocrystal heterostructures, are discussed with respect to their growth mechanisms. The effects of crystal structure, surface faceting/energies, lattice strain, ligand sterics, precursor reactivity, and reaction temperature on the growth of nanorod heterostructures through heteroepitaxy and cation exchange reactions are explored with currently known examples. Understanding the role of various thermodynamic and kinetic parameters enables the controlled synthesis of complex nanorod heterostructures that can exhibit unique tailored properties. Selected application prospects arising from such capabilities are then discussed.
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Affiliation(s)
- Gryphon A Drake
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
| | - Logan P Keating
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
| | - Moonsub Shim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 United States
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4
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Li W, Li K, Zhao X, Liu C, Coudert FX. Defective Nature of CdSe Quantum Dots Embedded in Inorganic Matrices. J Am Chem Soc 2022; 144:11296-11305. [PMID: 35713308 DOI: 10.1021/jacs.2c03039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum dots (QDs) embedded in inorganic matrices have been extensively studied for their potential applications in lighting, displays, and solar cells. While a significant amount of research studies focused on their experimental fabrication, the origin of their relatively low photoluminescence quantum yield has not been investigated yet, although it severely hinders practical applications. In this study, we use time-dependent density functional theory (TDDFT) to pinpoint the nature of excited states of CdSe QDs embedded in various inorganic matrices. The formation of undercoordinated Se atoms and nonbridging oxygen atoms at the QD/glass interface is responsible for the localization of a hole wave function, leading to the formation of low-energy excited states with weak oscillator strength. These states provide pathways for nonradiative processes and compete with radiative emission. The photoluminescence performance is predicted for CdSe QDs in different matrices and validated by experiments. The results of this study have significant implications for understanding the underlying photophysics of CdSe QDs embedded in inorganic matrices that would facilitate the fabrication of highly luminescent glasses.
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Affiliation(s)
- Wenke Li
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China.,Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, Paris 75005, France
| | - Kai Li
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - Xiujian Zhao
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - Chao Liu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - François-Xavier Coudert
- Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, Paris 75005, France
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5
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Foerster A, Besley NA. Quantum Chemical Characterization and Design of Quantum Dots for Sensing Applications. J Phys Chem A 2022; 126:2899-2908. [PMID: 35502789 PMCID: PMC9125561 DOI: 10.1021/acs.jpca.2c00947] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The ability to tune
the optoelectronic properties of quantum dots
(QDs) makes them ideally suited for the use as fluorescence sensing
probes. The vast structural diversity in terms of the composition
and size of QDs can make designing a QD for a specific sensing application
a challenging process. Quantum chemical calculations have the potential
to aid this process through the characterization of the properties
of QDs, leading to their in silico design. This is
explored in the context of QDs for the fluorescence sensing of dopamine
based upon density functional theory and time-dependent density functional
theory (TDDFT) calculations. The excited states of hydrogenated carbon,
silicon, and germanium QDs are characterized through TDDFT calculations.
Analysis of the molecular orbital diagrams for the isolated molecules
and calculations of the excited states of the dopamine-functionalized
quantum dots establish the possibility of a photoinduced electron-transfer
process by determining the relative energies of the electronic states
formed from a local excitation on the QD and the lowest QD →
dopamine electron-transfer state. The results suggest that the Si165H100 and Ge84H64 QDs have
the potential to act as fluorescent markers that could distinguish
between the oxidized and reduced forms of dopamine, where the fluorescence
would be quenched for the oxidized form. The work contributes to a
better understanding of the optical and electronic behavior of QD-based
sensors and illustrates how quantum chemical calculations can be used
to inform the design of QDs for specific fluorescent sensing applications.
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Affiliation(s)
- Aleksandra Foerster
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
| | - Nicholas A Besley
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
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6
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Ahn J, Jeon S, Woo HK, Bang J, Lee YM, Neuhaus SJ, Lee WS, Park T, Lee SY, Jung BK, Joh H, Seong M, Choi JH, Yoon HG, Kagan CR, Oh SJ. Ink-Lithography for Property Engineering and Patterning of Nanocrystal Thin Films. ACS NANO 2021; 15:15667-15675. [PMID: 34495639 DOI: 10.1021/acsnano.1c04772] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Next-generation devices and systems require the development and integration of advanced materials, the realization of which inevitably requires two separate processes: property engineering and patterning. Here, we report a one-step, ink-lithography technique to pattern and engineer the properties of thin films of colloidal nanocrystals that exploits their chemically addressable surface. Colloidal nanocrystals are deposited by solution-based methods to form thin films and a local chemical treatment is applied using an ink-printing technique to simultaneously modify (i) the chemical nature of the nanocrystal surface to allow thin-film patterning and (ii) the physical electronic, optical, thermal, and mechanical properties of the nanocrystal thin films. The ink-lithography technique is applied to the library of colloidal nanocrystals to engineer thin films of metals, semiconductors, and insulators on both rigid and flexible substrates and demonstrate their application in high-resolution image replications, anticounterfeit devices, multicolor filters, thin-film transistors and circuits, photoconductors, and wearable multisensors.
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Affiliation(s)
- Junhyuk Ahn
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Sanghyun Jeon
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Ho Kun Woo
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Junsung Bang
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Yong Min Lee
- Department of Semiconductor Systems Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Steven J Neuhaus
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Woo Seok Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Taesung Park
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Sang Yeop Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Byung Ku Jung
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Hyungmok Joh
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Mingi Seong
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Ji-Hyuk Choi
- Mineral Utilization Convergence Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea
| | - Ho Gyu Yoon
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Cherie R Kagan
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Soong Ju Oh
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
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7
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Phototriggered cytotoxic properties of tricarbonyl manganese(I) complexes bearing α-diimine ligands towards HepG2. J Biol Inorg Chem 2021; 26:135-147. [PMID: 33638701 DOI: 10.1007/s00775-020-01843-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 12/01/2020] [Indexed: 11/27/2022]
Abstract
Reaction between bromo tricarbonyl manganese(I) and N,N'-bis(phenyl)-1,4-diaza-1,3-butadiene ligands, bearing different electron-donating and electron-withdrawing groups R = OCH3, Cl, and NO2 in the ortho- and para-positions on the phenyl substituent, afforded [MnBr(CO)3(N-N)] complexes. The influence of the character and position of the substituent on the dark stability and carbon monoxide releasing kinetics was systematically investigated and correlated with the data of the time-dependent density functional theory calculations. The combined UV/Vis and IR data clearly revealed that the aerated solutions of [MnBr(CO)3(N-N)] in either coordinating or noncoordinating solvents are dark stable and the fluctuations observed during the incubation period especially in the case of the nitro derivatives may be attributed to the exchange of the axial bromo ligand with the coordinating solvent molecules. The free ligands and nitro complexes were non-cytotoxic to HepG2 cells under both the dark and illumination conditions. In the dark, Mn(I) compounds, incorporating o-OCH3 and o-Cl, exhibited excellent cytotoxicity with IC50 values of 18.1 and 11.8 μM, while their para-substituted analogues were inactive in the dark and active upon the irradiation at 365 nm with IC50 values of 5.7 and 6.7 μM, respectively.
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8
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Mansour AM, Radacki K. Terpyridine based ReX(CO)3 compounds (X = Br–, N3– and triazolate): Spectroscopic and DFT studies. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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9
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Coden M, De Checchi P, Fresch B. Spectral shift, electronic coupling and exciton delocalization in nanocrystal dimers: insights from all-atom electronic structure computations. NANOSCALE 2020; 12:18124-18136. [PMID: 32852028 DOI: 10.1039/d0nr05601d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Delocalization of excitons promoted by electronic coupling between clusters or quantum dots (QD) changes the dynamical processes in nanostructured aggregates enhancing energy transport. A spectroscopic shift of the absorption spectrum upon QD aggregation is commonly observed and ascribed to quantum mechanical coupling between neighbouring dots but also to exciton delocalization over the sulphur-based ligand shell or to other mechanisms as a change in the dielectric constant of the surrounding medium. We address the question of electronic coupling and exciton delocalization in nanocrystal aggregates by performing all-atom electronic structure calculations in models of colloidal QD dimers. The relation between spectral shift, interdot coupling and exciton delocalization is investigated in atomistic detail in models of dimers formed by CdSe clusters kept together by bridging organic ligands. Our results support the possibility of obtaining exciton delocalization over the dimer and point out the crucial role of the bridging ligand in enhancing interdot electronic coupling.
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Affiliation(s)
- Maurizio Coden
- Department of Chemical Sciences, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy.
| | - Pietro De Checchi
- Department of Chemical Sciences, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy.
| | - Barbara Fresch
- Department of Chemical Sciences, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy.
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10
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Jones LO, Mosquera MA, Jiang Y, Weiss EA, Schatz GC, Ratner MA. Thermodynamics and Mechanism of a Photocatalyzed Stereoselective [2 + 2] Cycloaddition on a CdSe Quantum Dot. J Am Chem Soc 2020; 142:15488-15495. [DOI: 10.1021/jacs.0c07130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Leighton O. Jones
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Martín A. Mosquera
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Yishu Jiang
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Emily A. Weiss
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Bio-Inspired Energy Science (CBES), Northwestern University, Evanston, Illinois 60208, United States
| | - George C. Schatz
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Bio-Inspired Energy Science (CBES), Northwestern University, Evanston, Illinois 60208, United States
- Institute for Catalysis in Energy Processes (ICEP), Northwestern University, Evanston, Illinois 60208, United States
| | - Mark A. Ratner
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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11
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Khaled RM, Friedrich A, Ragheb MA, Abdel-Ghani NT, Mansour AM. Cytotoxicity of photoactivatable bromo tricarbonyl manganese(i) compounds against human liver carcinoma cells. Dalton Trans 2020; 49:9294-9305. [PMID: 32578643 DOI: 10.1039/d0dt01539c] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Two series of photoinduced tricarbonyl manganese(i) compounds were prepared from the reaction of [MnBr(CO)3(2-C(H)[double bond, length as m-dash]O)] (2-C(H)[double bond, length as m-dash]O: quinoline-2-carboxaldehyde and pyridine-2-carboxaldehyde) and para-substituted aniline derivatives (X = OH, OCH3, Cl and NO2). Different electron-donating and electron-withdrawing substituents were introduced in the para-position of the phenyl ring to investigate their influence on the stability of the compounds in the dark and the photophysical properties upon illumination at 525 nm. When kept in the dark, the aerated solutions of the complexes in dimethyl sulfoxide (DMSO) and CH2Cl2 were stable. In the solution, the complexes bearing electron-withdrawing substituents, exchange their bromo ligands with DMSO solvent molecules, as evidenced from infrared and UV/Vis studies as well as time-dependent density functional theory (TDDFT) calculations. The complexes were assessed for their cytotoxicity, both in the dark and upon exposure to a 525 nm LED, against the human hepatocarcinoma cell line (HepG2). A marked reduction in the viability of HepG2 cells treated with the complex functionalized with quinoline and methoxy substituent was observed after illumination in a dose-dependent manner, with an IC50 value of 7.1 μM, making it the most phototoxic compound in our study.
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Affiliation(s)
- Rabaa M Khaled
- Department of Chemistry, Faculty of Science, Cairo University, Gamma Street, Giza, Cairo 12613, Egypt.
| | - Alexandra Friedrich
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Mohamed A Ragheb
- Department of Chemistry, Faculty of Science, Cairo University, Gamma Street, Giza, Cairo 12613, Egypt.
| | - Nour T Abdel-Ghani
- Department of Chemistry, Faculty of Science, Cairo University, Gamma Street, Giza, Cairo 12613, Egypt.
| | - Ahmed M Mansour
- Department of Chemistry, Faculty of Science, Cairo University, Gamma Street, Giza, Cairo 12613, Egypt.
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12
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Yu S, Huang D, Withanage K. Computational insights into structural and optical properties of P-containing and N-containing ligands capped CdSe clusters. MOLECULAR SIMULATION 2019. [DOI: 10.1080/08927022.2019.1642473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Shengping Yu
- College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu, People’s Republic of China
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, People’s Republic of China
| | - Delin Huang
- College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu, People’s Republic of China
| | - Kushantha Withanage
- Physics Department and Science of Advanced Materials Ph. D Program, Central Michigan University, Mount Pleasant, MI, USA
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13
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Zhang J, Zhang H, Cao W, Pang Z, Li J, Shu Y, Zhu C, Kong X, Wang L, Peng X. Identification of Facet-Dependent Coordination Structures of Carboxylate Ligands on CdSe Nanocrystals. J Am Chem Soc 2019; 141:15675-15683. [PMID: 31503473 DOI: 10.1021/jacs.9b07836] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Aliphatic carboxylates are the most common class of surface ligands to stabilize colloidal nanocrystals. The widely used approach to identify the coordination modes between surface cationic sites and carboxylate ligands is based on the empirical infrared (IR) spectroscopic assignment, which is often ambiguous and thus hampers the practical control of surface structures. In this report, multiple techniques based on nuclear magnetic resonance (NMR) and IR spectra are applied to distinguish the different coordination structures in a series of zinc-blende CdSe nanocrystals with unique facet structures, including nanoplatelets dominated with {100} basal planes, hexahedrons with only three types of low-index facets (i.e., {100}, {110}, and {111}), and spheroidal dots without well-defined facets. Interpretation and assignment of NMR and IR signals were assisted by density functional theory (DFT) calculations. In addition to the identification of facet-sensitive bonding modes, the present methods also allow a nondestructive quantification of mixed ligands.
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Affiliation(s)
- Jun Zhang
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Haibing Zhang
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Weicheng Cao
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Zhenfeng Pang
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Jiongzhao Li
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Yufei Shu
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Chenqi Zhu
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Xueqian Kong
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Linjun Wang
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
| | - Xiaogang Peng
- Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry , Zhejiang University , Hangzhou 310027 , P. R. China
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14
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Chen Q, Zheng J, Yang Q, Dang Z, Zhang L. Insights into the Glyphosate Adsorption Behavior and Mechanism by a MnFe 2O 4@Cellulose-Activated Carbon Magnetic Hybrid. ACS APPLIED MATERIALS & INTERFACES 2019; 11:15478-15488. [PMID: 30950258 DOI: 10.1021/acsami.8b22386] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To enhance the removal of the negatively charged organophosphorus pesticide (OPP) glyphosate (GLY), we prepared a positively charged MnFe2O4@cellulose activated carbon (CAC) hybrid by immobilizing MnFe2O4 nanoparticles on the CAC surface via a simple one-pot solvothermal method, scanning electron microscopy, BET, transmission electron microscopy, IR, Raman, X-ray diffraction, and X-ray photoelectron spectroscopy analysis which proved the successful synthesis of MnFe2O4 with a particle size of 100-300 nm. The particles were distributed on the surface of CAC to form the MnFe2O4@CAC hybrid. MnFe2O4@CAC exhibited a positive charge at pH below 6 and had good magnetic properties and dispersion stability. The maximum GLY adsorption capacity of MnFe2O4@CAC (167.2 mg/g) was much higher than that of CAC (61.44 mg/g) and MnFe2O4 nanoparticles (93.48 mg/g). The adsorption process was dominated by chemisorption, and the formation of new chemical bonds between GLY and MnFe2O4 was confirmed by simulations. The newly formed chemical bonds were attributed to the conjugation between p electrons of the adsorbent and the d electrons of the adsorbate. Collectively, the results indicate that the as-prepared MnFe2O4@CAC is promising for anionic pollutant adsorption and the removal of OPPs, and our mechanistic results are of guiding significance in environmental cleanup.
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Affiliation(s)
- Quan Chen
- Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Jiewei Zheng
- Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Qian Yang
- Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Zhi Dang
- School of Environment and Energy , South China University of Technology , Guangzhou 510006 , P. R. China
| | - Lijuan Zhang
- Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
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15
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Hartley CL, Dempsey JL. Electron-Promoted X-Type Ligand Displacement at CdSe Quantum Dot Surfaces. NANO LETTERS 2019; 19:1151-1157. [PMID: 30640472 DOI: 10.1021/acs.nanolett.8b04544] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Quantum dot surfaces are redox active and are known to influence the electronic properties of nanocrystals, yet the molecular-level changes in surface chemistry that occur upon addition of charge are not well understood. In this paper, we report a systematic study monitoring changes in surface coordination chemistry in 3.4 nm CdSe quantum dots upon remote chemical doping by the radical anion reductant sodium naphthalenide (Na[C10H8]). These studies reveal a new mechanism for charge-balancing the added electrons that localize on surface states through loss of up to ca. 5% of the native anionic carboxylate ligands, as quantified through a combination of UV-vis absorption, 1H NMR, and FTIR spectroscopies. A new method for distinguishing between reduction of surface metal and chalcogenide ions by monitoring ligand loss and optical changes upon doping is introduced. This work emphasizes the importance of studying changes in surface chemistry with remote chemical doping and is more broadly contextualized within the redox reactivity of the QD surface.
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Affiliation(s)
- Carolyn L Hartley
- Department of Chemistry , University of North Carolina , Chapel Hill , North Carolina 27599-3290 , United States
| | - Jillian L Dempsey
- Department of Chemistry , University of North Carolina , Chapel Hill , North Carolina 27599-3290 , United States
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Qi T, Lyu YJ, Wang ZM, Yang HQ, Hu CW. Regular patterns of the effects of hydrogen-containing additives on the formation of CdSe monomer. Phys Chem Chem Phys 2018; 20:20863-20873. [PMID: 30066703 DOI: 10.1039/c8cp02980f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It is unclear at the molecular level why HY (HY = RSH, or ROH, or RNH2) with HPPh2 additives kinetically affects the reaction pathway to the formation of different monomers (Ph2P-SeCd-Y or Ph2P-SeCdSe-Y) in the systhesis of semiconductor nanocrystals. In the present work, it was found that in a [Cd(OA)2 + Se[double bond, length as m-dash]P(C8H17)3 + HPPh2 + HY] mixture, HY behaves as a mediator for the formation of the initial kind of monomer, besides as a hydrogen/proton donor in the release of oleic acid and as an accelerant in the Se-P bond cleavage, which follows the mechanism of hydrogen-shift/nucleophilic-attack. The capability of the HY additive to provide a H-source decreases in the order SePPh2H > RSH > HPPh2 > ROH > RNH2, while the performance of HY to accelerate Se-P bond cleavage decreases in the order HPPh2 > RSH > RNH2 > ROH. The capacity of HY to promote the formation of the Ph2P-SeCd-Y monomer decreases in the order RSH > HPPh2 > ROH > RNH2, while the effect of HY to drive the formation of the Ph2P-SeCdSe-Y monomer decreases in the order HPPh2 > RSH > RNH2 > ROH. The activation strain energy plays a key role in both the Se-P and H-Y bond cleavage, which correlates negatively to the size of the coordinated atom radius. When only HPPh2 is present without other HY species (HY = RNH2, or RSH, or ROH), Ph2P-SeCdSe-PPh2 is preferentially formed. Alternatively, when both HY (HY = RNH2, or RSH, or ROH) and HPPh2 are present, Ph2P-SeCd-Y is favorably formed. For the formation of Ph2P-SeCd-Y (Y = -PPh2, -SR, -OR, and -NHR), SePPh2H embodies the catalytic performance, while HPPh2 serves as the catalyst for the formation of Ph2P-SeCdSe-Y (Y = -NHR or -OR). Our study brings a molecular-level insight into the relationship between the CdSe monomer and the phosphorous-containing side-product, which may advance the rational design and synthesis of quantum dots.
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Affiliation(s)
- Ting Qi
- College of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China.
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