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Brodie CN, Owen AE, Kolb JS, Bühl M, Kumar A. Synthesis of Polyethyleneimines from the Manganese Catalyzed Coupling of Ethylene Glycol and Ethylenediamine. Angew Chem Int Ed Engl 2023:e202306655. [PMID: 37195140 DOI: 10.1002/anie.202306655] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 05/18/2023]
Abstract
Polyethyleneimines find many applications in products such as detergents, adhesives, cosmetics, and for processes such as tissue culture, gene therapy, and CO2 capture. The current state-of-the-art technology for the production of the branched polyethyleneimines involves aziridine feedstock which is a highly toxic, volatile and mutagenic chemical and raises significant concern to human health and environment. We report here a novel method for the synthesis of branched polyethyleneimines from ethylene glycol and ethylenediamine feedstock which are much safer, environmentally benign, commercially available and potentially renewable feedstock. The polymerisation reaction is catalysed by a complex of an earth-abundant metal, manganese and liberates H2O as the only by-product. Our mechanistic studies using a combination of DFT computation and experiment suggest that the reaction proceeds by the formation and subsequent hydrogenation of imine intermediates.
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Affiliation(s)
| | | | | | - Michael Bühl
- University of St Andrews, Chemistry, UNITED KINGDOM
| | - Amit Kumar
- Saint Andrews University, Chemistry, North Haugh, KY169ST, St. Andrews, UNITED KINGDOM
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2
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Ogunwale G, Louis H, Unimuke TO, Mathias GE, Owen AE, Edet HO, Enudi OC, Oluwasanmi EO, Adeyinka AS, Doust Mohammadi M. Interaction of 5-Fluorouracil on the Surfaces of Pristine and Functionalized Ca 12O 12 Nanocages: An Intuition from DFT. ACS Omega 2023; 8:13551-13568. [PMID: 37091381 PMCID: PMC10116506 DOI: 10.1021/acsomega.2c03635] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 01/11/2023] [Indexed: 05/03/2023]
Abstract
The utilization of nanostructured materials for several biomedical applications has tremendously increased over the last few decades owing to their nanosizes, porosity, large surface area, sensitivity, and efficiency as drug delivery systems. Thus, the incorporation of functionalized and pristine nanostructures for cancer therapy offers substantial prospects to curb the persistent problems of ineffective drug administration and delivery to target sites. The potential of pristine (Ca12O12) and formyl (-CHO)- and amino (-NH2)-functionalized (Ca12O12-CHO and Ca12O12-NH2) derivatives as efficient nanocarriers for 5-fluorouracil (5FU) was studied at the B3LYP-GD3(BJ)/6-311++G(d,p) theoretical level in two electronic media (gas and solvent). To effectively account for all adsorption interactions of the drug on the investigated surfaces, electronic studies as well as topological analysis based on the quantum theory of atoms in molecules (QTAIM) and noncovalent interactions were exhaustively utilized. Interestingly, the obtained results divulged that the 5FU drug interacted favorably with both Ca12O12 and its functionalized derivatives. The adsorption energies of pristine and functionalized nanostructures were calculated to be -133.4, -96.9, and -175.6 kcal/mol, respectively, for Ca12O12, Ca12O12-CHO, and Ca12O12-NH2. Also, both topological analysis and NBO stabilization analysis revealed the presence of interactions among O3-H32, O27-C24, O10-C27, and N24-H32 atoms of the drug and the surface. However, 5FU@Ca12O12-CHO molecules portrayed the least adsorption energy due to considerable destabilization of the molecular complex as revealed by the computed deformation energy. Therefore, 5FU@Ca12O12 and 5FU@Ca12O12-NH2 acted as better nanovehicles for 5FU.
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Affiliation(s)
- Goodness
J. Ogunwale
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Chemistry, Faculty of Science, University
of Ibadan, Ibadan200005, Nigeria
| | - Hitler Louis
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Tomsmith O. Unimuke
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Gideon E. Mathias
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Aniekan E. Owen
- School
of Chemistry, University of St Andrews, St AndrewsKY16 9ST, Scotland
| | - Henry O. Edet
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Obieze C. Enudi
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Chemistry, Faculty of Science, University
of Ibadan, Ibadan200005, Nigeria
| | - Esther O. Oluwasanmi
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Chemistry, Faculty of Science, University
of Ibadan, Ibadan200005, Nigeria
| | - Adedapo S. Adeyinka
- Department
of Chemical Sciences, University of Johannesburg, Johannesburg2006, South-Africa
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Owen AE, Louis H, Agwamba EC, Udoikono AD, Manicum ALE. Antihypotensive potency of p-synephrine: Spectral analysis, molecular properties and molecular docking investigation. J Mol Struct 2023. [DOI: 10.1016/j.molstruc.2022.134233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Asogwa FC, Apebende CG, Ugodi GW, Ebo P, Louis H, Ikeuba AI, Asogwa CJ, Gber TE, Ikot IJ, Owen AE. Anti-inflammatory, Immunomodulatory and DFT Evaluation of the Reactivity Indexes of Phytochemicals Isolated from Harungana madagascariensis. Chemistry Africa 2022. [DOI: 10.1007/s42250-022-00569-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Louis H, Ekereke EE, Isang BB, Ikeuba AI, Amodu IO, Gber TE, Owen AE, Adeyinka AS, Agwamba EC. Assessing the Performance of Al 12N 12 and Al 12P 12 Nanostructured Materials for Alkali Metal Ion (Li, Na, K) Batteries. ACS Omega 2022; 7:46183-46202. [PMID: 36570229 PMCID: PMC9773795 DOI: 10.1021/acsomega.2c04319] [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] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/26/2022] [Indexed: 06/17/2023]
Abstract
This study focused on the potential of aluminum nitride (Al12N12) and aluminum phosphide (Al12P12) nanomaterials as anode electrodes of lithium-ion (Li-ion), sodium-ion (Na-ion), and potassium-ion (K-ion) batteries as investigated via density functional theory (DFT) calculations at PBE0-D3, M062X-D3, and DSDPBEP86 as the reference method. The results show that the Li-ion battery has a higher cell voltage with a binding energy of -1.210 eV and higher reduction potential of -6.791 kcal/mol compared to the sodium and potassium ion batteries with binding energies of -0.749 and -0.935 eV and reduction potentials of -6.414 and -6.513 kcal/mol, respectively, using Al12N12 material. However, in Al12P12, increases in the binding energy and reduction potential were observed in the K-ion battery with values -1.485 eV and -7.535 kcal/mol higher than the Li and Na ion batteries with binding energy and reduction potential -1.483, -1.311 eV and -7.071, -7.184 eV, respectively. Finally, Al12N12 and Al12P12 were both proposed as novel anode electrodes in Li-ion and K-ion batteries with the highest performances.
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Affiliation(s)
- Hitler Louis
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Ernest E. Ekereke
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Mathematics, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Bartholomew B. Isang
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Mathematics, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Alexander I. Ikeuba
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Ismail O. Amodu
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Mathematics, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Terkumbur E. Gber
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar540221, Nigeria
| | - Aniekan E. Owen
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- School
of Chemistry, University of St Andrews, St AndrewsKY16 9ST, United Kingdom
| | - Adedapo S. Adeyinka
- Department
of Chemical Sciences, University of Johannesburg, Auckland Park2006South Africa
| | - Ernest C. Agwamba
- Computational
and Bio-Simulation Research Group, University
of Calabar, Calabar540221, Nigeria
- Department
of Chemistry, Covenant University, Ota50001, Nigeria
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Apebende CG, Louis H, Owen AE, Benjamin I, Amodu IO, Gber TE, Asogwa FC. Adsorption properties of metal functionalized fullerene (C 59Au, C 59Hf, C 59Ag, and C 59Ir) nanoclusters for application as a biosensor for hydroxyurea (HXU): insight from theoretical computation. Z PHYS CHEM 2022. [DOI: 10.1515/zpch-2022-0126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
This theoretical study was conducted to evaluate the efficiency of fullerene C60 and its metal functionalized nano clusters (C59Au, C59Hf, C59Ag and C59Ir) as a sensor for hydroxyurea (HXU). The various conclusions concerning the adsorption and sensing properties of the studied nano surfaces were achieved using density functional theory (DFT) at the M062X-D3/gen/LanL2DZ/def2svp level of theory. Among the nano clusters studied for this interaction, analysis of the HOMO–LUMO energy differences (E
g) showed that HXU@C59Hg (H2) reflects the least energy gap of 3.042 eV, indicating its greater reactivity, sensitivity and conductivity. Also, the adsorption phenomenon in this current study is best described as chemisorptions owing to the negative adsorption enthalpies observed. Thus, the adsorption energy (E
Ad) follows an increasing pattern of: HXU@C60 (C1) (−0.218 eV) < HXU@C59Ir (I1) (−1.361 eV) < HXU@C59Au (A1) (−1.986 eV) < HXU@C59Hf (H1) (−2.640 eV) < HXU@C59Hg (H2) (−3.347 eV). Least E
g, highest E
Ad and non-covalent nature of interaction attributed to C59Hg surface are sufficient to show that, among all studied surfaces, C59Hg surface emerged as the most suitable adsorbent for the adsorption of HXU. Hence, it can be used in modeling future adsorbent material for hydroxyurea.
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Affiliation(s)
- Chioma G. Apebende
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences , University of Calabar , Calabar , Nigeria
| | - Hitler Louis
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences , University of Calabar , Calabar , Nigeria
| | - Aniekan E. Owen
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
| | - Innocent Benjamin
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Microbiology, Faculty of Biological Sciences , University of Calabar , Calabar , Nigeria
| | - Ismail O. Amodu
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Mathematics, Faculty of Physical Sciences , University of Calabar , Calabar , Nigeria
| | - Terkumbur E. Gber
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences , University of Calabar , Calabar , Nigeria
| | - Fredrick C. Asogwa
- Computational and Bio-Simulation Research Group , University of Calabar , Calabar , Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences , University of Calabar , Calabar , Nigeria
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Louis H, Etiese D, Unimuke TO, Owen AE, Rajee AO, Gber TE, Chima CM, Eno EA, Nfor EN. Computational design and molecular modeling of the interaction of nicotinic acid hydrazide nickel-based complexes with H 2S gas. RSC Adv 2022; 12:30365-30380. [PMID: 36337983 PMCID: PMC9590404 DOI: 10.1039/d2ra05456f] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/10/2022] [Indexed: 01/14/2023] Open
Abstract
The application of nickel complexes of nicotinic acid hydrazide ligand as a potential gas-sensor and adsorbent material for H2S gas was examined using appropriate density functional theory (DFT) calculations with the ωB97XD/Gen/6-311++G(d,p)/LanL2DZ method. The FT-IR spectrum of the synthesized ligand exhibited a medium band at 3178 cm-1 attributed to ν(NH) stretching vibrations and strong bands at 1657 and 1600 cm-1 corresponding to the presence of ν(C[double bond, length as m-dash]O) and ν(C[double bond, length as m-dash]N) vibration modes. In the spectrum of the nickel(ii) complex, the ν(C[double bond, length as m-dash]O) and ν(C[double bond, length as m-dash]N) vibration bands experience negative shifts to 1605 cm-1 and 1580 cm-1, respectively, compared to the ligand. This indicates the coordination of the carbonyl oxygen and the azomethine nitrogen atoms to the Ni2+ ion. Thus, the sensing mechanism of the complexes indicated a short recovery time and that the work function value increases for all complexes, necessitating an excellent H2S gas sensor material. Thus, a profound assertion was given that the complex sensor surfaces exhibited very dense stability with regards to their relevant binding energies corresponding to various existing studies.
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Affiliation(s)
- Hitler Louis
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
| | - Daniel Etiese
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
| | - Tomsmith O. Unimuke
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
| | - Aniekan E. Owen
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Chemistry, Akwa-Ibom State UniversityUyoNigeria
| | | | - Terkumbur E. Gber
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
| | - Chioma M. Chima
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
| | - Ededet A. Eno
- Computational and Bio-Simulation Research Group, University of CalabarCalabarNigeria,Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of CalabarCalabarNigeria
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Louis H, Mathias GE, Unimuke TO, Emori W, Ling L, Owen AE, Adeyinka AS, Ntui TN, Cheng CR. Isolation, characterization, molecular electronic structure investigation, and in-silico modeling of the anti-inflammatory potency of trihydroxystilbene. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133418] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Benjamin I, Udoikono AD, Louis H, Agwamba EC, Unimuke TO, Owen AE, Adeyinka AS. Antimalarial potential of naphthalene-sulfonic acid derivatives: Molecular electronic properties, vibrational assignments, and in-silico molecular docking studies. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133298] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Emori W, Louis H, Adalikwu SA, Timothy RA, Cheng CR, Gber TE, Agwamba EC, Owen AE, Ling L, Offiong OE, Adeyinka AS. Molecular Modeling of the Spectroscopic, Structural, and Bioactive Potential of Tetrahydropalmatine: Insight from Experimental and Theoretical Approach. Polycycl Aromat Compd 2022. [DOI: 10.1080/10406638.2022.2110908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Wilfred Emori
- Key Laboratory of Material Corrosion and Protection of Sichuan Province, Zigong, Sichuan, P. R. China
- Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education, School of Materials Science and Engineering, Sichuan University of Science and Engineering, Zigong, Sichuan, P. R. China
| | - Hitler Louis
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Stephen A. Adalikwu
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
| | - Rawlings A. Timothy
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Chun-Ru Cheng
- Key Laboratory of Material Corrosion and Protection of Sichuan Province, Zigong, Sichuan, P. R. China
- Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education, College of Chemical Engineering, Institute of Pharmaceutical Engineering Technology and Application, Sichuan University of Science & Engineering, Zigong, Sichuan, P. R. China
| | - Terkumbur E. Gber
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Ernest C. Agwamba
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Chemical Sciences, Clifford University Owerrinta, Ihie, Nigeria
| | - Aniekan E. Owen
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
| | - Liu Ling
- Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education, College of Chemical Engineering, Institute of Pharmaceutical Engineering Technology and Application, Sichuan University of Science & Engineering, Zigong, Sichuan, P. R. China
| | - Offiong E. Offiong
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Adedapo S. Adeyinka
- Department of Chemical Sciences, Research Centre for Synthesis and Catalysis, University of Johannesburg, Johannesburg, South Africa
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Gber TE, Louis H, Owen AE, Etinwa BE, Benjamin I, Asogwa FC, Orosun MM, Eno EA. Heteroatoms (Si, B, N, and P) doped 2D monolayer MoS 2 for NH 3 gas detection. RSC Adv 2022; 12:25992-26010. [PMID: 36199611 PMCID: PMC9468912 DOI: 10.1039/d2ra04028j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 06/30/2022] [Accepted: 08/29/2022] [Indexed: 11/21/2022] Open
Abstract
2D transition metal dichalcogenide MoS2 monolayer quantum dots (MoS2-QD) and their doped boron (B@MoS2-QD), nitrogen (N@MoS2-QD), phosphorus (P@MoS2-QD), and silicon (Si@MoS2-QD) surfaces have been theoretically investigated using density functional theory (DFT) computation to understand their mechanistic sensing ability, such as conductivity, selectivity, and sensitivity toward NH3 gas. The results from electronic properties showed that P@MoS2-QD had the lowest energy gap, which indicated an increase in electrical conductivity and better adsorption behavior. By carrying out comparative adsorption studies using m062-X, ωB97XD, B3LYP, and PBE0 methods at the 6-311G++(d,p) level of theory, the most negative values were observed from ωB97XD for the P@MoS2-QD surface, signifying the preferred chemisorption surface for NH3 detection. The mechanistic studies provided in this study also indicate that the P@MoS2-QD dopant is a promising sensing material for monitoring ammonia gas in the real world. We hope this research work will provide informative knowledge for experimental researchers to realize the potential of MoS2 dopants, specifically the P@MoS2-QD surface, as a promising candidate for sensors to detect gas. 2D transition metal dichalcogenide MoS2 monolayer quantum dots (MoS2-QD) and their doped boron (B@MoS2-QD), nitrogen (N@MoS2-QD), phosphorus (P@MoS2-QD), and silicon (Si@MoS2-QD) counterparts are proposed as selective sensors for NH3 gas.![]()
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Affiliation(s)
- Terkumbur E. Gber
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Hitler Louis
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Chemistry, Akwa-Ibom State University, Uyo, Nigeria
| | - Aniekan E. Owen
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Chemistry, Akwa-Ibom State University, Uyo, Nigeria
| | - Benjamin E. Etinwa
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Innocent Benjamin
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | - Fredrick C. Asogwa
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
| | | | - Ededet A. Eno
- Computational and Bio-Simulation Research Group, University of Calabar, Calabar, Nigeria
- Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria
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13
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Slinger CW, Zakery A, Ewen PJ, Owen AE. Photodoped chalcogenides as potential infrared holographic media. Appl Opt 1992; 31:2490-2498. [PMID: 20725175 DOI: 10.1364/ao.31.002490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The extension of holographic techniques from the visible to the infrared is important. Potentially, holographic diffractive elements have a large range of uses in this wave band. Examples include mirrors, lenses, filters, and beam combiners. All these elements would have similar advantages to those enjoyed by their visible band diffractive analogs. The metal photodissolution effect in chalcogenides shows promise as one of the few techniques for producing low-loss holographic materials for use at any given wavelength from 0.6 to beyond 16 microm. To date, the work has concentrated on the photodissolution of silver into arsenic sulfide glasses. Both bulk and surface relief gratings can be fabricated simply by holographic or mask exposure. In principle, kinoforms (e.g., blazed zone plates) and Fresnel lenses can also be made. The results of material studies show that phase gratings with high modulation and low absorption can be produced. A coupled-wave analysis is used to calculate the likely grating performance, and some initial grating characterization results are presented. The limitations of the medium are discussed and possible solutions are considered.
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Hajto J, Owen AE, Gage SM, Snell AJ, LeComber PG, Rose MJ. Quantized electron transport in amorphous-silicon memory structures. Phys Rev Lett 1991; 66:1918-1921. [PMID: 10043343 DOI: 10.1103/physrevlett.66.1918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
This article is intended for behavioral and biomedical researchers who have become involved increasingly in health promotion research in social settings. It describes how researchers may more precisely plan and profit from employing formative evaluation, which is too frequently more casually undertaken than is summative evaluation. Formative evaluation includes responses from the student subjects of such programs and school administrative and instructional staff, as well as other elements unique to the school setting such as existing curricula and the logistics of time and space. In order to tailor such programs to the unique properties of the school setting, a continual feedback loop should be in place. Such loops can channel both quantitative and qualitative data to the researcher to assist in adapting projects to changing conditions during the course of their implementation. This article presents a case history of the application of formative evaluation drawn from a health promotion project conducted by the authors. It includes as background for this case history, definitions of formative evaluation and an analysis of its costs.
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Affiliation(s)
- R I Evans
- Department of Psychology, University of Houston, Texas 77004
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