New Insights into the Nature of the Band Gap of CuGeO3 Nanoparticles: Synthesis, Electronic Structure, and Optical and Photocatalytic Properties

We report, for the first time, new insights into the nature of the band gap of <a>CuGeO3 </a>(CGO) nanocrystals synthesized from a microwave-assisted hydrothermal method in the presence of citrate. To the best of our knowledge, this synthetic approach has the shortest reaction time and it works at the lowest temperatures reported in the literature for the preparation of these materials. The influence of the surfactant on the structural, electronic, optical, and photocatalytic properties of CGO nanocrystals is discussed by a combination of experimental and theoretical approaches, and that results elucidates the nature of the band gap of synthetized CGO nanocrystals. We believe that this particular strategy is one of the most critical parameters for the development of innovative applications and that result could shed some light on the emerging material design with entirely new properties.

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Semi-Synthetic Approach Leading to 8-Prenylnaringenin and 6-Prenylnaringenin: Optimization of the Microwave-Assisted Demethylation of Xanthohumol Using Design of Experiments

Molecules ◽

10.3390/molecules25174007 ◽

2020 ◽

Vol 25 (17) ◽

pp. 4007

Author(s):

Corinna Urmann ◽

Herbert Riepl

Keyword(s):

Reaction Time ◽

Lithium Chloride ◽

Biological Effects ◽

Synthetic Approach ◽

Prenylated Flavonoids ◽

Microwave Assisted ◽

Synthesis Strategy ◽

Final Yield ◽

Optimized Conditions ◽

First Time

The isomers 8-prenylnaringenin and 6-prenylnaringenin, both secondary metabolites occurring in hops, show interesting biological effects, like estrogen-like, cytotoxic, or neuro regenerative activities. Accordingly, abundant sources for this special flavonoids are needed. Extraction is not recommended due to the very low amounts present in plants and different synthesis approaches are characterized by modest yields, multiple steps, the use of expensive chemicals, or an elaborate synthesis. An easy synthesis strategy is the demethylation of xanthohumol, which is available due to hop extraction industry, using lithium chloride and dimethylformamide, but byproducts and low yield did not make this feasible until now. In this study, the demethylation of xanthohumol to 8-prenylnaringenin and 6-prenylnaringenin is described the first time and this reaction was optimized using Design of Experiment and microwave irradiation. With the optimized conditions—temperature 198 °C, 55 eq. lithium chloride, and a reaction time of 9 min, a final yield of 76% of both prenylated flavonoids is reached.

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Переход металл-полупроводник в нанопленках иттербия, индуцированный адсорбированными молекулами кислорода

Журнал технической физики ◽

10.21883/jtf.2021.07.50961.18-21 ◽

2021 ◽

Vol 91 (7) ◽

pp. 1189

Author(s):

М.В. Кузьмин ◽

М.А. Митцев

Keyword(s):

Electronic Structure ◽

Crystal Lattice ◽

Band Gap ◽

Scanning Tunneling Spectroscopy ◽

Tunneling Spectroscopy ◽

Quantum States ◽

Scanning Tunneling ◽

Bonding Type ◽

First Time

The influence of nondissociative adsorption of oxygen molecules on the electronic structure of ytterbium films with the thickness of 16 monolayers (6.08 nm) has been studied for the first time by using scanning tunneling spectroscopy. It is established that the adsorption of O2 molecules induces the metal-semiconductor transition in ytterbium. As a result of this transition, the quantum states have disappeared in the films, which evidences for a change of bonding type in the ytterbium crystal lattice, as well as the band gap of ~0.72 eV has opened.

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Doping ofTiO2Polymorphs for Altered Optical and Photocatalytic Properties

International Journal of Photoenergy ◽

10.1155/2009/294042 ◽

2009 ◽

Vol 2009 ◽

pp. 1-22 ◽

Cited By ~ 45

Author(s):

Xiliang Nie ◽

Shuping Zhuo ◽

Gloria Maeng ◽

Karl Sohlberg

Keyword(s):

Optical Properties ◽

Electronic Structure ◽

Photocatalytic Activity ◽

Band Gap ◽

First Principles ◽

Photocatalytic Properties ◽

First Principles Calculations ◽

The Common ◽

Qualitative Picture

This paper reviews recent investigations of the influence of dopants on the optical properties ofTiO2polymorphs. The common undoped polymorphs ofTiO2are discussed and compared. The results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of theTiO2electronic structure, which is supported with first-principles calculations.

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Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20010139 ◽

2001 ◽

Vol 66 (1) ◽

pp. 139-154 ◽

Cited By ~ 11

Author(s):

M. Fátima C. Guedes Da Silva ◽

Luísa M. D. R. S. Martins ◽

João J. R. Fraústo Da Silva ◽

Armando J. L. Pombeiro

Keyword(s):

Cyclic Voltammetry ◽

Electronic Structure ◽

Binding Sites ◽

Closed Shell ◽

Carbonyl Complexes ◽

Metal Centre ◽

Pt Electrode ◽

Metal Site ◽

Oxidation Potentials ◽

First Time

The organonitrile or carbonyl complexes cis-[ReCl(RCN)(dppe)2] (1) (R = 4-Et2NC6H4 (1a), 4-MeOC6H4 (1b), 4-MeC6H4 (1c), C6H5 (1d), 4-FC6H4 (1e), 4-ClC6H4 (1f), 4-O2NC6H4 (1g), 4-ClC6H4CH2 (1h), t-Bu (1i); dppe = Ph2PCH2CH2PPh2), or cis-[ReCl(CO)(dppe)2] (2), as well as trans-[FeBr(RCN)(depe)2]BF4 (3) (R = 4-MeOC6H4 (3a), 4-MeC6H4 (3b), C6H5 (3c), 4-FC6H4 (3d), 4-O2NC6H4 (3e), Me (3f), Et (3g), 4-MeOC6H4CH2 (3h); depe = Et2PCH2CH2PEt2), novel trans-[FeBr(CO)(depe)2]BF4 (4) and trans-[FeBr2(depe)2] (5) undergo, as revealed by cyclic voltammetry at a Pt-electrode and in aprotic non-aqueous medium, two consecutive reversible or partly reversible one-electron oxidations assigned as ReI → ReII → ReIII or FeII → FeIII → FeIV. The corresponding values of the oxidation potentials IE1/2ox and IIE1/2ox (waves I and II, respectively) correlate with the Pickett's and Lever's electrochemical ligand and metal site parameters. This allows to estimate these parameters for the various nitrile ligands, depe and binding sites (for the first time for a FeIII/IV couple). The electrochemical ligand parameter show dependence on the "electron-richness" of the metal centre. The values of IE1/2ox for the ReI complexes provide some supporting for a curved overall relationship with the sum of Lever's electrochemical ligand parameter. The Pickett parametrization for closed-shell complexes is extended now also to 17-electron complexes, i.e. with the 15-electron ReII and FeIII centres in cis-{[ReCl(dppe)2]}+ and trans-{FeBr(depe)2}2+, respectively.

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Improving the ZT of SnTe using electronic structure engineering: unusual behavior of Bi dopant in the presence of Pb as a co-dopant

Materials Advances ◽

10.1039/d1ma00696g ◽

2021 ◽

Vol 2 (19) ◽

pp. 6267-6271 ◽

Cited By ~ 3

Author(s):

U. Sandhya Shenoy ◽

D. Krishna Bhat

Keyword(s):

Electronic Structure ◽

Synergistic Effect ◽

Band Gap ◽

Resonance Level ◽

Unusual Behavior ◽

Level Increase ◽

Structure Engineering

Extraordinary tuning of electronic structure of SnTe by Bi in the presence of Pb as a co-adjuvant dopant. Synergistic effect of resonance level, increase in the band gap, valence and conduction sub-bands convergence leads to enhanced TE performance.

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Electronic structure engineering of tin telluride through co-doping of bismuth and indium for high performance thermoelectrics: a synergistic effect leading to a record high room temperature ZT in tin telluride

Journal of Materials Chemistry C ◽

10.1039/c9tc01184f ◽

2019 ◽

Vol 7 (16) ◽

pp. 4817-4821 ◽

Cited By ~ 19

Author(s):

U. Sandhya Shenoy ◽

D. Krishna Bhat

Keyword(s):

Electronic Structure ◽

Synergistic Effect ◽

Band Gap ◽

High Performance ◽

Room Temperature ◽

Band Offset ◽

Valence Band Offset ◽

Co Doping ◽

Tin Telluride ◽

Structure Engineering

Resonance states due to Bi and In co-doping, band gap enlargement, and a reduced valence-band offset in SnTe lead to a record high room-temperature ZT.

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Gap solitons supported by an optical lattice in biased photorefractive crystals having both the linear and quadratic electro-optic effect

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0075 ◽

2020 ◽

Vol 75 (8) ◽

pp. 749-756

Author(s):

Aavishkar Katti ◽

Chittaranjan P. Katti

Keyword(s):

Band Gap ◽

Optical Lattice ◽

Propagation Constant ◽

Gap Soliton ◽

Electro Optic ◽

Quadratic Nonlinearities ◽

Existence And Stability ◽

Gap Solitons ◽

Finite Band ◽

First Time

AbstractWe investigate the existence and stability of gap solitons supported by an optical lattice in biased photorefractive (PR) crystals having both the linear and quadratic electro-optic effect. Such PR crystals have an interesting interplay between the linear and quadratic nonlinearities. Gap solitons are predicted for the first time in such novel PR media. Taking a relevant example (PMN-0.33PT), we find that the gap solitons in the first finite bandgap are single humped, positive and symmetric solitons while those in the second finite band gap are antisymmetric and double humped. The power of the gap soliton depends upon the value of the axial propagation constant. We delineate three power regimes and study the gap soliton profiles in each region. The gap solitons in the first finite band gap are not linearly stable while those in the second finite band gap are found to be stable against small perturbations. We study their stability properties in detail throughout the finite band gaps. The interplay between the linear and quadratic electro-optic effect is studied by investigating the spatial profiles and stability of the gap solitons for different ratios of the linear and quadratic nonlinear coefficients.

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Quantum algorithm for alchemical optimization in material design

Chemical Science ◽

10.1039/d0sc05718e ◽

2021 ◽

Author(s):

Panagiotis Kl. Barkoutsos ◽

Fotios Gkritsis ◽

Pauline J. Ollitrault ◽

Igor O. Sokolov ◽

Stefan Woerner ◽

...

Keyword(s):

Electronic Structure ◽

Drug Discovery ◽

Chemical Composition ◽

Quantum Algorithm ◽

Material Design ◽

Quantum Mechanical ◽

Near Future

‘Alchemical’ quantum algorithm for the simultaneous optimisation of chemical composition and electronic structure for material design. By exploiting quantum mechanical principles this approach will boost drug discovery in the near future.

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