scholarly journals Application of computational chemistry in chemical reactivity: a review

2021 ◽  
Author(s):  
C. W. Chidiebere ◽  
C. E. Duru ◽  
J. P. C. Mbagwu
Keyword(s):  
Computational Chemistry ◽  
Molecular Orbital ◽  
Chemical Reactions ◽  
Quantum Physics ◽  
Chemical Reactivity ◽  
Chemical Change ◽  
Molecular Orbitals ◽  
Automatic Data ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Molecular orbitals are vital to giving reasons several chemical reactions occur. Although, Fukui and coworkers were able to propose a postulate which shows that highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) is incredibly important in predicting chemical reactions. It should be kept in mind that this postulate could be a rigorous one therefore it requires an awfully serious attention in order to be understood. However, there has been an excellent breakthrough since the introduction of computational chemistry which is mostly used when a mathematical method is fully well built that it is automated for effectuation and intrinsically can predict chemical reactivity. At the cause of this review, we’ve reported on how HOMO and LUMO molecular orbitals may be employed in predicting a chemical change by the utilization of an automatic data processing (ADP) system through the utilization of quantum physics approximations.

Perspectives on the Role of the Frontier Effective-for-Reaction Molecular Orbital (FERMO) in the Study of Chemical Reactivity: An Updated Review

2020 ◽  
Vol 24 (3) ◽  
pp. 314-331 ◽  
Author(s):  
Letícia S. Braga ◽  
Daniel H. S. Leal ◽  
Kamil Kuca ◽  
Teodorico C. Ramalho
Keyword(s):  
Molecular Orbital ◽  
Chemical Reactions ◽  
Chemical Reactivity ◽  
Molecular Orbitals ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Molecular orbitals are critical in the rationalization of several chemical reactions. Thus, the frontier molecular orbital theory, proposed by Fukui's group, postulated the importance of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) for chemical reactions. It should be kept in mind, however, that there are limitations of this theory and new perspectives about the chemical reactivity have recently been arisen based on composition and location of other frontier molecular orbitals. In this review, we have reported the development and the most recent applications of the Frontier Effective-for-Reaction Molecular Orbital (FERMO) concept, which describes the breaking and formation of new chemical bonds and can in turn, provide important clues that modulate chemical reactivity of atoms and molecules.

scholarly journals Electronic Properties of Triangle Molybdenum Disulfide (MoS2) Clusters with Different Sizes and Edges

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1157
Author(s):  
Songsong Wang ◽  
Changliang Han ◽  
Liuqi Ye ◽  
Guiling Zhang ◽  
Yangyang Hu ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Electronic Properties ◽  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Structures ◽  
Edge States ◽  
Frontier Orbitals ◽  
Edge Structure ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The electronic structures and transition properties of three types of triangle MoS2 clusters, A (Mo edge passivated with two S atoms), B (Mo edge passivated with one S atom), and C (S edge) have been explored using quantum chemistry methods. The highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of B and C is larger than that of A, due to the absence of the dangling of edge S atoms. The frontier orbitals (FMOs) of A can be divided into two categories, edge states from S3p at the edge and hybrid states of Mo4d and S3p covering the whole cluster. Due to edge/corner states appearing in the FMOs of triangle MoS2 clusters, their absorption spectra show unique characteristics along with the edge structure and size.

scholarly journals Photoconductivity of Low-Bandgap Polymer and Polymer: Fullerene Bulk Heterojunction Studied by Constant Photocurrent Method

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
V. V. Malov ◽  
A. R. Tameev ◽  
S. V. Novikov ◽  
M. V. Khenkin ◽  
A. G. Kazanskii ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Bulk Heterojunction ◽  
Inorganic Materials ◽  
Fullerene Derivative ◽  
Approximation Procedure ◽  
Photoelectric Properties ◽  
Highest Occupied Molecular Orbital ◽  
Donor Acceptor ◽  
Lowest Unoccupied Molecular Orbital ◽  
Doped Polymers

AbstractOptical and photoelectric properties of modern photosensitive polymers are of great interest due to their prospects for photovoltaic applications. In particular, an investigation of absorption and photoconductivity edge of these materials could provide valuable information. For these purpose we applied the constant photocurrent method which has proved its efficiency for inorganic materials. PCDTBT and PTB7 polymers were used as objects for the study as well as their blends with a fullerene derivative PC71BM. The measurements by constant photocurrent method (CPM) show that formation of bulk heterojunction (BHJ) in the blends increases photoconductivity and results in a redshift of the photocurrent edge in the doped polymers compared with that in the neat polymers. Obtained from CPM data, spectral dependences of absorption coefficient were approximated using Gaussian distribution of density-of-states within HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) bands. The approximation procedure allowed us to evaluate rather optical than electrical bandgaps for the studied materials. Moreover, spectra of polymer:PC71BM blends were fitted well by the sum of two Gaussian peaks which reveal both the transitions within the polymer and the transitions involving charge transfer states at the donor-acceptor interface in the BHJ.

scholarly journals Estudo do comportamento óptico-estrutural do LiNbO3

Cerâmica ◽  
2003 ◽  
Vol 49 (309) ◽  
pp. 36-39 ◽  
Author(s):  
C. D. Pinheiro ◽  
V. Bouquet ◽  
F. M. Pontes ◽  
E. R. Leite ◽  
E. Longo
Keyword(s):  
Molecular Orbital ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Realizou-se um estudo teórico-experimental sobre as estruturas cristalina e amorfa de niobato de lítio, para verificar a influência dos defeitos sobre as propriedades ópticas desse semicondutor. Filmes finos cristalinos de LiNbO3 (c-LN) e amorfo (a-LN) foram preparados pelo método dos precursores poliméricos, sendo caracterizados por difração de raios X e microscopia de força atômica. As propriedades ópticas foram estudadas por UV-Visível e espectroscopia Raman. Em particular, o filme amorfo apresentou luminescência, cuja posição do pico varia de acordo com o comprimento de onda de excitação. A diferença de energia entre os níveis HOMO (Highest Occupied Molecular Orbital) e LUMO (Lowest Unoccupied Molecular Orbital) revela que o gap de banda da fase cristalina é maior que aquele exibido pela fase amorfa, em acordo com os dados experimentais de UV-visível. Observou-se o surgimento de novos níveis eletrônicos na região do gap de banda na estrutura amorfa, este fato pode explicar as propriedades ópticas particulares observadas sobre o filme amorfo.

Synthesis and characterization of oligo-4-[(pyridin-3-ylimino)methyl]phenol

2007 ◽  
Vol 61 (3) ◽  
Author(s):  
İ. Kaya ◽  
S. Çulhaoğlu ◽  
D. Şenol
Keyword(s):  
Molecular Orbital ◽  
Thermal Analyses ◽  
Size Exclusion ◽  
Degradation Temperature ◽  
Highest Occupied Molecular Orbital ◽  
N2 Atmosphere ◽  
Exclusion Chromatography ◽  
N Doping ◽  
Lowest Unoccupied Molecular Orbital ◽  
Optimum Reaction

AbstractThe oxidative polycondensation of 4-[(pyridin-3-ylimino)methyl]phenol (4-PIMP) with O2, H2O2, and NaOCl was studied in an aqueous alkaline medium between 50°C and 90°C. Oligo-4-[(pyridin-3-ylimino)methyl]phenol (O-4-PIMP) prepared was characterized by 1H-NMR, 13C-NMR, FT-IR, UV-VIS, size-exclusion chromatography, and elemental and thermal analyses techniques. At the optimum reaction conditions, the yield of O-4-PIMP was 18.9%, 39.4%, and 46.8% using H2O2, O2, and NaOCl oxidant, respectively. According to the TG analysis, the initial degradation temperature of O-4-PIMP was 218°C, which was by 50°C higher than that of 4-PIMP. Thermal analyses of 4-PIMP and O-4-PIMP were carried out in N2 atmosphere at 15–1000°C. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, and electrochemical energy gaps of 4-PIMP and O-4-PIMP were determined from the onset potentials for n-doping and p-doping, respectively. Also, optical band gaps of 4-PIMP and O-4-PIMP were determined according to UV-VIS measurements.

scholarly journals QTAIM investigation of bis(pyrazol-1-yl)methane derivative and its Zn(II) complexes (ZnLX2, X=Cl, Br or I)

2015 ◽  
Vol 80 (8) ◽  
pp. 997-1008 ◽  
Author(s):  
Maryam Dehestani ◽  
Leila Zeidabadinejad
Keyword(s):  
Molecular Orbital ◽  
Critical Points ◽  
Structural Parameters ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Theory Approach ◽  
Topological Parameters ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Topological analyses of the electron density using the quantum theory of atoms in molecules (QTAIM) have been carried out at the B3PW91/6-31g (d) theoretical level, on bis(pyrazol-1-yl)methanes derivatives 9-(4-(di (1H-pyrazol-1-yl)-methyl)phenyl)-9H-carbazole (L) and its zinc(II) complexes: ZnLCl2 (1), ZnLBr2 (2) and ZnLI2 (3). The topological parameters derived from Bader theory were also analyzed; these are characteristics of Zn-bond critical points and also of ring critical points. The calculated structural parameters are the frontier molecular orbital energies highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), hardness (?), softness (S), the absolute electronegativity (?), the electrophilicity index (?) and the fractions of electrons transferred (?N) from ZnLX2 complexes to L. The numerous correlations and dependencies between energy terms of the Symmetry Adapted Perturbation Theory approach (SAPT), geometrical, topological and energetic parameters were detected and described.

scholarly journals Emphasizing the Operational Role of a Novel Graphene-Based Ink into High Performance Ternary Organic Solar Cells

2019 ◽  
Author(s):  
Minas M. Stylianakis ◽  
Dimitriοs M. Kosmidis ◽  
Katerina Anagnostou ◽  
Christos Polyzoidis ◽  
Miron Krassas ◽  
...  
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Organic Solar Cells ◽  
High Performance ◽  
Energy Levels ◽  
Fullerene Derivative ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
Synthetic Routes

A novel solution-processed graphene-based material was synthesized by treating graphene oxide (GO) with 2,5,7-trinitro-9-oxo-fluorenone-4-carboxylic acid (TNF-COOH) moieties, via simple synthetic routes. The yielded molecule N-[(carbamoyl-GO)ethyl]-N’-[(carbamoyl)-(2,5,7-trinitro-9-oxo-fluorene)] (GO-TNF) was thoroughly characterized and it was shown that it presents favorable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels to function as a bridge component between the polymeric donor poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl}) (PTB7) and the fullerene derivative acceptor [6,6]-phenyl-C71-butyric-acid-methylester (PC71BM). In this context, a GO-TNF based ink was prepared and directly incorporated within the binary photoactive layer, in different volume ratios (1-3% ratio to the blend), for the effective realization of inverted ternary organic solar cells (OSCs) of the structure ITO/PFN/PTB7:GO-TNF:PC71BM/MoO3/Al. The addition of 2% v/v GO-TNF ink led to a champion power conversion efficiency (PCE) of 8.71% that was enhanced by ~13% as compared to the reference cell.

scholarly journals Computational Aspects of (E)-O-Carbomethoxy Methyl Oxime Ether of 1,3-Dimethyl-2,6-Diphenylpiperidin-4-One

2019 ◽  
Vol 9 (2S2) ◽  
pp. 701-706
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Atomic Charge ◽  
Molecular Geometry ◽  
Biologically Active ◽  
Oxime Ether ◽  
Structure And Property ◽  
Highest Occupied Molecular Orbital ◽  
Computational Aspects ◽  
Lowest Unoccupied Molecular Orbital

Density Functional Theoretical (DFT) studies on the biologically active oxime ether derived from 1,3-dimethyl-2,6-diphenylpiperidin-4-one has been carried out. Various quantum chemical parameters of the molecule viz. molecular geometry, Highest Occupied Molecular Orbital – Lowest Unoccupied Molecular Orbital (HOMO–LUMO) energies, Non-Linear Optical (NLO) properties, Mulliken atomic charge distribution were obtained theoretically and compared with the single crystal data. An insight into the structure and property correlation revealed the probable behavior of the molecule studied

Computational and Experimental Study onthe Adsorption and Inhibition Effects of 1,3-Benzothiazol-6-ol on the Corrosion ofSteel X80 in Acidic Solution

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Iman Danaee ◽  
Paria Nikparsa ◽  
Mohammad Reza Khosravi-Nikou
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Acidic Solution ◽  
Energy Gap ◽  
Force Microscopy ◽  
Highest Occupied Molecular Orbital ◽  
Low Concentrations ◽  
Noise Data ◽  
Chemical Factors ◽  
Lowest Unoccupied Molecular Orbital

Abstract In this work, the adsorption and inhibition behavior of 1,3-benzothiazol-6-ol were investigated by computational and experimental techniques for steel X80 corrosion in acidic solution. The density functional theory was carried out and quantum chemical factors like the energy gap, energy of highest occupied molecular orbital, the energy of lowest unoccupied molecular orbital, the fraction of electron transferred, and Mulliken charges have been calculated. In addition, according to quantum calculation, S atom in 1,3-benzothiazol-6-ol indicated more tendency for electrophilic attack in adsorption. The main reason for high inhibition efficiencies in very low concentrations is the planar and simplicity of inhibitor structure which leads to increasing the efficiency of adsorption by functional group especially sulfur. Electrochemical frequency modulation and potentiodynamic polarization indicated that this material has excellent inhibiting features in very low concentrations. The influence of DC trend on the explanation of electrochemical noise data was evaluated by polynomial fitting and the optimum polynomial order m = 5 was obtained. Noise resistance and the inhibition efficiency was calculated and compared in different methods. The theory of shot noise in frequency domain was used to obtain the electrochemical event charge. The corroded surface of steel in the absence and existence of thiazole compound was studied by Atomic force microscopy.

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