A Study of Reactivity of Model Compounds of Lignin Biopolymer

2021 ◽  
Vol 316 ◽  
pp. 75-80
Author(s):  
Oleg Kh. Karimov ◽  
Galina Yu. Kolchina ◽  
Eldar M. Movsumzade
Keyword(s):  
Aromatic Ring ◽  
Quantum Chemical ◽  
Density Functional ◽  
Nucleophilic Attack ◽  
Hydroxyl Group ◽  
Model Compounds ◽  
Hartree Fock ◽  
Quantitative Characteristics ◽  
Derivatives Of ◽  
Hybrid Density Functional

In the framework of method of the B3LYP hybrid density functional and the restricted Hartree-Fock method, quantum-chemical calculations of model compounds of lignin, i.e. derivatives of p-hydroxycinnamic alcohol were carried out. The structures and reactivity of coumaric, coniferyl and synapol alcohols were studied. Quantitative characteristics of the reactivity of these acids are given. It is found that the electronic structure of lignin is determined primarily by the charge distribution in its structural phenylpropane unit. In the molecules of all model compounds of lignin, the center for nucleophilic attack is the carbon of aromatic ring (E-ring) with a hydroxyl group, and in the molecule of synapol alcohol, this center is also the carbon of the aromatic ring (E-ring) with a methoxy group. In all three compounds, a center with an increased electron density appears on the Сβ carbon atom.

scholarly journals The study of the reactivity of derivatives of hydroxycinnamic alcohol as model compounds of lignin

2020 ◽  
Vol 61 (1) ◽  
pp. 33-39
Author(s):  
Oleg K. Karimov ◽  
◽  
Galina Yu. Kolchina ◽  
Eldar M. Movsumzade ◽  
◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Density Functional ◽  
Nucleophilic Attack ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Model Compounds ◽  
Hartree Fock ◽  
A Charge ◽  
Derivatives Of ◽  
Hybrid Density Functional

In the framework of method of the B3LYP hybrid density functional and the restricted Hartree-Fock method in the basis of 6-311 (d, p), quantum-chemical calculations of model compounds of lignin, i.e. derivatives of p-hydroxycinnamic alcohol were carried out. The structures and reactivity of coumaric, coniferyl and synapol alcohols were studied. The structural units of lignin contain hydroxyl groups which can be in the plane of benzene ring but can be turned up to 90° with respect to this plane. In the case of methoxy groups which are also present in coniferol and synapol alcohols, the methyl group is turned to 90° with respect to the plane of ring, as the most favorable conformation. Moreover, these compounds contain π,π-conjugations of the aromatic ring with an aliphatic fragment of molecule that affects the geometric characteristics of the molecule. For coumaric and coniferyl alcohols, the Сар–Сα bond length is 1.47 Ǻ. A slight deformation of valence angles for coumaric and synapol alcohols equal to 118.94° and 117.72° respectively instead of 120° at sp2 hybridization indicates the availability of conjugation. The use of a charge as a descriptor of attack selectivity of nucleophilic and electrophilic particles allows us to analized of the reactivity of these acids are given. It is found that the electronic structure of lignin is determined primarily by the charge distribution in its structural phenylpropane unit. In the molecules of all model compounds of lignin, the center for nucleophilic attack is the carbon of aromatic ring (E-ring) with a hydroxyl group, and in the molecule of synapol alcohol, this center is also the carbon of the aromatic ring (E-ring) with a methoxy group. In all three compounds, a center with an increased electron density appears on the Сβ carbon atom.

Periodic Hartree–Fock and hybrid density functional calculations on the metallic and the insulating phase of (EDO-TTF)2PF6

2015 ◽  
Vol 17 (45) ◽  
pp. 30371-30377 ◽  
Author(s):  
Gerrit-Jan Linker ◽  
Paul H. M. van Loosdrecht ◽  
Piet Th. van Duijnen ◽  
Ria Broer
Keyword(s):  
Phase Transition ◽  
Quantum Chemical ◽  
Density Functional ◽  
Electronic Band ◽  
Metal Insulator ◽  
Hartree Fock ◽  
Insulator Phase Transition ◽  
Insulating Phase ◽  
Electronic Band Structures ◽  
Hybrid Density Functional

Electronic band structures obtained from quantum chemical calculations are used to discuss the metal–insulator phase transition in (EDO-TTF)2PF6 in terms of a Peierls mechanism.

Theoretical Study of the Process of Passage of Glycoside Amides through the Cell Membrane of Cancer Cell

2020 ◽  
Vol 20 ◽  
Author(s):  
Vasil Tsanov ◽  
Hristo Tsanov
Keyword(s):  
Cell Membrane ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Quantum Chemical ◽  
Density Functional ◽  
Enzyme Regulation ◽  
Amide Derivatives ◽  
Pass Through ◽  
Hydrolysis Of ◽  
Derivatives Of

Background:: This article concentrates on the processes occurring in the medium around the cancer cell and the transfer of glycoside amides through their cell membrane. They are obtained by modification of natural glycoside-nitriles (cyano-glycosides). Hydrolysis of starting materials in the blood medium and associated volume around physiologically active healthy and cancer cells, based on quantum-chemical semi-empirical methods, is considered. Objective:: Based on the fact that the cancer cell feeds primarily on carbohydrates, it is likely that organisms have adapted to take food containing nitrile glycosides and / or modified forms to counteract "external" bioactive activity. Cancers, for their part, have evolved to create conditions around their cells that eliminate their active apoptotic forms. This is far more appropriate for them than changing their entire enzyme regulation to counteract it. In this way, it protects itself and the gene sets and develops according to its instructions. Methods:: Derived pedestal that closely defines the processes of hydrolysis in the blood, the transfer of a specific molecular hydrolytic form to the cancer cell membrane and with the help of time-dependent density-functional quantum- chemical methods, its passage and the processes of re-hydrolysis within the cell itself, to forms causing chemical apoptosis of the cell - independent of its non-genetic set, which seeks to counteract the process. Results:: Used in oncology it could turn a cancer from a lethal to a chronic disease (such as diabetes). The causative agent and conditions for the development of the disease are not eliminated, but the amount of cancer cells could be kept low for a long time (even a lifetime). Conclusion:: The amide derivatives of nitrile glycosides exhibit anti-cancer activity, the cancer cell probably seeks to displace hydrolysis of these derivatives in a direction that would not pass through its cell membrane and the amide- carboxyl derivatives of nitrile glycosides could deliver extremely toxic compounds within the cancer cell itself and thus block and / or permanently damage its normal physiology.

scholarly journals The crystalline structure of SrRuO3: Application of hybrid scheme to the density functionals revised for solids

2017 ◽  
Vol 57 (2) ◽  
Author(s):  
Šarūnas Masys ◽  
Valdas Jonauskas
Keyword(s):  
Crystalline Structure ◽  
Density Functional ◽  
Theoretical Modelling ◽  
Density Functionals ◽  
Hybrid Scheme ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Hartree Fock ◽  
Hybrid Density Functional ◽  
Theory Scheme

The crystalline structure of ground-state orthorhombic SrRuO3 is reproduced by applying the hybrid density functional theory scheme to the functionals based on the revised generalized-gradient approximations for solidstate calculations. The amount of Hartree–Fock (HF) exchange energy is varied in the range of 5–20% in order to systematically ascertain the optimum value of HF mixing which in turn ensures the best correspondence to the experimental measurements. Such investigation allows one to expand the set of tools that could be used for the efficient theoretical modelling of, for example, only recently stabilized phases of SrRuO3, helping to resolve issues emerging for the experimentalists.

Al-doped graphene as an effective adsorber for some toxic derivatives of aromatic hydrocarbons

2017 ◽  
Vol 16 (01) ◽  
pp. 1750004 ◽  
Author(s):  
Min Ji ◽  
Xinlu Cheng ◽  
Weidong Wu
Keyword(s):  
Charge Transfer ◽  
Aromatic Hydrocarbons ◽  
Adsorption Energy ◽  
Density Functional ◽  
Hydroxyl Group ◽  
The Density Functional Theory ◽  
Doped Graphene ◽  
Perfect Graphene ◽  
Hydrocarbons Adsorption ◽  
Derivatives Of

The density functional theory (DFT) was used to investigate some toxic derivatives of aromatic hydrocarbons adsorption on perfect graphene (pG) and graphene-doped with B/Al/Ga (BG/AlG/GaG). And the parallel and vertical adsorptions were considered for the position relation between the adsorbent and adsorbate. The adsorption energy, adsorption distance, charge transfer and density of states (DOS) were discussed in optimized structures. The greater adsorption energy, shorter adsorption distance and more charge transfer were found in AlG by studying the four kinds of molecules (phenol/m-cresol/PCP/p-NP) adsorption on pG/BG/AlG/GaG. Then, 10 derivatives adsorption on AlG were reported, and the adsorption energy increased in the order of pentachlorophenol [Formula: see text] 2,4,6-trichlorophenol [Formula: see text] 2,4-dichlorophenol [Formula: see text] p-cresol [Formula: see text] m-cresol [Formula: see text] phenol [Formula: see text] o-chlorophenol [Formula: see text] o-cresol [Formula: see text] 2,4,6-trintrotoluene [Formula: see text] para-nitrophenol. The interaction between these derivatives and the substrate was chemisorption for AlG and physisorption for pG. The oxygen atom in nitro group was more closer to the substrate than in hydroxyl group about optimized structures.

Prediction of the photoelectron spectrum for XPY2 (X = H, F, Cl; Y = O, S) type of molecules by ab initio and DFT methods

2006 ◽  
Vol 84 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Didier Bégué ◽  
Jean-marc Sotiropoulos ◽  
Claude Pouchan ◽  
Daisy Y Zhang
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Radical Cations ◽  
Dft Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Orbital Energies ◽  
Koopmans Theorem ◽  
Vertical Ionization Potentials ◽  
Hybrid Density Functional

The present study reports the theoretical vertical ionization potentials (IPs) for all the valence electrons in six XPY2 molecules by utilizing the corrected orbital energies calculated with three theoretical methods, namely, the ab initio Hartree–Fock (HF), and both the pure and hybrid density functional theory (DFT) methods at, respectively, the BLYP/6-311+G* and B3lYP/6-311+G* levels of theory. Evaluation of the numerical corrections to the orbital energies was achieved by comparisons with the IP values obtained via explicit computation of the energy differences between the neutral molecules and the corresponding radical cations (the ΔSCF method) and shows values from –0.9 to –1.9 eV for the HF, and positive values from 2.9 to 3.9 eV and from 1.8 to 2.4 eV for the pure and hybrid DFT methods, respectively. In contrast to the orbital energies, the ΔSCF method is shown to give consistent values among the three methods, as well as reasonable agreement with the experimental IP values.Key words: ionization potential, phosphorane, Koopmans' theorem, Janak's theorem.

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