Experimental studies and DFT calculations to predict atomic arrangements at twin boundaries and distribution behaviors of different solutes in complex intermetallics

2021 ◽  
pp. 110453
Author(s):  
Huixin Jin ◽  
Jianxin Zhang ◽  
Wenyang Zhang ◽  
Youjian Zhang ◽  
Shiyu Ma ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Studies ◽  
Twin Boundaries

Tropylium Salt Promoted Hydroboration Reactions: Mechanistic Insights via Experimental and Computational Studies

2021 ◽  
Author(s):  
Nhan Nu Hong Ton ◽  
Binh Khanh Mai ◽  
Thanh Vinh Nguyen
Keyword(s):  
Dft Calculations ◽  
Lewis Acids ◽  
Experimental Studies ◽  
Cross Coupling ◽  
Computational Studies ◽  
Metal Free ◽  
Hydride Abstraction ◽  
Novel Method ◽  
Tropylium Salts

Abstract: Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross coupling chemistry. This type of reaction has traditionally been mediated by transition metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to efficiently promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic paradigm, which is triggered by a hydride abstraction of pinacolborane with tropylium ion. This is followed by a series of <i>in situ</i> counterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.

scholarly journals Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

2014 ◽  
Vol 10 ◽  
pp. 1896-1905 ◽  
Author(s):  
Alexander F Khlebnikov ◽  
Mikhail S Novikov ◽  
Yelizaveta G Gorbunova ◽  
Ekaterina E Galenko ◽  
Kirill I Mikhailov ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Studies ◽  
Diazo Compounds ◽  
Stationary Points ◽  
Reaction Intermediates ◽  
Reaction Conditions ◽  
Open Chain ◽  
Isoxazole Ring ◽  
Diazo Esters ◽  
Probable Reaction

Theoretical and experimental studies of the reaction of isoxazoles with diazo compounds show that the formation of 2H-1,3-oxazines proceeds via the formation of (3Z)-1-oxa-5-azahexa-1,3,5-trienes which undergo a 6π-cyclization. The stationary points corresponding to the probable reaction intermediates, isoxazolium N-ylides, were located by DFT calculations at the B3LYP/6-31G(d) level only for derivatives without a substituent in position 3 of the isoxazole ring. These isoxazolium N-ylides are thermodynamically and kinetically very unstable. According to the calculations and experimental results 2H-1,3-oxazines are usually more thermodynamically stable than the corresponding open-chain isomers, (3Z)-1-oxa-5-azahexa-1,3,5-trienes. The exception are oxaazahexatrienes derived from 5-alkoxyisoxazoles, which are thermodynamically more stable than the corresponding 2H-1,3-oxazines. Therefore, the reaction of diazo esters with 5-alkoxyisoxazoles is a good approach to 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes. The reaction conditions for the preparation of aryl- and halogen-substituted 2H-1,3-oxazines and 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes from isoxazoles were investigated.

Vibrational Spectra of Triiodomesitylene: Combination of DFT Calculations and Experimental Studies. Effects of the Environment

2008 ◽  
Vol 112 (44) ◽  
pp. 11124-11141 ◽  
Author(s):  
Jean J. Meinnel ◽  
Ali Boudjada ◽  
Abdou Boucekkine ◽  
Fahima Boudjada ◽  
Alain Moréac ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Vibrational Spectra ◽  
Experimental Studies

scholarly journals Relativistic DFT and experimental studies of mono- and bis-actinyl complexes of an expanded Schiff-base polypyrrole macrocycle

2016 ◽  
Vol 45 (40) ◽  
pp. 15910-15921 ◽  
Author(s):  
Xiu-Jun Zheng ◽  
Nicola L. Bell ◽  
Charlotte J. Stevens ◽  
Yu-Xi Zhong ◽  
Georg Schreckenbach ◽  
...  
Keyword(s):  
Schiff Base ◽  
Dft Calculations ◽  
Experimental Studies ◽  
Redox Properties ◽  
Relativistic Dft

Relativistic DFT calculations present accurate geometries of complexes and redox properties, confirmed by the newly-developed experimental syntheses.

scholarly journals Iodine Catalyzed Synthesis of Substituted Furans and Pyrans: Reaction Scope and Mechanistic Insights

2020 ◽  
Author(s):  
Domenic Pace ◽  
Raphaël Robidas ◽  
Uyen P. N. Tran ◽  
Claude Legault ◽  
Thanh Vinh Nguyen
Keyword(s):  
Natural Products ◽  
Dft Calculations ◽  
Ambient Temperature ◽  
Experimental Studies ◽  
Molecular Iodine ◽  
Biologically Active ◽  
Catalytic Method ◽  
Solvent Free Conditions ◽  
High Level ◽  
Substituted Furans

Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically-active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described herein is performed in solvent-free conditions in ambient temperature and atmosphere, thus offering a facile and green alternative to currently available reaction protocols. A combination of experimental studies and high‐level DFT calculations revealed interesting mechanistic insights of this seemingly simple reaction.

scholarly journals Direct Orange 26 Dye Environmental Degradation: Experimental Studies (UV, Mass and Thermal) in Comparison With Computational Exploration Hydrogen Bonding Analysis of TD-DFT Calculations

2021 ◽  
Author(s):  
Zahraa A. M. Abo-Ayad ◽  
Mohamed A. Zayed ◽  
Mahmoud A Noamaan
Keyword(s):  
Hydrogen Bonding ◽  
Dft Calculations ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Population Analysis ◽  
Experimental Studies ◽  
Calculated Data ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Td Dft

Abstract The importance of this study stems from, it concentrates on new approach applying both practical and theoretical aspects to study structure stability of Direct orange dye 26 (DO26) as an important dye widely used for dyeing of cotton or viscose for red orange direct printing. The stable dyes are so difficult to remove, decolorized and/ or degrade, in pure solution or in wastewater samples, without using powerful removal environmental techniques electrochemical oxidations suggest and efficiently used in our Lab. Therefore, it is very important to compare between practical thermal and mass results as efficient techniques in studying dye stability, in comparison with theoretical results using Gaussian program for structural stability identification of DO26 dye, via careful inspection of various phenomena detected in its two symmetrical arms around urea center. Direct orange dye 26 (DO26) structure has been studied applying both practical spectroscopic and theoretical investigations. DFT-B3LYP/6-311++G(d,p) calculations and the electronic vibrational properties are performed to investigate its structure stability and consequently its degradation and removal from its environmental media. Correlation is found between experimental and calculated data. An intra-molecular hydrogen bonding interaction had been detected and characterized in dye skeleton. The hydrogen bonding present in the dye structure affecting its vibrational properties had been discussed. Natural population analysis like HOMO and LUMO and high quality molecular electrostatic potential plots along with various electronics had been presented at the same level of theory. Chemical reactivity descriptors from conceptual density functional theory point of view, structure activity relationship descriptor were obtained. The experimental UV/Visible, FT-IR, mass and GC-mass spectral data of the dye DO26 (D1) had been presented. These data had been supported by TD-DFT calculations to simulate the experimental spectra with computing the natural transition orbitals (NTO) and the orbital composition. The variation of charge transfer length (Δr) and variation in its dipole moment with respect to ground state (ΔmCT) had been computed in order to study the charge redistribution due to the excitations. Actually there is a problem that, degradation of this dye in wastewater by different techniques leads to various unknown fragments but on using theoretical possibilities it can be expected what happened in practical work.

scholarly journals Determination of optimal feed profile in semi-batch reactor: DFT and experimental studies on a Case Study of parallel and serial reactions take place

2021 ◽  
Author(s):  
Bugra AKMAN ◽  
Omur ARAS ◽  
Yunus KAYA
Keyword(s):  
Bisphenol A ◽  
Dft Calculations ◽  
Density Functional ◽  
Batch Reactor ◽  
Experimental Studies ◽  
Basis Set ◽  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Acetone Concentration ◽  
By Products

Semi-batch reactor systems can be used at different areas due to its advantages of the feed manipulation. Common practices are temperature control of the exothermic reactions or selectivity adjustment of the production process include serial and parallel reactions. Bisphenol A (BPA) is theoretically synthesized with 2 moles of phenol and 1 mol of acetone. During the reaction, a stoichiometric ratio or high acetone concentration causes the formation of by-products. This situation has been confirmed by density functional theory (DFT) calculations. In these calcula-tions, the B3LYP method and the 6-311++G(d, p) basis set were used. DFT calculations show that by-products can be formed in the synthesis of bisphenol a. The common method used to solve the by-product problem is to work with high molar phenol/acetone ratios. But this brings additional operating and investment costs. In this study, semi-batch reaction experiments were performed which stoichiometric acetone was fed in reactor with various pulsed modes in the presence of homogenous and heterogonous catalysts. Time versus conversion and selectivity data were collected at various catalyst concentrations. All runs were compared with the results of batch and semi-batch runs performed in over molar ratio of phenol/acetone. As a result, it has been shown that high conversion and selectivity can be achieved by providing energy efficiency with pulsed mode semi batch reactor.

The use of image symmetry in the analysis of high-resolution image of grain boundaries in GaAs

1988 ◽  
Vol 46 ◽  
pp. 594-595
Author(s):  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Experimental Studies ◽  
Diamond Structure ◽  
Sphalerite Structure ◽  
Twin Boundaries ◽  
Group V ◽  
Group Iii ◽  
The Past ◽  
Tilt Boundaries ◽  
The Common

Atomic arrangements at grain boundaries in diamond-structure materials have in the past been theoretically examined most fully for the case of symmetrical interfaces. In particular, <110> tilt boundaries have been modelled in terms of a combination of units corresponding to a/2 [110] edge dislocation cores and symmetrical six-membered rings. Grain boundaries in materials with the sphalerite-structure have two different atomic arrangement for each corresponding grain boundary in the diamond-structure materials; these depend on the relative positions of group III and group V elements. Experimental studies have been carried out recently for twin boundaries, high-angle boundaries and low-angle boundaries of GaAs. This paper illustrates how the analysis of the atomic structure of grain boundaries in GaAs can be facilitated by using the symmetry of HREM images of neighboring Σ=3 coherent twin boundaries in a manner similar to that described earlier for individual stacking faults. Details of the sample preparation are described elsewhere. The orientation of the specimen was such that the electron beam was parallel to the common [110] tilt axis.

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