scholarly journals Straightforward Design for Phenoxy-Imine Catalytic Activity in Ethylene Polymerization: Theoretical Prediction

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 422 ◽  
Author(s):  
Pongsakorn Chasing ◽  
Phornphimon Maitarad ◽  
Hongmin Wu ◽  
Dengsong Zhang ◽  
Liyi Shi ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Catalytic Activity ◽  
Transition Metals ◽  
Density Functional ◽  
Molecular Design ◽  
Predictive Ability ◽  
Orbital Energy ◽  
Total Charge ◽  
Functional Theory ◽  
Qsar Analysis

The quantitative structure-activity relationship (QSAR) of 18 Ti-phenoxy-imine (FI-Ti)-based catalysts was investigated to clarify the role of the structural properties of the catalysts in polyethylene polymerization activity. The electronic properties of the FI-Ti catalysts were analyzed based on density functional theory with the M06L/6-31G** and LANL2DZ basis functions. The analysis results of the QSAR equation with a genetic algorithm showed that the polyethylene catalytic activity mainly depended on the highest occupied molecular orbital energy level and the total charge of the substituent group on phenylimine ring. The QSAR models showed good predictive ability (R2) and R2 cross validation (R2cv) values of greater than 0.927. The design concept is “head-hat”, where the hats are the phenoxy-imine substituents, and the heads are the transition metals. Thus, for the newly designed series, the phenoxy-imine substituents still remained, while the Ti metal was replaced by Zr or Ni transition metals, entitled FI-Zr and FI-Ni, respectively. Consequently, their polyethylene polymerization activities were predicted based on the obtained QSAR of the FI-Ti models, and it is noteworthy that the FI-Ni metallocene catalysts tend to increase the polyethylene catalytic activity more than that of FI-Zr complexes. Therefore, the new designs of the FI-Ni series are proposed as candidate catalysts for polyethylene polymerization, with their predicted activities in the range of 35,000–48,000 kg(PE)/mol(Cat.)·MPa·h. This combined density functional theory and QSAR analysis is useful and straightforward for molecular design or catalyst screening, especially in industrial research.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation

2017 ◽  
Vol 19 (33) ◽  
pp. 22344-22354 ◽  
Author(s):  
Sajjad Ali ◽  
Tian Fu Liu ◽  
Zan Lian ◽  
Bo Li ◽  
Dang Sheng Su
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Catalytic Activity ◽  
Carbon Nanotube ◽  
Reaction Mechanism ◽  
Co Oxidation ◽  
Density Functional ◽  
Functional Theory ◽  
Single Walled Carbon Nanotube ◽  
Wales Defect

The mechanism of CO oxidation by O2 on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory.

scholarly journals A Free Aluminylene with Diverse σ-Donating and Doubly σ/π-Accepting Ligand Features for Transition Metals

2021 ◽  
Author(s):  
Xin Zhang ◽  
Liu Leo Liu
Keyword(s):  
Density Functional Theory ◽  
Coordination Chemistry ◽  
Transition Metals ◽  
Electronic Structures ◽  
Ligand Exchange ◽  
Density Functional ◽  
Reduction Reaction ◽  
Functional Theory ◽  
Metal Centers ◽  
Coordination Behavior

We report herein the synthesis, characterization, and coordination chemistry of a free N-aluminylene, namely a carbazolylaluminylene 2b. This species is prepared via a reduction reaction of the corresponding carbazolyl aluminium diiodide. The coordination behavior of 2b towards transition metal centers (W, Cr) is shown to afford a series of novel aluminylene complexes 3-6 with diverse coordination modes. We demonstrate that the Al center in 2b can behave as: 1. a σ-donating and doubly π-accepting ligand; 2. a σ-donating, σ-accepting and π-accepting ligand; and 3. a σ-donating and doubly σ-accepting ligand. Additionally, we show ligand exchange at the aluminylene center providing access to the modulation of electronic properties of transition metals without changing the coordinated atoms. Investigations of 2b with IDippCuCl (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) show an unprecedented aluminylene-alumanyl transformation leading to a rare terminal Cu-alumanyl complex 8. The electronic structures of such complexes and the mechanism of the aluminylene-alumanyl transformation are investigated through density functional theory (DFT) calculations.

Are luminescent Ru2+ chelated complexes selective coordinative sensors for the detection of heavy cations ?

2021 ◽  
Author(s):  
Christophe Gourlaouen ◽  
Benjamin Schweitzer ◽  
Chantal Daniel
Keyword(s):  
Density Functional Theory ◽  
Transition Metals ◽  
Density Functional ◽  
Functional Theory ◽  
Group 12

The ability of [Ru(bpy)2(bpym)]2+ (bpy = 2,2’-biprydine; bpym = 2,2’-bipyrimidine) at probing specifically heavy cations has been investigated by means of density functional theory for transition metals, group 12 elements...

scholarly journals Theoretical design of a technetium-like alloy and its catalytic properties

2019 ◽  
Vol 10 (21) ◽  
pp. 5461-5469
Author(s):  
Wei Xie ◽  
Michihisa Koyama
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Catalytic Activity ◽  
Density Of States ◽  
Phase Stability ◽  
Density Functional ◽  
Catalytic Properties ◽  
Functional Theory ◽  
Theoretical Design ◽  
Structure Phase

Based on the concept of density of states (DOS) engineering, we theoretically designed a pseudo-Tc material (Mo–Ru alloy) and investigated its electronic structure, phase stability and catalytic activity by using density functional theory.

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