Tuning the Band-gap of Pt(II) Di-ynes and Poly-ynes by Incorporating Cl(CO)3Re(I) side-chain

2018 ◽  
Vol 1 (1) ◽  
pp. 45
Author(s):  
Idris Juma Al-Busaidi ◽  
Ashanul Haque ◽  
Muhammad S. Khan
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Computational Study ◽  
Side Chain ◽  
Highest Occupied Molecular Orbital ◽  
The Density Functional Theory ◽  
Device Applications ◽  
Group Variation ◽  
The Impact

Band-gap (Eg) of a material is an important criterion for application in opto-electronic (O-E) devices.1,2 Both low- and high Eg materials are useful and being synthesized by chemists via core structure modification, functional group variation and metal incorporation.3,4 We present herein computational study on the impact of incorporation of a Re(I) side-chain in 2,2’-bipyridine based Pt(II) di-ynes and poly-ynes. The density functional theory (DFT) calculation shows that the incorporation Cl(CO)3Re(I) as pendant functionality in 2,2’-bipyridine-based main-chain Pt(II) di- ynes and poly-ynes significantly reduce the Eg of the materials. Furthermore, to assess the role of positional isomerism, we compare the electronic structure and properties of 5,5’-and 6,6’- disubstituted 2,2’-bipyridine incorporated homo- and hetero-bimetallic diynes and poly-ynes . We find that the coordination of ReCO3 Cl moiety to Pt(II) di-yne introduces new Re(I)-localized highest occupied molecular orbital (HOMO) and the lowers the Eg by around 0.7 eV. Furthermore, our experimental results reveal that 5,5’-disubstituted 2,2’-bipyridine-based hetero-bimetallic di- ynes and polyynes are better materials for future O-E device applications.

Mechanistic insight into the selective trans-1,4-polymerization of butadiene by terpyridine–iron(II) complexes — A computational study

2009 ◽  
Vol 87 (10) ◽  
pp. 1392-1405 ◽  
Author(s):  
Sven Tobisch
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Dft Method ◽  
Chain Growth ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Insertion Mechanism ◽  
Trans Regulation ◽  
Insight Into

The density functional theory (DFT) method has been employed to unravel mechanistic intricacies of the 1,4-polymerization of 1,3-butadiene mediated by the [(η3-RC3H4)FeII(C15H11N3)(η2-C4H6)]+ terpyridine–iron(II) active catalyst species. The π-allyl-insertion mechanism is operative for chain growth, whilst the alternative σ-allyl-insertion mechanism has been explicitly demonstrated as being inoperable. This study elucidates the mechanism of cis–trans regulation and unveils the factors that govern the observed high trans-1,4 stereoselectivity, in particular, the discriminative role of allylic isomerization. An atactic trans-1,4-polydiene is expected from polymerization of a terminally monosubstituted butadiene, the experimental results of which have not been reported thus far.

scholarly journals Mononuclear Cr(III), Mn (II), and Fe(III) complexes derived from new ONO symmetrical flexible hydrazone: synthesis, spectral characterization, optical band gap and DFT computational study

2019 ◽  
Vol 8 (4) ◽  
pp. 743-753
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Optical Band Gap ◽  
Computational Study ◽  
Atomic Charge ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Stability ◽  
Global And Local

New mononuclear Mn (II), Cr (III) and Fe (III) complexes of flexible symmetrical 2-(2-(2-hydroxy-3-methoxybenzylidene) hydrazinyl)-2-oxo-N-(pyridine-2-yl) acetamid (H4MPA) were isolated and characterized. IR spectra proved that the hydrazone coordinates as ONO dibasic or monobasic in keto and enol forms. The density functional theory (DFT) based quantum chemical calculations were accomplished at B3LYP/6-level of theory. Muilikan atomic charge in a companion with global and local reactivities and various energitic values have been calculated at the selected atoms, and the reactive sites have been assigned on the surface of the molecules through molecular electrostatic potential (MEP) map. The stability of all compounds was examined by TGA and DrTGA and the associated kinetic parameters were determined. Also, the optical band gap values were evaluated and found to be comparable with those obtained by DFT suggesting the possibility of using the title compounds in solar cells.

A New Approach for Calculating the Band Gap of Semiconductors within the Density Functional Method

2015 ◽  
Vol 242 ◽  
pp. 434-439 ◽  
Author(s):  
Vasilii E. Gusakov
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Localized States ◽  
Experimental Accuracy ◽  
Functional Theory ◽  
New Approach ◽  
The Density Functional Theory

Within the framework of the density functional theory, the method was developed to calculate the band gap of semiconductors. We have evaluated the band gap for a number of monoatomic and diatomic semiconductors (Sn, Ge, Si, SiC, GaN, C, BN, AlN). The method gives the band gap of almost experimental accuracy. An important point is the fact that the developed method can be used to calculate both localized states (energy deep levels of defects in crystal), and electronic properties of nanostructures.

scholarly journals Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 26-37
Author(s):  
Karolina Zawadzińska ◽  
Karolina Kula
Keyword(s):  
Density Functional ◽  
Reaction Path ◽  
Computational Study ◽  
Cyano Group ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Reaction Channels ◽  
One Step ◽  
Step Mechanism

The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participation of β-phosphorylatednitroethene 2a and β-phosphorylated α-cyanonitroethene 2b, the more favored reaction path forms 4-nitro-substituted Δ2-isoxazolines 3a–b, while for a reaction with β-phosphorylated β-cyanonitroethene 2c, the more favored path forms 5-nitro-substituted Δ2-isoxazoline 4c. This is due to the presence of a cyano group in the alkene. The CDFT study correlates well with the analysis of the kinetic description of the considered reaction channels. Moreover, DFT calculations have proven the clearly polar nature of all analyzed [3+2] cycloaddition reactions according to the polar one-step mechanism.

scholarly journals Computational study on the mechanism of metal-free photochemical borylation of aryl halides

2021 ◽  
Author(s):  
Chenhao Tu ◽  
Nana Ma ◽  
Qingli Xu ◽  
Wenyue Guo ◽  
Lanxin Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Uv Light ◽  
Computational Study ◽  
Halogen Bond ◽  
Bond Cleavage ◽  
Aryl Halides ◽  
Homolytic Cleavage ◽  
Functional Theory ◽  
Aryl Radicals

C-radical borylation is an significant approach for the construction of carbon−boron bond. Photochemical borylation of aryl halides successfully applied this strategy. However, precise mechanisms, such as the generation of aryl radicals and the role of base additive(TMDAM) and water, remain controversy in these reactions. In this study, photochemical borylation of aryl halides has been researched by density functional theory (DFT) calculations. Indeed, the homolytic cleavage of the C−X bond under irradiation with UV-light is a key step for generation of aryl radicals. Nevertheless, the generation of aryl radicals may also undergo the process of single electron transfer and the heterolytic carbon-halogen bond cleavage sequence, and the latter is favorable during the reaction.

Modeling of Atomistic Processes in Semiconductors: from Defect Signatures to a Hierarchy of Annealing Mechanisms

2006 ◽  
Vol 978 ◽  
Author(s):  
Michel Bockstedte
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
The Self ◽  
Functional Theory ◽  
Dopant Activation ◽  
Defect Centers ◽  
The Density Functional Theory ◽  
Modeling And Experiments ◽  
Microscopic Origin

AbstractThe modeling of atomistic processes in semiconductors based on the density functional theory is outlined. The role of intrinsic defects in the self and dopant diffusion, as well as in the dopant activation is investigated for the case of silicon carbide. A hierarchy of annealing mechanisms for vacancies and interstitials is proposed. The identification of the microscopic origin of experimental defect centers by calculated defect signatures establishes a link between theoretical modeling and experiments.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

scholarly journals Synthesis, X-Ray Crystallography, Thermal Analysis, and DFT Studies of Ni(II) Complex with 1-Vinylimidazole Ligand

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Fatih Şen ◽  
Ramazan Şahin ◽  
Muharrem Dinçer ◽  
Ömer Andaç ◽  
Murat Taş
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Basis Sets ◽  
Mulliken Charge ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Dft Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Density Functional Theory

The paper presents a combined experimental and computational study of hexa(1-vinylimidazole)Ni(II) perchlorate complex. The complex was prepared in the laboratory and crystallized in the monoclinic space group P21/n with a=8.442(5), b=13.686(8), c=16.041(9) Å, α=γ=90, β=96.638(5), and Z=1. The complex has been characterized structurally (by single-crystal X-Ray diffraction) and its molecular structure in the ground state has been calculated using the density functional theory (DFT) methods with 6-31G(d) and LanL2DZ basis sets. Thermal behaviour and stability of the complex were studied by TGA/DTA analyses. Besides, the nonlinear optical effects (NLO), molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and the Mulliken charge distribution were investigated theoretically.

Graphene-Based Sensors for Monitoring Strain

2013 ◽  
Vol 3 (1) ◽  
pp. 74-83
Author(s):  
M. Mirnezhad ◽  
R. Ansari ◽  
H. Rouhi ◽  
M. Faghihnasiri
Keyword(s):  
Fermi Level ◽  
Band Gap ◽  
Strain Distribution ◽  
Density Functional ◽  
Tight Binding ◽  
Density Functional Theory Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Gap Opening

The application of graphene as a nanosensor in measuring strain through its band structure around the Fermi level is investigated in this paper. The mechanical properties of graphene as well as its electronic structure are determined by using the density functional theory calculations within the framework of generalized gradient approximation. In the case of electronic properties, the simulations are applied for symmetrical and asymmetrical strain distributions in elastic range; also the tight-binding approach is implemented to verify the results. It is indicated that the energy band gap does not change with the symmetrical strain distribution but depend on the asymmetric strain distribution, increasing strain leads to band gap opening around the Fermi level.

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