Computational Spectroscopic Characterization of a Bistable Binuclear Complex [(CO)2(benzoate)FeII/III(terephthalate)CoIII/II(benzoate)(CO)2]+

2018 ◽  
Vol 71 (5) ◽  
pp. 348 ◽  
Author(s):  
Hossein Shirani ◽  
Hassan Sabzyan
Keyword(s):  
Binuclear Complex ◽  
Density Functional ◽  
Complex Analysis ◽  
Dipole Moments ◽  
Spectroscopic Characterization ◽  
Optical Rotatory Dispersion ◽  
Global Changes ◽  
Electric Response ◽  
Late Transition ◽  
Cis And Trans

Electric dipole moments, polarizabilities, and IR, Raman, optical rotatory dispersion, and electronic and vibrational circular dichroism spectra of the four cis–trans isomers of the proposed [(CO)2(benzoate)FeII/III(terephthalate)CoIII/II(benzoate)(CO)2]+ binuclear complex, having bistablity due to intramolecular charge transfer (IMCT), is investigated using the time-dependent density functional theory ((TD)DFT) B3LYP/6–31G(d,p)[LanL2DZ] method. Results show that the two FeII–CoIII and FeIII–CoII IMCT states of this binuclear complex have distinctly different spectroscopic, optical, and electric response properties, and are sensitive to the cis–trans arrangement of the ligands around the two metallic centres. Furthermore, intrinsic reaction coordinates inter-connecting the two IMCT states are identified using the Duschinsky matrix method. Only one or two of the normal coordinates remain almost (above 80 %) intact during the IMCT reaction which denotes global changes in the bonding strengths and potential energy hypersurface of this bistable binuclear complex. Analysis of the calculated spin densities characterizes the IMCT transition state structures of the trans–trans, cis–cis, and trans–cis isomers as early, early, and late transition states, respectively.

Gas-phase spectroscopic characterization of neutral and ionic polycyclic aromatic phosphorus heterocycles (PAPHs)

2020 ◽  
Vol 500 (2) ◽  
pp. 2564-2576
Author(s):  
Ricardo R Oliveira ◽  
Germán Molpeceres ◽  
Felipe Fantuzzi ◽  
Heidy M Quitián-Lara ◽  
Heloisa M Boechat-Roberty ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Density Functional ◽  
Dipole Moments ◽  
Closed Shell ◽  
Spectroscopic Characterization ◽  
Infrared Emission ◽  
Proton Affinities ◽  
Anionic Species ◽  
Polycyclic Aromatic ◽  
Phosphorus Heterocycles

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) constitute an essential family of compounds in interstellar (ISM) and circumstellar (CSM) media. Recently, formation routes for the corresponding polycyclic aromatic phosphorus heterocycles (PAPHs) in astrophysical environments have been proposed. In order to contribute to a better understanding of the phosphorus chemistry in the ISM, infrared (IR) spectra and selected properties of PAPHs were computed at the density functional theory level for neutral, cationic, and anionic species. Our results reveal that several protonated PAPHs do not have planar backbones, and all species have permanent dipole moments between 2D and 4D. Closed-shell PAPHs have similar ionization potentials compared to the parent PAHs, below the Lyman threshold limit. In addition, all PAPHs show positive electron affinities higher than those of PAHs. Protonation preferably occurs on the heteroatom but with lower proton affinities than those of the corresponding nitrogen analogues (polycyclic aromatic nitrogen heterocycles). In general, neutral species have similar IR spectra profile with the most intense bands around 800 cm−1 (12.5 μm) related to C−H wagging. Charge and protonation affect the IR spectra mainly by decreasing the intensities of these modes and increasing the ones between 1000 (10.0 μm) and 1800 cm−1 (5.6 μm). The P−H stretching appears in a different spectral region, between 2300 (4.3 μm) and 2700 cm−1 (3.7 μm). Our results are discussed in the context of distinct sources where PAHs and phosphorus are detected. PAPHs, in particular the coronene derivatives, can contribute to the unidentified infrared emission band at 6.2 μm.

Phosphoramides bearing isoxazole derivative: spectroscopic and structural characterization, study of hydrogen-bonding interactions and two lanthanide complexes (LnIII= Ce and Eu)

2015 ◽  
Vol 71 (2) ◽  
pp. 176-185 ◽  
Author(s):  
Khodayar Gholivand ◽  
Foroogh Molaei ◽  
Mahdieh Hosseini
Keyword(s):  
Lanthanide Complexes ◽  
Density Functional ◽  
Spectroscopic Characterization ◽  
Crystalline Lattice ◽  
Ligand Interaction ◽  
Functional Theory ◽  
X Ray Crystallography ◽  
Isoxazole Derivative ◽  
Characterization Study

In this study, the synthesis and spectroscopic characterization of new phosphoramides based on 3-amino-5-methylisoxazole with the formulaR2P(O)[NH–C4H4NO],R= C6H5O (1), C6H5(2),RP(O)[NH—C4H4NO]2,R= C6H5O (3), CH3—C6H4O (4), C6H5NH (5), (C6H5)ClP(O)[NH–C4H4NO] (6) and two lanthanide complexes [Ln(2)2(NO3)3(EtOH)]·EtOH, LnIII= Ce (7) and Eu (8), have been reported. The structural study of (3) shows the presence of two conformers (crystallographically independent molecules) in the crystalline lattice, caused by different orientations of the phenyl and isoxazole rings. For (3), the intermolecular interactions have been studied by Hirshfeld surface analysis and fingerprint plots. Furthermore, the electronic and energy aspects of hydrogen bonds between molecules of (3) have been explored by density functional theory (DFT) calculations. X-ray crystallography of complexes (7) and (8) reveals that two phosphoramide ligands take part in coordination to the metal, one as monodentate from Ophosphoryl, and the other one as chelate through Ophosphoryland Nring. The complexes are also composed of two conformers in the solid-state structure. Quantum theory of atoms in molecules (QTAIM) analysis discloses the electrostatic nature of the Ln–ligand interaction.

scholarly journals Crystal structure and spectroscopic characterization of a cobalt(II) tetraazamacrocycle: completing a series of first-row transition-metal complexes

2017 ◽  
Vol 73 (8) ◽  
pp. 620-624 ◽  
Author(s):  
Katherine M. Van Heuvelen ◽  
Isabell Lee ◽  
Katherine Arriola ◽  
Rilke Griffin ◽  
Christopher Ye ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Spin State ◽  
Density Functional ◽  
Cobalt Complex ◽  
Chloride Ion ◽  
Spectroscopic Characterization ◽  
Spectroscopic Studies ◽  
Chloride Dihydrate ◽  
Pyramidal Geometry ◽  
A Minor

The tetraazamacrocyclic ligand 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMC) has been used to bind a variety of first-row transition metals but to date the crystal structure of the cobalt(II) complex has been missing from this series. The missing cobalt complex chlorido(1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane-κ4 N)cobalt(II) chloride dihydrate, [CoCl(C14H32N4)]Cl·2H2O or [CoIICl(TMC)]Cl·2H2O, crystallizes as a purple crystal. This species adopts a distorted square-pyramidal geometry in which the TMC ligand assumes the trans-I configuration and the chloride ion binds in the syn-methyl pocket of the ligand. The CoII ion adopts an S = 3 \over 2 spin state, as measured by the Evans NMR method, and UV–visible spectroscopic studies indicate that the title hydrated salt is stable in solution. Density functional theory (DFT) studies reveal that the geometric parameters of [CoIICl(TMC)]Cl·2H2O are sensitive to the cobalt spin state and correctly predict a change in spin state upon a minor perturbation to the ligand environment.

scholarly journals Phosphorene–Fullerene Nanostructures: A First-Principles Study

2021 ◽  
Author(s):  
Diego Cortes-Arriagada ◽  
Daniela E. Ortega
Keyword(s):  
Active Sites ◽  
Short Range ◽  
Density Functional ◽  
Dipole Moments ◽  
Molecular Size ◽  
Bandgap Engineering ◽  
Donor Acceptor ◽  
The Stability ◽  
Strong Repulsion ◽  
Intermolecular Distances

Hybrid materials formed by carbon fullerenes and layered materials have emerged due to their advantages for several technological applications, and phosphorene arises as a promising two-dimensional semiconductor for C60 adsorption. However, the properties of phosphorenefullerene hybrids remain mainly unexplored. In this work, we employed density functional theory to obtain structures, adsorption energies, electronic/optical properties, binding (AIM, NBO), and energy decomposition analyses (ALMO-EDA) of nanostructures formed by phosphorene and fullerenes (C24 to C70). We find fullerenes form covalent and non-covalent complexes with phosphorene depending on the molecular size, showing remarkable stability even in solution. Two classes of covalent complexes arise by cycloaddition-like reactions: the first class, where short-range effects (charge-transfer and polarization) determines the stability; and the second one, where short-range effects decay to avoid steric repulsion, and balanced longrange forces (electrostatics and dispersion) favors the stability. Otherwise, high-size fullerenes (C50 to C70) only form non-covalent complexes due to strong repulsion at shorter intermolecular distances and lack of dissociation barriers. In terms of electronic properties, fullerenes act as mild p-dopants for phosphorene, increasing its polar character and ability to acquire induced dipole moments (polarizability). Also, small energy-bandgap fullerenes (<0.8 eV) largely increase the phosphorene metallic character. We also note fullerenes retain their donor/acceptor properties upon adsorption, acting as active sites for orbital-controlled interactions and maximizing the phosphorene light absorbance at the UV-Vis region. Finally, we strongly believe our study will inspire future experimental/theoretical studies focused on phosphorene-fullerene uses for storage, anode materials, sensing, phosphorene bandgap engineering, and optoelectronics.<br>

Density functional theory study on the structural, reactivity, and electronic properties of all mono-, di-, tri-, tetra-, and penta-fluoroanilines as monomers for conducting polymers

2012 ◽  
Vol 90 (10) ◽  
pp. 902-914 ◽  
Author(s):  
Hossein Shirani Il Beigi
Keyword(s):  
Density Functional Theory ◽  
Conducting Polymers ◽  
Structural Properties ◽  
Density Functional ◽  
Dipole Moments ◽  
Radical Cations ◽  
The Other ◽  
Functional Theory ◽  
Density Distributions ◽  
Electric Polarizabilities

Electrical and structural properties of mono-, di-, tri-, tetra-, and penta-fluoroanilines as candidate monomers for new conducting polymers have been investigated using hybrid density functional theory (B3LYP/6–311+G**) based methods. The effects of the number and position of the fluorine atoms on the electrical and structural properties of fluoroanilines and their radical cations have also been investigated. The values of the vibrational frequencies, charge and spin-density distributions, ionization potentials, dipole moments, electric polarizabilities, HOMO-LUMO gaps, and the NICS values of these compounds have been calculated and analyzed as well. The results showed that the double bonds in 2-fluoroaniline and 2,5-difluoroaniline are more delocalized compared with other fluoroanilines; therefore, these molecules have the most aptitude for the electropolymerization reactions. The frequency analysis showed that the electrochemical stability of 2-fluoroaniline is greater than the other fluoroanilines. Also, this molecule possesses the largest NICS value compared to the other fluoroanilines. Consequently, 2-fluoroaniline has the largest ring current and the highest conductivity among all other monomers. Based on the results obtained, 2-fluoroaniline and 2,5-difluoroaniline are the best candidate monomers among all fluoroanilines for the synthesis of corresponding conducting polymers.

Designing of Inorganic Al12N12 Nanocluster with Fe, Co, Ni, Cu and Zn Metals for Efficient Hydrogen Storage Materials

2021 ◽  
Vol 20 (04) ◽  
pp. 359-375
Author(s):  
Muhammad Yasir Mehboob ◽  
Fakhar Hussain ◽  
Riaz Hussain ◽  
Shaukat Ali ◽  
Zobia Irshad ◽  
...  
Keyword(s):  
Transition Metals ◽  
Hydrogen Storage ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Chemical Hardness ◽  
Hydrogen Storage Materials ◽  
Late Transition Metals ◽  
Storage Materials ◽  
Late Transition ◽  
Cu And Zn

Hydrogen is considered as one of the attractive environmentally friendly materials with zero carbon emission. Hydrogen storage is still challenging for its use in various energy applications. That’s why hydrogen gained more and more attention to become a major fuel of today’s energy consumption. Therefore, nowadays, hydrogen storage materials are under extensive research. Herein, efforts are being devoted to design efficient systems which could be used for future hydrogen storage purposes. To this end, we have employed density functional theory (DFT) to optimize the geometries of the designed inorganic Al[Formula: see text]N[Formula: see text] nanoclusters with transition metals (Fe, Co, Ni, Cu and Zn). Various positions of metal encapsulated Al[Formula: see text]N[Formula: see text] are examined for efficient hydrogen adsorption. After adsorption of H2 on late transition metals encapsulated Al[Formula: see text]N[Formula: see text] nanocluster, different geometric parameters like frontier molecular orbitals, adsorption energies and nature bonding orbitals have been performed for exploring the potential of metal encapsulated for hydrogen adsorption. Moreover, molecular electrostatic potential (MEP) analysis was also performed in order to explore the different charge separation upon H2 adsorption on metals encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters. Also, global indices of reactivity like ionization potential, electron affinity, electrophilic index, chemical softness and chemical hardness were also examined by using DFT. The adsorption energy results suggested encapsulation of late transition metals in Al[Formula: see text]N[Formula: see text] nanocage efficiently enhancing the adsorption capability of Al[Formula: see text]N[Formula: see text] for hydrogen adsorption. Results of all analysis suggested that our designed systems are efficient candidates for hydrogen adsorption. Thus, we recommended a novel kind of systems for hydrogen storage materials.

scholarly journals Metastable One-Electron Excited States of Charged Fullerenes

2019 ◽  
Vol 2019 ◽  
pp. 1-4
Author(s):  
Rafael V. Arutyunyan ◽  
Alexander D. Vasiliev ◽  
Yuri N. Obukhov ◽  
Alexander V. Osadchy
Keyword(s):  
Density Functional ◽  
Dipole Moments ◽  
Three Dimensional ◽  
Density Functional Theory Method ◽  
Transition Dipole ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Transition Dipole Moments ◽  
Quantum Transitions ◽  
Wavelength Radiation

We study the spontaneous emission processes for the quantum transitions between electron states of a charged C60 fullerene. Lifetimes for the transitions between the volume-localized electron levels and the surface-localized electron levels are evaluated and compared with the transitions between two surface-localized electron levels. We find the lifetimes by computing the transition dipole moments on the basis of the numeric calculations of the three-dimensional electron wave functions of a charged fullerene by making use of the density functional theory method implemented in the QuantumEspresso package. We show that the lifetime of a volume-localized level is of order of 1 μs for a transition energy of about 5 eV. This suggests to consider the possibility of using charged fullerenes for generating short-wavelength radiation, including coherent radiation in this range.

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