scholarly journals Diboron- and Diaza-Doped Anthracenes and Phenanthrenes: Their Electronic Structures for Being Singlet Fission Chromophores

2020 ◽  
Author(s):  
Ekadashi Pradhan ◽  
Tao Zeng
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Orbital Energy ◽  
Frontier Orbital ◽  
Singlet Fission ◽  
Functional Theory ◽  
Alternant Hydrocarbon ◽  
Mirror Relation ◽  
Frontier Orbital Energy

<p>We used quantum chemistry methods at the levels of mixed-reference spin-flipping time-dependent density functional theory and multireference perturbation theory to study diboron- and diaza-doped anthracenes and phenanthrenes. This class of structures recently surged as potential singlet fission chromophores. We studied electronic structures of their excited states and clarify the reasons why they satisfy or fail to satisfy the energy criteria for singlet fission chromophores. Many studied structures have their S<sub>1</sub> states not dominated by HOMO->LUMO excitation, so that they cannot be described using the conventional two sites model. This is attributed to frontier orbital energy shifts induced by the doping and different charge transfer energies in different one-electron singlet excitations, or in other words different polarizations of hole and/or particle orbitals in their S<sub>1</sub> and T<sub>1</sub> states. There is a mirror relation between the orbital energy shifts induced by diboron- and diaza-dopings, which, together with alternant hydrocarbon pairings of occupied and unoccupied orbitals, leads to more mirror relations between the excited states' electronic structures of the two types of doped structures. </p>

scholarly journals Diboron- and Diaza-Doped Anthracenes and Phenanthrenes: Their Electronic Structures for Being Singlet Fission Chromophores

2020 ◽  
Author(s):  
Ekadashi Pradhan ◽  
Tao Zeng
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Orbital Energy ◽  
Frontier Orbital ◽  
Singlet Fission ◽  
Functional Theory ◽  
Alternant Hydrocarbon ◽  
Mirror Relation ◽  
Frontier Orbital Energy

<p>We used quantum chemistry methods at the levels of mixed-reference spin-flipping time-dependent density functional theory and multireference perturbation theory to study diboron- and diaza-doped anthracenes and phenanthrenes. This class of structures recently surged as potential singlet fission chromophores. We studied electronic structures of their excited states and clarify the reasons why they satisfy or fail to satisfy the energy criteria for singlet fission chromophores. Many studied structures have their S<sub>1</sub> states not dominated by HOMO->LUMO excitation, so that they cannot be described using the conventional two sites model. This is attributed to frontier orbital energy shifts induced by the doping and different charge transfer energies in different one-electron singlet excitations, or in other words different polarizations of hole and/or particle orbitals in their S<sub>1</sub> and T<sub>1</sub> states. There is a mirror relation between the orbital energy shifts induced by diboron- and diaza-dopings, which, together with alternant hydrocarbon pairings of occupied and unoccupied orbitals, leads to more mirror relations between the excited states' electronic structures of the two types of doped structures. </p>

Spectroscopic trends in a series of Re(I) α-diimine complexes as a function of the antenna/photoisomerizable ligands: a TD-DFT and MS-CASPT2 study

2014 ◽  
Vol 92 (10) ◽  
pp. 979-986 ◽  
Author(s):  
Megumi Kayanuma ◽  
Chantal Daniel ◽  
Etienne Gindensperger
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Time Dependent ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ligand Charge Transfer ◽  
Td Dft ◽  
Energy Domain ◽  
Diimine Complexes

The absorption spectra of 11 rhenium(I) complexes with photoisomerizable stilbene-like ligands have been investigated by means of density functional theory (DFT). The electronic structures of the ground and excited states were determined for [Re(CO)3(N,N)(L)]+ (N,N = bpy (2,2′-bipyridine), phen (1,10-phenanthroline), Me4phen (3,4,7,8-tetramethyl-1,10-phenanthroline), ph2phen (4,7-diphenyl-1,10-phenanthroline), or Clphen (5-chloro-1,10-phenanthroline); L = bpe (1,2-bis(4-pyrydil)ethylene), stpy (4-styrylpyridine), or CNstpy (4-(4-cyano)styrylpyridine)) at the time–dependent (TD) DFT/CAM-B3LYP level of theory in vacuum and acetonitrile to highlight the effects of both antenna N,N and isomerizable L ligands. The TD-DFT spectra of two representative complexes, namely [Re(CO)3(bpy)(stpy)]+ and [Re(CO)3(phen)(bpe)]+, have been compared with MS-CASPT2 spectra. The TD-DFT spectra obtained in vacuum and acetonitrile agree rather well both with the ab initio and experimental spectra. The absorption spectroscopy of this series of molecules is characterized by the presence of three low-lying metal to ligand charge transfer (MLCT) states absorbing in the visible energy domain. The nature of the isomerizable ligands (bpe, stpy, or CNstpy) and the type of antenna ligands (bpy, phen, and substituted phen) control the degree of mixing between the MLCT and intraligand excited states, their relative energies, as well as their intensities.

Organometallic pyrene-containing porphyrins: Synthesis, characterization, and non-covalent interactions with C60 fullerenes

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1098-1113 ◽  
Author(s):  
Yang Li ◽  
Hannah M. Rhoda ◽  
Anthony M. Wertish ◽  
Victor N. Nemykin
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
C60 Fullerenes

A reaction between 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin and 1-bromopyrene resulted in the formation of 5,10,15,20-tetra[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (1), while cross-condensation between 4-(4-(pyrenyl-1)butoxy)benzaldehyde, ferrocenecaboxaldehyde, and pyrrole resulted in the formation of 5-ferrocenyl-10,15,20-tri[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (2), 5,10-diferrocenyl-15,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (3), and 5,15-diferrocenyl-10,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (4). All pyrene-containing porphyrins were characterized by 1H NMR, UV-vis, MCD, and high-resolution ESI methods, while their electronic structures and the nature of the excited states were elucidated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The molecular structure of 1 and its fluorescence quenching upon the addition of C[Formula: see text] fullerene was also investigated using X-ray crystallography and steady-state fluorescence approaches.

C60 as Electron Acceptor and Donor: A Comparative DFT Study of Li@C60 and F@C60

2018 ◽  
Vol 71 (12) ◽  
pp. 953 ◽  
Author(s):  
Ambrish Kumar Srivastava ◽  
Sarvesh Kumar Pandey ◽  
Anoop Kumar Pandey ◽  
Neeraj Misra
Keyword(s):  
Charge Transfer ◽  
Electron Acceptor ◽  
Density Functional ◽  
Energy Gap ◽  
Orbital Energy ◽  
Prototype System ◽  
Theory Approach ◽  
Frontier Orbital ◽  
Functional Theory ◽  
Fundamental Properties

Fullerene (C60) is a stable prototype system for a special class of nanomaterials. In this work, the smallest alkali metal (Li) and halogen (F) atoms were encapsulated in the C60 cage, and comparative quantum chemical calculations (QCCs) were performed on their various properties using a density functional theory approach. It was noted that the off-centre distance of Li is higher than that of F. The QCCs of the charge transfer to and from C60 were also analysed. Although charge transfer to and from the C60 cage takes place in both cases, Li@C60 becomes more polar than F@C60, suggesting a better electron-accepting nature of C60 than electron-donating behaviour. This fact is consistent with the natural bond orbital (NBO) charge on the trapped atoms and the dipole moment as well as the binding energy values of the encapsulated C60. Although the encapsulation of both atoms reduces the frontier orbital energy gap, the frontier orbital gap of Li@C60 is smaller than that of F@C60. More interestingly, the depression in the polarizability of Li@C60 is significantly large relative to that of F@C60. These findings also support the tendency of C60 to act as electron acceptor. This study provides some insights into the fundamental properties of C60 and should be helpful in designing new endofullerene complexes for a variety of applications.

High ozone chemisorption by using metal–cluster complexes: a DFT study on the nickel-decorated B12P12 nanoclusters

2017 ◽  
Vol 95 (8) ◽  
pp. 845-850 ◽  
Author(s):  
Ali Shokuhi Rad
Keyword(s):  
Adsorption Energy ◽  
Electronic Structures ◽  
Density Functional ◽  
Metal Cluster ◽  
Bond Distance ◽  
Frontier Orbital ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Charge Analysis ◽  
Orbital Analysis

In the present study, by using first-principle study within the density functional theory (DFT), we investigated the ozone (O3) chemisorption on the surface of pristine and nickel-decorated B12P12 nanoclusters. The important emphasis of this study is to follow changes in the electronic structures of the aforementioned nanoclusters upon adsorption of the O3 molecule. Although we found strong chemisorption of O3 on a pristine nanocluster (–282.7 kJ/mol), significant increases in adsorption were found by modifying the nanocluster’s surface. Firstly, we found there are three possible sites on the surface of the nanocluster for nickel (Ni) decoration. For each Ni-decorated nanocluster, we searched its potential for adsorption of O3 by using quantum chemical calculations. Depending on the location of decorated Ni, we found considerable increased values of O3 adsorption energy (–340.8, –376.8, and –382.4 kJ/mol). We carried out calculations by taking into account the values of adsorption energy, bond distance, dipole moment study, charge analysis, frontier orbital analysis, and density of states of all relaxed systems.

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>

scholarly journals Study of Anharmonicity in Zirconium Hydrides Using Inelastic Neutron Scattering and Ab-Initio Computer Modeling

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 29
Author(s):  
Jiayong Zhang ◽  
Yongqiang Cheng ◽  
Alexander I. Kolesnikov ◽  
Jerry Bernholc ◽  
Wenchang Lu ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Excited States ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Vibrational States ◽  
Functional Theory ◽  
Hydrogen Deuterium ◽  
Zirconium Hydrides

The anharmonic phonon behavior in zirconium hydrides and deuterides, including ϵ-ZrH2, γ-ZrH, and γ-ZrD, has been investigated from aspects of inelastic neutron scattering (INS) and lattice dynamics calculations within the framework of density functional theory (DFT). The harmonic model failed to reproduce the spectral features observed in the experimental data, indicating the existence of anharmonicity in those materials and the necessity of further explanations. Here, we present a detailed study on the anharmonicity in zirconium hydrides/deuterides by exploring the 2D potential energy surface of hydrogen/deuterium atoms and solving the corresponding 2D single-particle Schrödinger equation to obtain the eigenfrequencies, which are then convoluted with the instrument resolution. The convoluted INS spectra qualitatively describe the anharmonic peaks in the experimental INS spectra and demonstrate that the anharmonicity originates from the deviations of hydrogen potentials from quadratic behavior in certain directions; the effects are apparent for the higher-order excited vibrational states, but small for the ground and first excited states.

Sign in / Sign up

Export Citation Format

Share Document