Six Low-Lying Isomers of C11H8 Are Unidentified in the Laboratory - a Theoretical Study

Spectroscopic Studies ◽

Intrinsic Reaction Coordinate ◽

Ionization Mass ◽

Functional Theory ◽

Cluster Methods ◽

Derivatives Of

The potential energy surface of C11H8 has been theoretically examined using density functional theory and coupled-cluster methods. The current investigation reveals that 2aH-cyclopenta[cd]indene (2), 7-ethynyl-1H-indene (6), 4-ethynyl-1H-indene (7), 6-ethynyl-1H-indene(8), 5-ethynyl-1H-indene (9), and 7bH-cyclopenta[cd]indene (10) remain elusive to date in the laboratory. The puckered low-lying isomer 2 lies at 11 kJ mol−1 below the experimentally known molecule, cyclobuta[de]naphthalene (3), at the fc-CCSD(T)/cc-pVTZ//fc-CCSD(T)/cc-pVDZ level of theory. 2 lies at 35 kJ mol−1 above the thermodynamically most stable and experimentally known isomer, 1H-cyclopenta[cd]indene (1), at the same level. It is identified that 1,2-H transfer from 1 yields 2H-cyclopenta[cd]indene (14) and subsequent 1,2-H shift from 14 yields 2. Appropriate transition states have been identified and intrinsic reaction coordinate calculations have been done at the B3LYP/6-311+G(d,p) level of theory. Recently, 1-ethynyl-1H-indene (11) has been detected using synchrotron based vacuum ultraviolet ionization mass spectrometry. 2-ethynyl-1H-indene (4) and 3-ethynyl-1H-indene (5) have been synthetically characterized in the past. While the derivatives of 7bH-cyclopenta[cd]indene (10) have been isolated elsewhere, the parent compound remains unidentified to date in the laboratory. Although C11H8 is a key elemental composition in reactive intermediates chemistry and most of its isomers are having a non-zero dipole moment, to the best of our knowledge, none of them have been characterized by rotational spectroscopy. Therefore, energetic and spectroscopic properties have been computed and the present investigation necessitates new synthetic studies on C11H8, in particular 2, 6-10, and also rotational spectroscopic studies on all low-lying isomers.

TDDFT STUDY OF NUCLEOBASE THIOANALOGUES AND OXO-DERIVATIVES EXCITED STATES

Journal of Theoretical and Computational Chemistry ◽

10.1142/s021963360900454x ◽

2009 ◽

Vol 08 (01) ◽

pp. 71-83 ◽

Cited By ~ 8

Author(s):

VJERAN GOMZI

Keyword(s):

Nucleic Acid ◽

Excited States ◽

Density Functional ◽

Triplet Excited State ◽

Energy Localization ◽

Nucleic Acid Bases ◽

Functional Theory ◽

Lower Excitation ◽

Derivatives Of

Thioanalogues of nucleic-acid bases have been shown to be the place of preferential charge or energy localization when incorporated in the system of respective regular bases. Most evidence of such behavior is based on experiments using γ-ray or other ionizing radiation. Here time dependent density functional theory (TDDFT) has been applied to investigate singlet and triplet excited state spectra of thioanalogues and some oxo-derivatives of nucleic-acid bases and compare the spectra to the calculated spectra of the regular bases as well as to the existing experimental data. It has been shown that thioanalogues have lower excitation singlet and triplet energies than are the respective energies in the regular bases. Energy localization on thioanalogues and their spectroscopic properties are related to the effect of sulfur substitution in such systems.

Infrared and Raman Spectroscopic Studies of Tris(trimethylsilyl)silane Derivatives of ((CH3)3Si)3Si-X [X = H, Cl, OH, CH3, OCH3, Si(CH3)3]: Vibrational Assignments by Hartree-Fock and Density-functional Theory Calculations

Journal of the Korean Physical Society ◽

10.3938/jkps.59.3192 ◽

2011 ◽

Vol 59 (5(1)) ◽

pp. 3192-3200 ◽

Cited By ~ 12

Author(s):

Bong Hyun Boo

Keyword(s):

Density Functional ◽

Density Functional Theory Calculations ◽

Spectroscopic Studies ◽

Functional Theory ◽

Vibrational Assignments ◽

Raman Spectroscopic ◽

Hartree Fock ◽

Derivatives Of

A computational study for the reaction mechanism of metal-free cyanomethylation of aryl alkynoates with acetonitrile

RSC Advances ◽

10.1039/d1ra01649k ◽

2021 ◽

Vol 11 (30) ◽

pp. 18246-18251

Author(s):

Selçuk Eşsiz

Keyword(s):

Reaction Mechanism ◽

Density Functional ◽

Computational Study ◽

Coupled Cluster ◽

Functional Theory ◽

Metal Free ◽

Coupled Cluster Methods ◽

High Level ◽

Cluster Methods

A computational study of metal-free cyanomethylation and cyclization of aryl alkynoates with acetonitrile is carried out employing density functional theory and high-level coupled-cluster methods, such as [CCSD(T)].

Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters

Scientific Reports ◽

10.1038/s41598-021-95551-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Christian Wiebeler ◽

Joachim Vollbrecht ◽

Adam Neuba ◽

Heinz-Siegfried Kitzerow ◽

Stefan Schumacher

Keyword(s):

Absorption Spectra ◽

Density Functional ◽

Energy Levels ◽

Absorption Bands ◽

Functional Theory ◽

Vertical Excitation ◽

Hartree Fock ◽

Tauc Plot ◽

Electrochemical Approach

AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands.

Time-Dependent Density Functional Theory Calculations of Photoabsorption Spectra in the Vacuum Ultraviolet Region

The Journal of Physical Chemistry A ◽

10.1021/jp003937v ◽

2001 ◽

Vol 105 (20) ◽

pp. 4953-4962 ◽

Cited By ~ 167

Author(s):

Nobuyuki N. Matsuzawa ◽

Akihiko Ishitani ◽

David A. Dixon ◽

Tsuyoshi Uda

Keyword(s):

Density Functional ◽

Vacuum Ultraviolet ◽

Density Functional Theory Calculations ◽

Time Dependent ◽

Ultraviolet Region ◽

Functional Theory ◽

Vacuum Ultraviolet Region ◽

Dependent Density

MOLECULAR STRUCTURE, QUANTUM CHEMICAL AND SPECTROSCOPIC PROPERTIES OF 2,6–DIBROMONAPHTHALENE BY DENSITY FUNCTIONAL THEORY CALCULATIONS

Journal of Molecular Structure ◽

10.1016/j.molstruc.2021.131834 ◽

2021 ◽

pp. 131834

Author(s):

Tevfik Raci SERTBAKAN ◽

Fatmanur ÖZÇELİK

Keyword(s):

Molecular Structure ◽

Quantum Chemical ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Functional Theory

COMPLEX DONORS IN NITROGEN-DOPED DIAMOND

International Journal of Nanoscience ◽

10.1142/s0219581x04002255 ◽

2004 ◽

Vol 03 (04n05) ◽

pp. 455-461

Author(s):

YING DAI ◽

ANYI LI ◽

YING ZHANG ◽

SHENGHAO HAN

Keyword(s):

Density Functional ◽

Shallow Donor ◽

Dangling Bond ◽

Single Vacancy ◽

Functional Theory ◽

Nitrogen Doped ◽

Ultrananocrystalline Diamond ◽

Cluster Methods ◽

Donor Character

Several Nitrogen (N)-hydrogen(H), N-dangling bond (DB) and N-single vacancy (V) complexes as the possible donor centers in diamond have been investigated using both supercell and cluster methods within the frame of density functional theory. We have found that the H—N—N—H complex exhibits shallower donor character than that of the N—H—N center discussed by Miyazaki et al.1 and it is one of the possible effective shallow donor centers in crystalline diamond. We conclude that the N—V related complex demonstrates a character of shallow donors and it should be one of the possible donor centers for the ultrananocrystalline diamond (UNCD) films, which are responsible for the n-type high conductivity of these films.

Spectroscopic and Electrochemical Investigations of New 5-oxo-2- Phenyloxazol-4(5H)-ylidene Based Triazine Derivatives

10.33790/crmc1100102 ◽

2019 ◽

Vol 1 (1) ◽

Keyword(s):

Density Functional ◽

Energy Gap ◽

Electronic Absorption Spectra ◽

Functional Theory ◽

Structural Framework ◽

Triazine Derivatives ◽

Homo And Lumo ◽

Cyclic Voltammetry Analysis ◽

Oxazolone Ring

The present study reports the two step synthesis of a novel oxazolone derivative, 4-((4,6-bis(4-((Z)-(5-oxo-2-phenyloxazol-4(5H)-ylidene) methyl)phenoxy)-1,3,5-triazin-2-yl) oxy) benzaldehyde (CBOZ (5)), containing two oxazolone ring substituted with central triazine nucleus in their structural framework. The structural and spectroscopic properties of synthesized CBOZ (5) were characterized by FTIR, 1HNMR, 13CNMR, and mass spectroscopic analysis. The UV-Vis absorption of CBOZ (5) showed a single absorption band at ~370 nm due to π-π* transition with the estimated energy gap of ~3.02 eV. Cyclic voltammetry analysis revealed that the synthesized CBOZ (5) obtained the HOMO and LUMO values of -5.87 eV and-2.85 eV, respectively. Density functional theory (DFT) studies were carried out to predict the electronic absorption spectra of CBOZ (5) and the obtained values were in excellent agreement with the experimental results.

Molecular bending as a vital step toward transforming planar PAHs to fullerenes and tubular structures

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039241 ◽

2020 ◽

Vol 644 ◽

pp. A146

Author(s):

Tao Chen ◽

Yang Wang

Keyword(s):

Density Functional ◽

Intermolecular Forces ◽

Molecular Structures ◽

Intrinsic Reaction Coordinate ◽

Functional Theory ◽

B3lyp Method ◽

Polycyclic Aromatic ◽

Chemical Studies ◽

Quantum Chemical Studies ◽

Hybrid Density Functional

Context. Polycyclic aromatic hydrocarbons (PAHs) and fullerenes are the largest molecules found in the interstellar medium (ISM). They are abundant and widespread in various astronomical environments. However, the detailed connection between these two species is unknown; in particular, no quantum chemical studies have been performed. Aims. In this work, we investigate a vital step in transforming planar PAHs to fullerenes, that is, the tubulation processes of PAHs. Methods. We used density functional theory for this study. The molecular structures and vibrational frequencies were calculated using the hybrid density functional B3LYP method. To better describe intermolecular forces, we considered Grimme’s dispersion correction in the calculations for this work. Intrinsic reaction coordinate calculations were also performed to confirm that the transition state structures are connected to their corresponding local potential energy surface minima. Results. As expected, we find that it is easier to bend a molecule as it gets longer, whereas it is harder to bend the molecule if it gets “wider” (i.e., with more rows of benzene rings). The change of multiplicity slightly alters the bending energies, while (a complete) dehydrogenation alleviates the bending barrier significantly and facilitates the formation of pentagons, which may act as an indispensable step in the formation of fullerenes in the ISM.