The ortho-benzyne cation is not planar

2018 ◽  
Vol 20 (6) ◽  
pp. 3988-3996 ◽  
Author(s):  
D. Kaiser ◽  
E. Reusch ◽  
P. Hemberger ◽  
A. Bodi ◽  
E. Welz ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
High Level ◽  
Quantum Chemical Computations

Mass-selected threshold photoelectron spectroscopy with synchrotron radiation and high-level quantum chemical computations revealed that the ground state of the ortho-benzyne cation exhibits a twisted geometry and that the ionisation energies have to be revised.

Excitons in poly(para phenylene vinylene): a quantum-chemical perspective based on high-level ab initio calculations

2016 ◽  
Vol 18 (4) ◽  
pp. 2548-2563 ◽  
Author(s):  
Stefanie A. Mewes ◽  
Jan-Michael Mewes ◽  
Andreas Dreuw ◽  
Felix Plasser
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Phenylene Vinylene ◽  
High Level ◽  
Quantum Chemical Computations

Exciton analyses of high-level quantum-chemical computations for poly(paraphenylene vinylene) reveal the nature of the excitonic bands in PPV oligomers.

scholarly journals Tetrel Bonding in CB11H11 Carbonium Ylide

2021 ◽  
Author(s):  
Maxime Ferrer ◽  
Ibon Alkorta ◽  
José Elguero ◽  
Josep M. Oliva-Enrich
Keyword(s):  
Lewis Acid ◽  
Quantum Chemical ◽  
Molecular Electrostatic Potential ◽  
Weak Interactions ◽  
Topological Analysis ◽  
Closed Shell ◽  
Lewis Bases ◽  
High Level ◽  
Quantum Chemical Computations ◽  
Vacant Orbital

High-level quantum-chemical computations (G4MP2) are carried out in the study of complexes featuring tetrel bonding between the carbon atom in the carbenoid CB11H11 - obtained by hydride removal in the C-H bond of the known closo-monocarbadodecaborate anion CB11H12() and acting as Lewis acid (LA) - and Lewis bases (LB) of different type; the electron donor groups in the tetrel bond feature carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulphur and chlorine atomic centers in neutral molecules as well as anions H(-), OH(-) and F(-). The empty radial 2pr vacant orbital on the carbon center in CB11H11 , which corresponds to the LUMO, acts as a Lewis acid or electron attractor, as shown by the molecular electrostatic potential (MEP) and electron localization funcion (ELF). The thermochemistry and topological analysis of the complexes {CB11H11:LB} are comprehensively analyzed, and classified according to sharing or closed-shell interactions. ELF analysis shows that the tetrel C···X bond ranges from very polarised bonds, as in H11B11C:F() to very weak interactions as in H11B11C···FH and H11B11C···O=C=O.

scholarly journals A Computational Journey across Nitroxide Radicals: From Structure to Spectroscopic Properties and Beyond

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7404
Author(s):  
Vincenzo Barone ◽  
Marco Fusè ◽  
Sandra Mónica Vieira Pinto ◽  
Nicola Tasinato
Keyword(s):  
Ground State ◽  
Quantum Chemical ◽  
Spectroscopic Properties ◽  
Open Shell ◽  
Spin Labels ◽  
Nitroxide Radicals ◽  
Large Panel ◽  
Hybrid Functionals ◽  
Quantum Chemical Computations ◽  
Electronic Ground

Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest.

scholarly journals Design of carborane molecular architectures with electronic structure computations: From endohedral and polyradical systems to multidimensional networks

2009 ◽  
Vol 81 (4) ◽  
pp. 719-729 ◽  
Author(s):  
Josep M. Oliva ◽  
Douglas J. Klein ◽  
Paul von Ragué Schleyer ◽  
Luis Serrano-Andrés
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical ◽  
Triplet States ◽  
Triplet Energy ◽  
Self Assembling ◽  
Energy Gaps ◽  
Molecular Architectures ◽  
High Level ◽  
Quantum Chemical Computations ◽  
Structure Properties

The 12 cage-anchoring points of the very stable icosahedral ortho-, meta-, and para-carborane allow the design of multidimensional architectures provided new self-assembling routes are devised. We provide bases for constructing carborane molecular architectures through high-level quantum chemical computations. We consider ejection mechanisms for the inner atom/ion in endohedral carborane complexes, singlet-triplet energy gaps in carborane biradicals, as well as geometry reorganization in carborane neutral and dianionic triplet states. These features, explored in monomers, are starting points for the design of molecular architectures based on electronic structure properties of carborane assemblies.

scholarly journals Double and Triple Ionisation of Isocyanic Acid

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. H. D. Eland ◽  
R. J. Squibb ◽  
A. J. Sterling ◽  
M. Wallner ◽  
A. Hult Roos ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Ground State ◽  
Photoelectron Spectrum ◽  
Theoretical Calculations ◽  
Isocyanic Acid ◽  
The Core ◽  
Coulomb Model ◽  
High Level ◽  
Double Ionisation ◽  
Reactive Molecule

AbstractDouble and triple ionisation spectra of the reactive molecule isocyanic acid (HNCO) have been measured using multi-electron and ion coincidence techniques combined with synchrotron radiation and compared with high-level theoretical calculations. Vertical double ionisation at an energy of 32.8 ± 0.3 eV forms the 3A” ground state in which the HNCO2+ ion is long lived. The vertical triple ionisation energy is determined as 65 ± 1 eV. The core-valence double ionisation spectra resemble the valence photoelectron spectrum in form, and their main features can be understood on the basis of a simple and rather widely applicable Coulomb model based on the characteristics of the molecular orbitals from which electrons are removed. Characteristics of the most important dissociation channels are examined and discussed.

scholarly journals Negative ion photoelectron spectroscopy confirms the prediction that D3h carbon trioxide (CO3) has a singlet ground state

2016 ◽  
Vol 7 (2) ◽  
pp. 1142-1150 ◽  
Author(s):  
David A. Hrovat ◽  
Gao-Lei Hou ◽  
Bo Chen ◽  
Xue-Bin Wang ◽  
Weston Thatcher Borden
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Radical Anion ◽  
Negative Ion ◽  
Singlet Ground State

The CO3 radical anion (CO3˙−) has been formed by electrospraying carbonate dianion (CO32−) into the gas phase.

scholarly journals Quantification of Carbonic Contamination of Fused Silica Surfaces at Different Stages of Classical Optics Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1620
Author(s):  
Robert Köhler ◽  
Domenico Hellrung ◽  
Daniel Tasche ◽  
Christoph Gerhard
Keyword(s):  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Decisive Role ◽  
Fused Silica ◽  
Process Step ◽  
Carbon Contamination ◽  
Silica Surfaces ◽  
Carbon Impurities ◽  
High Level ◽  
Glass Surfaces

The chemical composition of ground and polished fused silica glass surfaces plays a decisive role in different applications of optics. In particular, a high level of carbon impurities is often undesirable for further processing and especially for gluing or cementing where adhesion failure may be attributed to carbonic surface-adherent contaminants. In this study, the surface carbon content at different stages of classical optics manufacturing was thus investigated. Two different standard processes—grinding and lapping with two final polishing processes using both polyurethane and pitch pads—were considered. After each process step, the chemical composition and roughness of the surface were analysed using X-ray photoelectron spectroscopy and atomic force microscopy. An obvious correlation between surface roughness and effective surface area, respectively, and the proportion of carbon contamination was observed. The lowest carbon contamination was found in case of lapped and pitch polished surfaces.

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