scholarly journals Direct Detection and Characterization of Chloride in the Active Site of the Low-pH Form of Sulfite Oxidase Using Electron Spin Echo Envelope Modulation Spectroscopy, Isotopic Labeling, and Density Functional Theory Calculations

2009 ◽  
Vol 48 (11) ◽  
pp. 4743-4752 ◽  
Author(s):  
Eric L. Klein ◽  
Andrei V. Astashkin ◽  
Dmitry Ganyushin ◽  
Christoph Riplinger ◽  
Kayunta Johnson-Winters ◽  
...  
Keyword(s):  
Density Functional ◽  
Direct Detection ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Density Functional Theory Calculations ◽  
Isotopic Labeling ◽  
Low Ph ◽  
Functional Theory ◽  
Modulation Spectroscopy

Formation and Direct Detection of Non-Conjugated Triplet 1,2-Biradical from β,γ-Vinylarylketone

2015 ◽  
Vol 68 (11) ◽  
pp. 1707 ◽  
Author(s):  
H. Dushanee M. Sriyarathne ◽  
Kosala R. S. Thenna-Hewa ◽  
Tianeka Scott ◽  
Anna D. Gudmundsdottir
Keyword(s):  
Rate Constant ◽  
Density Functional ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Direct Detection ◽  
Density Functional Theory Calculations ◽  
Laser Flash ◽  
Triplet Excited State ◽  
Functional Theory

Laser flash photolysis of 2-methyl-1-phenylbut-3-en-1-one (1) conducted at irradiation wavelengths of 266 and 308 nm results in the formation of triplet 1,2-biradical 2 that has λmax at 370 and 480 nm. Biradical 2 is formed with a rate constant of 1.1 × 107 s–1 and decays with a rate constant of 2.3 × 105 s–1. Isoprene-quenching studies support the notion that biradical 2 is formed by energy transfer from the triplet-excited state of the ketone chromophore of 1. Density functional theory calculations were used to verify the characterization of triplet biradical 2 and validate the mechanism for its formation. Thus, it has been demonstrated that intramolecular sensitization of simple alkenes can be used to form triplet 1,2-biradicals with the two radical centres localized on the adjacent carbon atoms.

P—N Bond Length Alterations Monitored by Infrared Absorption and Fourier Transform Raman Spectroscopy in Combination with Density Functional Theory Calculations

2003 ◽  
Vol 57 (8) ◽  
pp. 970-976 ◽  
Author(s):  
M. Bolboaca ◽  
T. Stey ◽  
A. Murso ◽  
D. Stalke ◽  
W. Kiefer
Keyword(s):  
Density Functional Theory ◽  
Fourier Transform ◽  
Density Functional ◽  
Structural Parameters ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Fourier Transform Raman Spectroscopy ◽  
Raman And Infrared Spectroscopy ◽  
Fourier Transform Raman

Fourier transform (FT) Raman and infrared spectroscopy in combination with density functional theory calculations have been applied to the vibrational characterization of the dimeric zinc diphenylphosphanyl(trimethylsilyl)amide complex [(Me3Si)2NZnPh2PNSiMe3]2 and the ortho-metallated species [Li( o-C6H4PPh2NSiMe3)]2·Et2O in relation to their parent starting materials diphenylphosphanyl (trimethylsilyl)amine Ph2P–N(H)SiMe3 and iminophosphorane Ph3P=NSiMe3. The spectroscopic changes evidenced in the spectra were correlated with the structural parameters in order to provide insight as to what extent the P–N bond is affected by the coordination to the metal center. The employment of density functional theory (DFT) calculations in addition to these spectroscopic methods offers the possibility of predicting whether the Lewis-basic imido nitrogen atom is involved in coordination not only in the solid state, but also in the gas phase.

scholarly journals A theoretical investigation on the isomerism and the NMR properties of thiosemicarbazones

2007 ◽  
Vol 5 (2) ◽  
pp. 396-419 ◽  
Author(s):  
N. Nuwan De Silva ◽  
Titus Albu
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
Intermolecular Hydrogen Bond ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
1H And 13C Nmr ◽  
Nmr Characterization ◽  
Hybrid Density Functional ◽  
Nmr Properties

AbstractHybrid density functional theory calculations at the mPW1PW91/6-31+G(d,p) level of theory have been used to investigate the optimized structures and other molecular properties of five different series of thiosemicarbazones. The investigated compounds were obtained from acenaphthenequinone, isatin and its derivatives, and alloxan. The focus of the study is the isomerism and the NMR characterization of these thiosemicarbazones. It was found that only one isomer is expected for thiosemicarbazones and methylthiosemicarbazones, while for dimethylthiosemicarbazones, two isomers are possible. All investigated thiosemicarbazones exhibit a hydrazinic proton that is highly deshielded and resonates far downfield in the proton NMR spectra. This proton is a part of a characteristic sixmembered ring, and its NMR properties are a result of its strong, intermolecular hydrogen bond. The relationships between the calculated 1H and 13C NMR chemical shifts and various geometric parameters are reported.

Characterization of Cu(II) Sites in Cu/SnO2 Catalysts by Electron Spin Echo Envelope Modulation Spectroscopy

1995 ◽  
Vol 99 (24) ◽  
pp. 9966-9973 ◽  
Author(s):  
Khalid Matar ◽  
Dongyuan Zhao ◽  
Daniella Goldfarb ◽  
Wan Azelee ◽  
Wayne Daniel ◽  
...  
Keyword(s):  
Electron Spin ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Modulation Spectroscopy ◽  
Envelope Modulation

scholarly journals Bottom-up Fabrication and Atomic-scale Characterization of Triply-linked, Laterally π-Extended Porphyrin Nanotapes

2021 ◽  
Author(s):  
Qiang Sun ◽  
Luis M. Mateos ◽  
Roberto Robles ◽  
Nicolas Lorente ◽  
Pascal Ruffieux ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Molecular Wires ◽  
Atomic Scale ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Scale Characterization ◽  
Low Solubility

<p>Porphyrin nanotapes (Por NTs) have attracted vast interest as potential molecular wires thanks to their exceptional electronic properties. Recently, Por NTs have been synthesized by solution-based methods, demonstrating high versatility and great potential for technological applications. However, their synthesis is tedious and their characterization limited by low solubility and stability. Here, we report the first example of meso-meso triply-fused Por NTs, which are prepared from a readily available Por precursor through a two-step synthesis on Au(111). The structural and electronic properties of individual Por NTs are addressed, both on Au(111) and on a thin insulating NaCl layer, by high-resolution scanning probe microscopy/spectroscopy complemented by density functional theory calculations.<br></p>

scholarly journals Synthesis and characterization of quaternary La(Sr)S–TaS2 misfit-layered nanotubes

2019 ◽  
Vol 10 ◽  
pp. 1112-1124 ◽  
Author(s):  
Marco Serra ◽  
Erumpukuthickal Ashokkumar Anumol ◽  
Dalit Stolovas ◽  
Iddo Pinkas ◽  
Ernesto Joselevich ◽  
...  
Keyword(s):  
Density Functional ◽  
Morphological Characteristics ◽  
Density Functional Theory Calculations ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Layered Compounds ◽  
Functional Theory ◽  
Resolution Electron ◽  
Structural Aspects

Misfit-layered compounds (MLCs) are formed by the combination of different lattices and exhibit intriguing structural and morphological characteristics. MLC Sr x La1− x S–TaS2 nanotubes with varying Sr composition (10, 20, 40, and 60 Sr atom %, corresponding to x = 0.1, 0.2, 0.4 and 0.6, respectively) were prepared in the present study and systematically investigated using a combination of high-resolution electron microscopy and spectroscopy. These studies enable detailed insight into the structural aspects of these phases to be gained at the atomic scale. The addition of Sr had a significant impact on the formation of the nanotubes with higher Sr content, leading to a decrease in the yield of the nanotubes. This trend can be attributed to the reduced charge transfer between the rare earth/S unit (La x Sr1− x S) and the TaS2 layer in the MLC which destabilizes the MLC lattice. The influence of varying the Sr content in the nanotubes was systematically studied using Raman spectroscopy. Density functional theory calculations were carried out to support the experimental observations.

scholarly journals Alkali metal adsorption on metal surfaces: new insights from new tools

2021 ◽  
Author(s):  
Arjun Raghavan ◽  
Louie Slocombe ◽  
Alexander Spreinat ◽  
David J. Ward ◽  
William Allison ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Alkali Metal ◽  
Metal Surfaces ◽  
Density Functional ◽  
Spin Echo ◽  
Density Functional Theory Calculations ◽  
Adsorption Site ◽  
Metal Adsorption ◽  
Functional Theory

A combined study of density functional theory calculations and 3He spin echo spectroscopy, finds sodium to change adsorption site on Ru(0001), from hollow to top, as the coverage is reduced.

Cleavage of an Iron-Silicon Bond by Hexamethylphosphoric Triamide: Synthesis and Characterization of [SiCl3(HMPA)3]+[Fe(CO)4SiCl3]–

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1553-1557 ◽  
Author(s):  
Van An Du ◽  
Stefan O. Baumann ◽  
Gregor N. Stipicic ◽  
Ulrich Schubert
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Synthesis And Characterization ◽  
Hexamethylphosphoric Triamide ◽  
Functional Theory ◽  
Iron Silicon

Addition of excess hexamethylphosphoric triamide (HMPA) to cis-Fe(CO)4(SiCl3)2 led to the exclusive formation of the new complex [SiCl3(HMPA)3]+ [Fe(CO)4SiCl3]− by cleavage of an ironsilicon bond. A reaction mechanism is presented, based on density functional theory calculations

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