نتایج جستجو برای: nmr shielding

تعداد نتایج: 67435  

E. Pournamdari M. Monajjemi

BCN compounds have been researched theoretically and experimentally widely. In this paper, weintroduce the theoretical prediction of ternary B-C-N compounds. NMR spectroscopy was employedextensively to study these ternary nanostructures. We discuss the utilization of chemical shiftinformation as well as ab initio calculations of nuclear shielding for H20134C9N4 structuredetermination. We calcul...

Journal: :Physical chemistry chemical physics : PCCP 2011
Janusz Cukras Joanna Sadlej

We employ state-of-the-art methods and basis sets to study the effect of inserting the Xe atom into the water molecule and the water dimer on their NMR parameters. Our aim is to obtain predictions for the future experimental investigation of novel xenon complexes by NMR spectroscopy. Properties such as molecular structure and energetics have been studied by supermolecular approaches using HF, M...

Journal: :Physical chemistry chemical physics : PCCP 2009
Joseph Zakzeski Sarah Burton Andrew Behn Martin Head-Gordon Alexis T Bell

A spectroscopic investigation of complexes used to catalyze the oxidative carbonylation of toluene to p-toluic acid was conducted. Rhodium complexes were analyzed by (103)Rh and (13)C NMR, UV-visible spectroscopy, and infrared spectroscopy. In the presence of vanadium and oxygen, the resting state of the Rh-catalyst was found to exist as a Rh(III) complex with carbonyl and trifluoroacetate liga...

2007
L. Benda

Abstract. DFT quantum-chemical calculations were carried out for the cationic, zwitterionic and anionic form of the L-Alanyl-L-Alanine di-peptide that can be experimentally accessed at different pH. The N NMR chemical shielding tensor of the amide nitrogen was used for theoretical modeling of the cross-correlated relaxations. In particular, effective chemical shielding anisotropies (effective C...

Journal: :Physical chemistry chemical physics : PCCP 2013
Jarkko Vähäkangas Suvi Ikäläinen Perttu Lantto Juha Vaara

Nuclear magnetic resonance (NMR) data for graphenes are mainly lacking in the literature. We provide quantitative first-principles quantum-chemical calculations of NMR chemical shifts and shielding anisotropies as well as spin-spin couplings and anisotropies for increasingly large, hexagon-like fragments of graphene, hydrogenated graphene (graphane) and fluorinated graphene (fluorographene). Du...

2015
Robert Laskowski Peter Blaha

We present calculations of solid state NMR magnetic shielding in metals, which includes both the orbital and the complete spin response of the system in a consistent way. The latter contains an induced spin-polarization of the core states and needs an all-electron self-consistent treatment. In particular, for transition metals, the spin hyperfine field originates not only from the polarization ...

2017
Khoong Hong Khoo Robert Laskowski Peter Blaha

The results of first-principles calculations of Al and Sc NMR shielding for a set of ScTT′Al Heusler phase compounds are reported and compared to recently published experimental NMR shifts. The orbital component of the shielding (chemical shift) is computed using density functional perturbation formalism. The spin part (Knight shift) is evaluated using a direct self-consistent approach, where a...

Journal: :journal of physical & theoretical chemistry 2012
m. monajjemi m. ahmadianarog

sulforaphane, an isothiocyanate found in broccoli and other cruciferous vegetables. it is an antioxidantand anti-cancer agent, and reduces blood pressure, and also has anti-allergic effects.in this article, six theoretical methods have been used for calculation of physical parameters insolforaphane and several similar compounds. we calculated physical parameters like atomic charges.energy (ae) ...

Journal: :Solid state nuclear magnetic resonance 2008
Robin K Harris Edwin D Becker Sonia M Cabral De Menezes Pierre Granger Roy E Hoffman Kurt W Zilm

IUPAC has published a number of recommendations regarding the reporting of nuclear magnetic resonance (NMR) data, especially chemical shifts. The most recent publication [Pure Appl. Chem. 73, 1795 (2001)] recommended that tetramethylsilane (TMS) serve as a universal reference for reporting the shifts of all nuclides, but it deferred recommendations for several aspects of this subject. This docu...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2006
Dariush Ajami Tetsuo Iwasawa Julius Rebek

Self-assembled capsules are hosts that recognize and surround smaller molecule guests of appropriate size, shape, and chemical surfaces. The space available inside is a cage of fixed solvent molecules, many of which are aromatic. These aromatics provide anisotropic shielding to guests, and a map of induced magnetic shielding for the inner space can be obtained through nucleus-independent chemic...

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