نتایج جستجو برای: dft nmr

تعداد نتایج: 76720  

Journal: :Physical chemistry chemical physics : PCCP 2014
Cory M Widdifield Igor Moudrakovski David L Bryce

Calcium is the 5th most abundant element on earth, and is found in numerous biological tissues, proteins, materials, and increasingly in catalysts. However, due to a number of unfavourable nuclear properties, such as a low magnetogyric ratio, very low natural abundance, and its nuclear electric quadrupole moment, development of solid-state (43)Ca NMR has been constrained relative to similar nuc...

Journal: :Physical chemistry chemical physics : PCCP 2009
Cory M Widdifield David L Bryce

Solid-state NMR spectroscopy and GIPAW DFT calculations reveal the pronounced sensitivity of (79/81)Br and (25)Mg quadrupolar coupling constants to subtle aspects of solid state structure which were not previously detected by pXRD methods.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
Linda A Williams Neng Guo Alessandro Motta Massimiliano Delferro Ignazio L Fragalà Jeffrey T Miller Tobin J Marks

Structural characterization of the catalytically significant sites on solid catalyst surfaces is frequently tenuous because their fraction, among all sites, typically is quite low. Here we report the combined application of solid-state (13)C-cross-polarization magic angle spinning nuclear magnetic resonance ((13)C-CPMAS-NMR) spectroscopy, density functional theory (DFT), and Zr X-ray absorption...

2016
Arantxa Fernandes David McKay Scott Sneddon Daniel M. Dawson Sebastian Lawson Richard Veazey Karl R. Whittle Sharon E. Ashbrook

An NMR crystallographic approach, involving the combination of 119Sn NMR spectroscopy, XRD, and DFT calculations, is demonstrated for the characterization of La2Sn2-x Ti x O7 ceramics. A phase change from pyrochlore (La2Sn2O7) to a layered perovskite phase (La2Ti2O7) is predicted (by radius ratio rules) to occur when x ≈ 0.95. However, the sensitivity of NMR spectroscopy to the local environmen...

Journal: :Chemical communications 2005
Aled L Jones G Sean McGrady Peter Sirsch Jonathan W Steed

Ruthenium trihydrides containing N-heterocyclic carbene ligands display large quantum mechanical exchange couplings in their 1H NMR spectra: DFT calculations are used to explore this phenomenon and to compare them to their phosphine congeners.

Journal: :Chemical communications 2011
Sophia A Solomon F Matthias Bickelhaupt Richard A Layfield Mathias Nilsson Jordi Poater Miquel Solà

A donor-functionalized, silyl-substituted pentadienyllithium has been synthesized and characterized by crystallography and NMR spectroscopy. The pentadienyl negative charge was found to be partially localized, which DFT revealed to be due to the polarizing power of the lithium cation.

Journal: :Chemical communications 2012
Anmin Zheng Bing Han Bojie Li Shang-Bin Liu Feng Deng

Solid-state NMR and DFT calculation studies certified the presence of an intermolecular solvent effect for molecules confined in microporous zeolite, leading to a notable increase in Brønsted acidity of the solid acid catalyst.

Journal: :The journal of physical chemistry. B 2016
Xianqi Kong Andreas Brinkmann Victor Terskikh Roderick E Wasylishen Guy M Bernard Zhuang Duan Qichao Wu Gang Wu

We report a combined solid-state (1H, 2H, 13C, 17O) NMR and plane-wave density functional theory (DFT) computational study of the O···H···O low-barrier hydrogen bonds (LBHBs) in two 1,3-diketone compounds: dibenzoylmethane (1) and curcumin (2). In the solid state, both 1 and 2 exist in the cis-keto-enol tautomeric form, each exhibiting an intramolecular LBHB with a short O···O distance (2.435 Å...

Journal: :journal of physical & theoretical chemistry 2011
m. sayadian l. pishkar f. mollaamin

calixarenes are a readily available and important class of macrocycles in supramolecularchemistry. calixarenes have generated considerable interest due to their basket shaped structureand as useful building blocks to synthesize selective receptors for the guest species, notably alkali,alkaline earth, lanthanide and transition metal cations. in this work studied on the complexingproperties of a ...

Journal: :Organometallics 2021

A series of anionic ruthenium pentahydride complexes with the general formula [M(THF)x][RuH5(PCy3)2] (M = Li, Na, K) were synthesized. Their characterization by multinuclear NMR, IR, X-ray diffraction, and DFT techniques show that these can adopt different structural features (monomer/dimer, cis/trans phosphines, hydride/dihydrogen ligands) depending on countercation, solvent, and/or temperatur...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید