نتایج جستجو برای: dft nmr

تعداد نتایج: 76720  

Journal: :The journal of physical chemistry. B 2009
Licínia L G Justino M Luísa Ramos Paulo E Abreu Rui A Carvalho Abilio J F N Sobral Ullrich Scherf Hugh D Burrows

Relationships have been obtained between intermonomer torsional angle and NMR chemical shifts ((1)H and (13)C) for isolated chains of two of the most important poly(9,9-dialkylfluorenes), poly[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (PF2/6) and the copolymer poly(9,9-dioctylfluorene-co-[2,1,3]benzothiadiazole-4,7-diyl) (F8BT), using DFT calculations. The correlations provide a model for NMR spe...

Journal: :Journal of the American Chemical Society 2004
David L Bryce Jérôme Boisbouvier Ad Bax

Magnetic susceptibility anisotropies (Deltachi) are determined for the nucleic acid bases on the basis of a combined NMR spectroscopic and DFT study. Magnetic field-induced residual dipolar couplings (RDC) measured for the Dickerson dodecamer allow for the determination of a precise value of Deltachi for this DNA. A tensor summation employing the results of DFT calculations of the individual ba...

Journal: :Journal of magnetic resonance 2001
G S Armstrong V A Mandelshtam

We present a linear algebraic method, named the eXtended Fourier Transform (XFT), for spectral estimation from truncated time signals. The method is a hybrid of the discrete Fourier transform (DFT) and the regularized resolvent transform (RRT) (J. Chen et al., J. Magn. Reson. 147, 129-137 (2000)). Namely, it estimates the remainder of a finite DFT by RRT. The RRT estimation corresponds to solut...

Journal: :Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2012
Hamit Alyar Arslan Ünal Neslihan Özbek Saliha Alyar Nurcan Karacan

A conformational analysis of the methanesulfonamide-N,N'-1,2-ethanediylbis (msen) was performed by using vibrational and NMR spectroscopies as well as theoretical computations. The possible stable conformers of msen on its potential energy surface were investigated by semi-empirical PM5 method and appropriate structures were defined with B3LYP hybrid density functional theory (DFT) method along...

Journal: :The Journal of chemical physics 2015
Taye B Demissie Michał Jaszuński Stanislav Komorovsky Michal Repisky Kenneth Ruud

We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and no...

Abstractl Density functional theory (DFT) was used to investigate the effects of intra-moecular interactions and implicit water molecules on the relative stability and the NMR shielding tensors of hallucinogenic harmine in the monomeric and dimeric states. Results represented that the relative stability and the NMR shielding tensors are dependent on the resonance interactions and chemical envir...

Journal: :Chemical communications 2007
David R Armstrong William Clegg Sophie H Dale David V Graham Eva Hevia Lorna M Hogg Gordon W Honeyman Alan R Kennedy Robert E Mulvey

Benzene can be easily 1,4-dideprotonated stoichiometrically on reaction with two equivalents of a synergic mixture of tBu2Zn, NaTMP and TMEDA to give a unique 1,4-dizincated benzene product which has been characterised by X-ray crystallography and NMR spectroscopy as well as modelled theoretically by DFT computational studies; a related synergic dimagnesiation of benzene is also reported.

Journal: :Chemical communications 2011
Caroline M Knapp Joseph S Large Nicholas H Rees Jose M Goicoechea

Reaction of K(3)P(7), FeCl(2), [NH(4)][B(C(6)H(5))(4)] and 2,2,2-crypt yielded the unprecedented cluster dianion [Fe(HP(7))(2)](2-). This species was characterized by single crystal X-ray diffraction, multielement NMR spectroscopy and electrospray mass-spectrometry. DFT calculations on the dianion were also conducted.

2013
David J Shepherd Phillip A Broadwith Bryony S Dyson Robert S Paton Jonathan W Burton

The originally assigned stereostructures of laurefurenynes A and B have been reassigned on the basis of DFT calculations of NMR chemical shifts, synthesis of model compounds and total synthesis of laurefurenyne B, demonstrating the power of this combined approach for stereostructure elucidation/confirmation.

Journal: :Dalton transactions 2014
Celedonio M Álvarez Luis A García-Escudero Raúl García-Rodríguez Jose M Martín-Álvarez Daniel Miguel Víctor M Rayón

The geometry imposed by the coordination sphere around the metal, together with the choice of the "arms" can be advantageously used to build corannulene-based molecular tweezers, which show great affinities for C60 and C70, as revealed by NMR titration experiments, mass spectroscopy, DFT calculations and the single crystal X-ray structural analysis of the compound C60 ⊂1.

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