Quantum-Chemical Simulation of <sup>1</sup>H NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton–Proton Coupling Constants in Organic Molecules

Bally, Thomas; Rablen, Paul R.

doi:10.1021/jo200513q

Cited by 184 publications

(211 citation statements)

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“…Basis functions with angular momenta up to g are supported. Predictions of good accuracy for J-couplings can be obtained [106,107] especially when using specialised basis sets [108][109][110][111], several of which have been added to the basis set library.…”

Section: Electric and Magnetic Molecular Propertiesmentioning

confidence: 99%

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Shao¹,

Gan²,

Epifanovsky³

et al. 2014

Molecular Physics

2,746

2,077

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A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and openshell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr 2 dimer, exploring zeolitecatalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.Keywords quantum chemistry, software, electronic structure theory, density functional theory, electron correlation, computational modelling, Q-Chem Disciplines Chemistry CommentsThis article is from Molecular Physics: An International Journal at the Interface Between Chemistry and Physics 113 (2015): 184, doi:10.1080/00268976.2014. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Authors 185A summary of the technical advances that are incorporated in the fourth major release of the Q-CHEM quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly corre...

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Section: Electric and Magnetic Molecular Propertiesmentioning

confidence: 99%

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Shao¹,

Gan²,

Epifanovsky³

et al. 2014

Molecular Physics

2,746

2,077

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“…22 1 H− 1 H coupling constants of the lowest-energy conformers were calculated at the B3LYP-SCRF/6-31G(d,p)u+1s (using only the Fermi contact term)//B3LYP-SCRF/6-31G(d,p) level in acetone (PCM). 23 Calculated NMR chemical shifts and 1 H− 1 H coupling constants were linearly corrected for the experimental data. All DFT calculations were carried out using Gaussian 09.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Diastereomeric Ellagitannin Isomers from Penthorum chinense

et al. 2015

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From the dried stem of Penthorum chinense (Penthoraceae), 1-O-galloyl-4,6-(R)-hexahydroxydiphenoyl (HHDP)-β-D-glucose and 2',4',6'-trihydroxyacetophenone 4'-O-[4,6-(R)-HHDP]-β-D-glucoside were isolated together with their (S)-HHDP isomers. Ellagitannins with a 4,6-(S)-HHDP-glucose moiety are widely distributed in the plant kingdom; however, 4,6-(R)-HHDP glucoses are extremely rare. Lowest-energy conformers of 1-O-galloyl-(S)- and (R)-HHDP-glucopyranoses were derived by density functional theory calculations, and the calculated (1)H and (13)C NMR chemical shifts and the (1)H-(1)H coupling constants were in agreement with the experimental values. The results revealed a conformational difference of the diastereomeric macrocyclic ester rings. In addition, a new compound, 1',3',5'-trihydroxybenzene 1'-O-[4,6-(S)-HHDP]-β-D-glucoside, was also isolated.

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“…Of the three important classes of primary NMR data-chemical shifts, coupling constants and relative integrated signal intensity-the first is the most diagnostic of the local chemical and magnetic environment (i.e., the nuclei's structural surroundings) and, arguably, the most reliably addressable by computational methods 1,2 . Accordingly, this protocol deals only with computational aspects of chemical shifts, and only proton and carbon nuclei are considered.…”

Section: Introductionmentioning

confidence: 99%

A guide to small-molecule structure assignment through computation of (1H and 13C) NMR chemical shifts

2014

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this protocol is intended to provide chemists who discover or make new organic compounds with a valuable tool for validating the structural assignments of those new chemical entities. experimental 1 H and/or 13 c nMr spectral data and its proper interpretation for the compound of interest is required as a starting point. the approach involves the following steps: (i) using molecular mechanics calculations (with, e.g., MacroModel) to generate a library of conformers; (ii) using density functional theory (DFt) calculations (with, e.g., Gaussian 09) to determine optimal geometry, free energies and chemical shifts for each conformer; (iii) determining Boltzmann-weighted proton and carbon chemical shifts; and (iv) comparing the computed chemical shifts for two or more candidate structures with experimental data to determine the best fit. For a typical structure assignment of a small organic molecule (e.g., fewer than ~10 non-H atoms or up to ~180 a.m.u. and ~20 conformers), this protocol can be completed in ~2 h of active effort over a 2-d period; for more complex molecules (e.g., fewer than ~30 non-H atoms or up to ~500 a.m.u. and ~50 conformers), the protocol requires ~3-6 h of active effort over a 2-week period. to demonstrate the method, we have chosen the analysis of the cis-versus the trans-diastereoisomers of 3-methylcyclohexanol (1-cis versus 1-trans). the protocol is written in a manner that makes the computation of chemical shifts tractable for chemists who may otherwise have only rudimentary computational experience. this method certainly has value, the example described next shows that when one moves to the consideration of molecules bearing more than one stereocenter, this approach is no longer adequate.Consider the case of the trans-versus the cis-diastereomers of 3-methylcyclohexanol (1-trans and 1-cis, respectively). The experimental 1 H NMR spectra for 1-trans and 1-cis are shown in Figure 1a,b (see Supplementary Data 1 for a full listing of actual chemical shift values). There are substantial differences in these two spectra, especially within the upfield 0.7-2.1 p.p.m. range. Clearly, it would be valuable if computational approaches could reproduce these sorts of differences sufficiently well to allow confident assignment of structure.Common software packages that use empirical (often increment-based) compilations of chemical shift information (e.g., tabulated shift increments or databases of known spectral data) allow users to predict the chemical shifts of a given input structure. These include 'ChemNMR' within ChemBioDraw (also known as ChemDraw) and 'C+H NMR Predictor and DB' within the ACD/Labs software suite. These methods sometimes can be sufficient for the task of resolving constitutional structural assignments. However, when issues associated with relative configuration are considered, increment-based methods are decidedly ill-equipped. Analysis of structures 1-trans and 1-cis by each of these programs quickly reveals these limitations, even for these simple structures. Namely, because Che...

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Quantum-Chemical Simulation of ¹H NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton–Proton Coupling Constants in Organic Molecules

Cited by 184 publications

References 40 publications

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Diastereomeric Ellagitannin Isomers from Penthorum chinense

A guide to small-molecule structure assignment through computation of (1H and 13C) NMR chemical shifts

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Quantum-Chemical Simulation of 1H NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton–Proton Coupling Constants in Organic Molecules

Cited by 184 publications

References 40 publications

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Diastereomeric Ellagitannin Isomers from Penthorum chinense

A guide to small-molecule structure assignment through computation of (1H and 13C) NMR chemical shifts

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Product

Resources

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Quantum-Chemical Simulation of ¹H NMR Spectra. 2. Comparison of DFT-Based Procedures for Computing Proton–Proton Coupling Constants in Organic Molecules