Review on DFT and ab initio Calculations of Scalar Coupling Constants

Alkorta, Ibón; Elguero, José

doi:10.3390/i4030064

Cited by 80 publications

(28 citation statements)

References 110 publications

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“…Note that this 1 H– 19 F coupling can be through-bonds, i.e. a 5 J or through-space, a common problem involving 19 F [19–20]. Starting from the F9 assignment, the ( 19 F– 19 F) COSY experiments permitted to establish the correlation F9–F8–F7–F6, in both compounds.…”

Section: Resultsmentioning

confidence: 99%

“…Some couplings involving the fluorine atoms are not well reproduced by the calculations, this is particularly apparent for the 1 J CF , that are overestimated, in absolute value, by about 68 Hz. The overestimation and difficulty to calculate coupling constants involving 19 F has been reported several times [20,22–23]. …”

Section: Resultsmentioning

confidence: 99%

“…The barriers for an AB system that become an A 2 one depend on three values: i) the coalescence temperature T C ; ii) the difference in Hz of the protons of the AB system (Δ ν AB ), and iii) the geminal coupling constant, J AB (or J ae ). The inversion rate at the coalescence temperature for an AB system is given by k C = π/√2·√Δ ν 2 + 6 J AB 2 [11] and the barrier by the modified Eyring equation [24–26], Δ G ‡ = 19.12· T C (10.32 + log T C / k C ) [18–20]. From the values in Table 4 we have determined the corresponding experimental inversion barriers.…”

Section: Resultsmentioning

confidence: 99%

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Structure of 1,5-benzodiazepinones in the solid state and in solution: Effect of the fluorination in the six-membered ring

Pérez‐Torralba¹,

Claramunt

García³

et al. 2013

Beilstein J. Org. Chem.

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SummaryTwo novel tetrafluorinated 1,5-benzodiazepinones were synthesized and their X-ray structures determined. 6,7,8,9-Tetrafluoro-4-methyl-1,3-dihydro-2H-1,5-benzodiazepin-2-one crystallizes in the monoclinic P21/c space group and 6,7,8,9-tetrafluoro-1,4-dimethyl-1,3-dihydro-2H-1,5-benzodiazepin-2-one in the triclinic P−1 space group. Density functional theory studies at the B3LYP/6-311++G(d,p) level were carried out on these compounds and on four non-fluorinated derivatives, allowing to calculate geometries, tautomeric energies and ring-inversion barriers, that were compared with the experimental results obtained by static and dynamic NMR in solution and in solid state.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Structure of 1,5-benzodiazepinones in the solid state and in solution: Effect of the fluorination in the six-membered ring

Pérez‐Torralba¹,

Claramunt

García³

et al. 2013

Beilstein J. Org. Chem.

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“…Another valuable field-based method is the polymer reference interaction site model (PRISM) which attempts to realize the polymer structure in terms of density correlation functions [ 38 ]. Other examples of such methods include density functional theory (DFT) [ 38 , 39 , 40 ], self-consistent field theory (SCFT) [ 32 , 33 , 38 ], and phase-field techniques [ 41 , 42 , 43 ]. In this section, we outline the details of some of the most important methods at different scales.…”

Section: Simulation Methodsmentioning

confidence: 99%

A Review of Multiscale Computational Methods in Polymeric Materials

2017

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Polymeric materials display distinguished characteristics which stem from the interplay of phenomena at various length and time scales. Further development of polymer systems critically relies on a comprehensive understanding of the fundamentals of their hierarchical structure and behaviors. As such, the inherent multiscale nature of polymer systems is only reflected by a multiscale analysis which accounts for all important mechanisms. Since multiscale modelling is a rapidly growing multidisciplinary field, the emerging possibilities and challenges can be of a truly diverse nature. The present review attempts to provide a rather comprehensive overview of the recent developments in the field of multiscale modelling and simulation of polymeric materials. In order to understand the characteristics of the building blocks of multiscale methods, first a brief review of some significant computational methods at individual length and time scales is provided. These methods cover quantum mechanical scale, atomistic domain (Monte Carlo and molecular dynamics), mesoscopic scale (Brownian dynamics, dissipative particle dynamics, and lattice Boltzmann method), and finally macroscopic realm (finite element and volume methods). Afterwards, different prescriptions to envelope these methods in a multiscale strategy are discussed in details. Sequential, concurrent, and adaptive resolution schemes are presented along with the latest updates and ongoing challenges in research. In sequential methods, various systematic coarse-graining and backmapping approaches are addressed. For the concurrent strategy, we aimed to introduce the fundamentals and significant methods including the handshaking concept, energy-based, and force-based coupling approaches. Although such methods are very popular in metals and carbon nanomaterials, their use in polymeric materials is still limited. We have illustrated their applications in polymer science by several examples hoping for raising attention towards the existing possibilities. The relatively new adaptive resolution schemes are then covered including their advantages and shortcomings. Finally, some novel ideas in order to extend the reaches of atomistic techniques are reviewed. We conclude the review by outlining the existing challenges and possibilities for future research.

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“…[20] Bagno, Saielli, and Scorrano [21] Scheme 6 6 Ab initio Calculations on Supramolecular Systems calculated through-space J HH and J CH coupling constants for a calix [4]arene-acetonitrile complex (2-CH 3 CN). The coupling occurs between the methyl group of the guest and the neighbouring benzene rings of the calix [4]arene.…”

Section: Methodsmentioning

confidence: 99%