Theory and computation of nuclear shielding

Kupka, Teobald

doi:10.1039/9781788010665-00001

Cited by 10 publications

(5 citation statements)

References 169 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Due to the central importance of NMR spectroscopy in chemistry and related fields, the quantum-chemical calculation of NMR parameters has become a tool of appreciable importance and interest . Methodological improvements in this area in terms of the computational efficiency , , accuracy, − and method validation − are currently being pursued very actively. With the focus of the present work on nuclear shieldings, we note that Kohn–Sham density functional theory (DFT) is the most widely used methodology in view of its good cost–performance ratio.…”

Section: Introductionmentioning

confidence: 99%

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Schattenberg

Kaupp

2021

J. Phys. Chem. A

View full text Add to dashboard Cite

A recently reported coupled-perturbed Kohn–Sham implementation to compute nuclear shielding constants with gauge-including atomic orbitals and local hybrid functionals has been extended to cover higher derivatives of the density in the local mixing function (LMF) of the local hybrid as well as the calibration function (CF) needed to deal with the ambiguity of exchange-energy densities. This allowed the first evaluation of state-of-the-art local hybrids with “calibrated” exchange-energy densities for nuclear shieldings. Compared to previously evaluated simpler local hybrids without a CF, appreciable improvements are found for proton shieldings. Furthermore, the recent LH20t functional is still competitive with the outstanding performance of the uncalibrated LH12ct-SsirSVWN and LH12ct-SsifSVWN LHs for heavier nuclei, suggesting that LH20t is possibly the most robust choice of any rung-four functional for computing the nuclear shieldings of main-group nuclei so far. Interestingly, the presence of a CF in the functional significantly reduces the number of artifacts introduced by the widely used Maximoff–Scuseria framework to treat the local kinetic energy τ. The latter occurs in so-called t-LMFs used in many of the present local hybrids. In any case, the use of Dobson’s current-density functional framework is also recommended with more advanced calibrated τ-dependent local hybrid functionals.

show abstract

Section: Introductionmentioning

confidence: 99%

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Schattenberg

Kaupp

2021

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…Resonance stabilization effects can be recouped to some extent by combining computed Δ E σ/σ* (C–H) and 1 H NMR chemical shift (δ) values into a composite descriptor, which we have termed the Electronic Activation Index (EAI, Figure b). Although 1 H NMR δ do depend intimately on inductive deshielding, resonance stabilization effects on C–H insertion are also captured indirectly, since neighboring electronegative atoms invariably have lone pairs that can stabilize positive charge buildup at α-carbon atoms through resonance (see Supporting Information for further discussion). Similarly, anisotropic effects of alkene and aryl π-systems also result in relatively downfield 1 H NMR shifts that track with increased propensity for transition state stabilization in allylic and benzylic C–H insertions, respectively. , …”

Section: Resultsmentioning

confidence: 99%

Leveraging Regio- and Stereoselective C(sp³)–H Functionalization of Silyl Ethers to Train a Logistic Regression Classification Model for Predicting Site-Selectivity Bias

et al. 2022

View full text Add to dashboard Cite

The C−H functionalization of silyl ethers via carbene-induced C−H insertion represents an efficient synthetic disconnection strategy. In this work, site-and stereoselective C(sp 3 )−H functionalization at α, γ, δ, and even more distal positions to the siloxy group has been achieved using donor/ acceptor carbene intermediates. By exploiting the predilections of Rh 2 (R-TCPTAD) 4 and Rh 2 (S-2-Cl-5-BrTPCP) 4 catalysts to target either more electronically activated or more spatially accessible C− H sites, respectively, divergent desired products can be formed with good diastereocontrol and enantiocontrol. Notably, the reaction can also be extended to enable desymmetrization of meso silyl ethers. Leveraging the broad substrate scope examined in this study, we have trained a machine learning classification model using logistic regression to predict the major C−H functionalization site based on intrinsic substrate reactivity and catalyst propensity for overriding it. This model enables prediction of the major product when applying these C−H functionalization methods to a new substrate of interest. Applying this model broadly, we have demonstrated its utility for guiding late-stage functionalization in complex settings and developed an intuitive visualization tool to assist synthetic chemists in such endeavors.

show abstract

“…To find the stability of the structure, harmonic vibrational frequency analyses were carried out at the same computational level of theory. The chemical shift calculations for NMR were performed using the gauge-independent atomic orbital (GIAO) [ 55 ] method at the WB97XD LANL2DZ. All of the stable structures were found to be at energy minima with the lowest possible positive frequencies.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Biological Studies of Novel Aminophosphonates and Their Metal Carbonyl Complexes (Fe, Ru)

Kosińska

Virieux

Pirat

et al. 2022

IJMS

View full text Add to dashboard Cite

The quest to find new inhibitors of biologically relevant targets is considered an important strategy to introduce new drug candidates for the treatment of neurodegenerative diseases. A series of (aminomethyl)benzylphosphonates 8a–c and their metallocarbonyl iron 9a–c and ruthenium 10a–c complexes were designed, synthesized, and evaluated for their inhibitory potentials against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by determination of IC50. Metallocarbonyl derivatives, in general, did not show significant inhibition activity against these enzymes, the most potent inhibitor was the (aminomethyl)benzylphosphonate 8a (IC50 = 1.215 µM against AChE). Molecular docking analysis of AChE and (aminomethyl)benzylphosphonates 8a–c showed the strongest interactions of 8a and AChE compared to isomers 8b and 8c. Cytotoxicity studies of synthesized compounds towards the V79 cell line were also performed and discussed.

show abstract

Theory and computation of nuclear shielding

Cited by 10 publications

References 169 publications

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Leveraging Regio- and Stereoselective C(sp³)–H Functionalization of Silyl Ethers to Train a Logistic Regression Classification Model for Predicting Site-Selectivity Bias

Synthesis and Biological Studies of Novel Aminophosphonates and Their Metal Carbonyl Complexes (Fe, Ru)

Contact Info

Product

Resources

About

Theory and computation of nuclear shielding

Cited by 10 publications

References 169 publications

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Implementation and Validation of Local Hybrid Functionals with Calibrated Exchange-Energy Densities for Nuclear Shielding Constants

Leveraging Regio- and Stereoselective C(sp3)–H Functionalization of Silyl Ethers to Train a Logistic Regression Classification Model for Predicting Site-Selectivity Bias

Synthesis and Biological Studies of Novel Aminophosphonates and Their Metal Carbonyl Complexes (Fe, Ru)

Contact Info

Product

Resources

About

Leveraging Regio- and Stereoselective C(sp³)–H Functionalization of Silyl Ethers to Train a Logistic Regression Classification Model for Predicting Site-Selectivity Bias