Hydrogen Bonding in Crystalline Organic Solids

Brown, Steven P.

doi:10.1002/9780470034590.emrstm1006

Cited by 6 publications

(7 citation statements)

References 38 publications

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“…According to Figure 4, it is possible to confirm that the hydrogen bonded to selenium in NaHSe is more distant in the solvent PEG-400 than in EtOH, because the chemical shift of selenium-77 in PEG-400 medium is deshielded compared to that in EtOH. When the hydrogen atom is closer to selenium, or to another atom, [73] the electronic density around selenium increases. Consequently, if the selenium-77 chemical shift is shielded, the nucleophilicity will decrease, as observed using EtOH as the solvent.…”

Section: Se Nmr Spectroscopy In Organic Synthesismentioning

confidence: 99%

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

et al. 2020

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This review article deals with organic synthesis from the perspective of selenium-77 nuclear magnetic resonance (NMR) spectroscopy. Different types of organic reactions are briefly discussed, incorporating mechanism aspects through 77 Se NMR observable intermediates and byproducts. The 77 Se NMR experiments are demonstrated in terms of structural characterization and new insights for organic reactions. The ability to visualize different molecules in a reaction mixture provides a facile and versatile route for the development of synthetic organoselenium compounds. Thus, the review describes the strategies accomplished mainly in the past five years in the syntheses and applications of the organoselenium compounds, focusing on 77 Se NMR spectroscopy.

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Section: Se Nmr Spectroscopy In Organic Synthesismentioning

confidence: 99%

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

et al. 2020

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“…NMR has been widely used to study the rich polymorphism that is often found for molecular systems, as the chemical shift is a very sensitive probe of the local environment (including both the covalent bonds that are formed and the spatial proximity of other nuclei). [221][222][223][224][225][226] As such, this can provide information not just on molecular structure (as in solution-state NMR) but also on the spatial arrangement of molecules in the solid state (i.e., the crystal packing), and the number of distinct molecules within a structure. Figure 22a shows 13 C CP MAS spectra of two forms of finasteride.…”

Section: Molecular Systemsmentioning

confidence: 99%

“…As an example, Figure 22b shows two-dimensional 15 N homonuclear correlation spectra of deoxyguanosine derivatives. [226,233] The pairs of peaks either side of the diagonal indicate an interaction between two nuclei, and while most signals result from intramolecular interactions, the correlations highlighted (N1-N7 and N2-N7) provide information on the intermolecular hydrogen bonds present and the self-assembly of the molecules into ribbons or quartets. More recently, intermolecular J couplings have been observed between chalcogen-containing aromatic molecules.…”

Section: Molecular Systemsmentioning

confidence: 99%

Exploiting NMR spectroscopy for the study of disorder in solids

Moran

Dawson

Ashbrook

2017

International Reviews in Physical Chemistry

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Although the solid state is typically characterised by inherent periodicity, many interesting physical and chemical properties of solids arise from a variation in this, i.e., changes in the nature of the atom occupying a particular site in a crystal structure or variation in the position of an atom (or group of atoms) in different parts of a structure, or variation as a function of time. This lack of long-range order poses significant challenges, not just for the characterisation of the structure of disordered materials, but also simply for its description. The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local, atomic-scale environment, without the requirement for long-range order, makes it a powerful tool for the study of disorder in the solid state. Information on the number and type(s) of coordinating atoms or through-space and through-bond connectivity between atomic species enables the construction of a detailed picture of the structure. After a brief description of the background theory of NMR spectroscopy, and the experimental methods employed, we will describe the effects of disorder on NMR spectra and the use of calculations to help interpret experimental measurements. We will then review a range of applications to different types of disordered materials, including oxides and ceramics, minerals, porous materials, biomaterials, energy materials, pharmaceuticals, polymers and glasses. We will discuss the most successful approaches for studying different materials, and illustrate the type of information available and the structural insight gained.

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“…In particular, their neutron data suggest that the enolic proton in dibenzoylmethane is asymmetrically located between the two O atoms and its position is insensitive to temperature, whereas the X-ray data show a gradual change of hydrogen bonding from being asymmetric at low temperatures to essentially symmetric at room temperature. Notably, solid-state NMR data should be sensitive to both the nuclear position and electronic structure in hydrogen bonding systems. − However, a unified picture of the H atom behavior in an LBHB that can reconcile diffraction and solid-state NMR results is still lacking. In addition to the most stable orthorhombic polymorph (I) of dibenzoylmethane, two different polymorphs have also been reported in the literature. , …”

Section: Introductionmentioning

confidence: 99%

Proton Probability Distribution in the O···H···O Low-Barrier Hydrogen Bond: A Combined Solid-State NMR and Quantum Chemical Computational Study of Dibenzoylmethane and Curcumin

et al. 2016

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We report a combined solid-state (H, H,C, O) 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 in 1 and 2.455 Å in 2). Whereas numerous experimental (structural and spectroscopic) and computational studies have been reported for the enol isomers of 1,3-diketones, a unified picture about the proton location within an LBHB is still lacking. This work reports for the first time the solid-stateO NMR data for the O···H···O LBHBs in 1,3-diketones. The central conclusion of this work is that detailed information about the probability density distribution of the proton (nuclear zero-point motion) across an LBHB can be obtained from a combination of solid-state NMR and plane-wave DFT computations (both NMR parameter calculations and ab initio molecular dynamics simulations). We propose that the precise proton probability distribution across an LBHB should provide a common basis on which different and sometimes seemingly contradicting experimental results obtained from complementary techniques, such as X-ray diffraction, neutron diffraction, and solid-state NMR, can be reconciled.

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Hydrogen Bonding in Crystalline Organic Solids

Cited by 6 publications

References 38 publications

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

Exploiting NMR spectroscopy for the study of disorder in solids

Proton Probability Distribution in the O···H···O Low-Barrier Hydrogen Bond: A Combined Solid-State NMR and Quantum Chemical Computational Study of Dibenzoylmethane and Curcumin

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