deshielding

Bonding electrons can also lead to shielding and deshielding effects.

Trends in chemical shift are explained based on the degree of shielding or deshielding.

This unusual deshielding presumably reflects a proximity effect between a methyl group and the hydrogen atom attached to the sp3 carbon of the adducts.

Shielding and deshielding due to γ and δ steric interactions were observed depending on the substituent.

An unusually large anisotropic effect of the antipyryl group, causing a deshielding of the closest proton on the quinoneimide ring, has been found.

Nuclear magnetic resonance data for all the zinc complexes indicate a significant deshielding of one benzene ring proton on each coordinated benzimidazole group.

Deshielding changes characterize a syn-diaxial orientation of hydroxyl groups, and also of a hydroxyl group with respect to the bridgehead bonds.

If such an interaction is present the effect is of shielding whereas if it is absent, the effect is of deshielding.

Electron-donating alkyl groups, for example, lead to increased shielding while electron-withdrawing substituents such as nitro groups lead to deshielding of the nucleus.

In accordance with previously reported peri effects, a significant deshielding of H5 is observed in the major conformers, where this proton is spatially close to H7′.

This ring current leads to a deshielding (downfield shift) of nuclei inside the ring and a shielding (upfield shift) of nuclei outside the ring.

The O atom in EtPO is a Lewis base, and its interaction with Lewis acid sites causes deshielding of the adjacent P atom.

The transition from coil to helix results in pronounced deshielding of the carbonyl and C-α carbons of the polymer and a less dramatic shielding effect on the C-β carbon.

Nucleus Independent Chemical Shift (NICS) analysis is a method of computing the ring shielding (or deshielding) at the center of a ring system to predict aromaticity or antiaromaticity.

In comparison, measurements made with 5-HT-NeuAc showed that all 5-HT protons were slightly deshielded; of the NeuAc protons, slight deshielding of H8 and significant shielding of H3eq, H3ax, and H6 was observed.

Many aromatic and antiaromatic compounds (benzene and cyclobutadiene) are too small to have protons inside of the ring, where shielding and deshielding effects can be more diagnostically useful in determining if a compound is aromatic, antiaromatic, or nonaromatic.

For dipolar couplings, the principal axis corresponds to the internuclear vector between the coupled spins; for the CSA, it corresponds to the direction with the largest deshielding; for the quadrupolar coupling, it corresponds to the z-axis of the electric-field gradient tensor.