Bond anisotropy shifts

H9 by 0.11 ppm with respect to values in 5. These cyclopropane ring-induced shifts were accounted for in a reasonable manner using bond anisotropy values indeed the data were less well rationalized when a ring current in the cyclopropane ring was invoked. 

In summary, the phenomenon of chemical shift enables the chemist to obtain some fundamental information about electronegativities, bond anisotropies, and so on. Above all, the ability to observe the chemical shift causes hydrogen atoms (and to some extent other nuclei) to become functional groups that can be qualitatively and quantitatively estimated. 

Tjandra N and Bax A 1997 Solution NMR measurement of amide proton chemical shift anisotropy in N-15-enriched proteins. Correlation with hydrogen bond length J. Am. Chem. Soc. 119 8076-82... 

Note that the lack of rotation about the double bond means that E and Z isomers are distinct entities in the same way that cis and trans isomers are distinct in conventional alkenes. It is not really feasible to give a comprehensive guide to the chemical shifts of these protons but expect them to be somewhat lower field (approx. 1 ppm) than for comparable alkenes, with chemical shifts being driven largely by the anisotropy of the substituents. 

The chromophore environment can affect the spectral position of the absorption and emission bands, the absorption and emission intensity (eM, r), and the fluorescence lifetime as well as the emission anisotropy, e.g., in the case of rigid matrices or hydrogen bonding. Changes in temperature typically result only in small spectral shifts, yet in considerable changes in the fluorescence quantum yield and lifetime. This sensitivity can be favorably exploited for the design of fluorescent sensors and probes [24, 51], though it can unfortunately also hamper quantification from simple measurements of fluorescence intensity [116], The latter can be, e.g., circumvented by ratiometric measurements [24, 115],... 

The hydrogen bond length in Watson-Crick base pairs can be characterized using the recently developed method of measuring the cross-correlated relaxation [61] between H chemical shift anisotropy and dipole-dipole coupling of H and its hydrogen bond donor... 

The characterisation of the angular dependence of the interaction of two dipole tensors A1 A2 and B B2 is therefore straightforward, namely it depends on the projection angle of the two bonds between A1 and A2 and between B1 and B2. The orientation and magnitude of the chemical shift anisotropy (CSA) tensor, which also can cause cross-correlated relaxation, is not know a priori and therefore needs to be determined experimentally or... 

Clore et al. [63] have noticed that for an isotropic distribution of dipolar bond-vectors the probabilities resemble the shape of a chemical shift anisotropy powder pattern... 

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