Further Conventions for NMR Chemical Shifts
IUPAC has published a number of recommendations regarding the reporting of nuclear magnetic resonance (NMR) data, especially chemical shifts. The most recent publication [Pure Appl. Chem. 73, 1795-1818 (2001)] recommended that tetramethylsilane (TMS) serve as a universal reference for reporting the shifts of all nuclides, but it deferred recommendations for several aspects of this subject. This document first examines the extent to which the shielding in TMS itself is subject to change by variation in temperature, concentration, and solvent. On the basis of recently published results, it has been established that the shielding of TMS (along with that of DSS, often used as a reference for aqueous solutions) varies only slightly with temperature but is subject to solvent perturbations of a few tenths of a ppm. Recommendations are given for reporting chemical shifts under most routine experimental conditions and for quantifying effects of temperature and solvent variation, including the use of magnetic susceptibility corrections and of magic-angle spinning (MAS).
This document provides the first IUPAC recommendations for referencing and reporting chemical shifts in solids, based on high-resolution MAS studies. Procedures are given for relating 13C NMR chemical shifts in solids to the scales used for high-resolution studies in the liquid phase. The notation and terminology used for describing chemical shift and shielding tensors in solids is reviewed in some detail, and recommendations are given for best practice.
More news from this company
- Revision of the International System of Units (11/26/2018)
- United Nations proclaim 2019 as the International Year of the Periodic Table of Chemical Elements (01/03/2018)
- IUPAC Announces the Names of the Elements 113, 115, 117, and 118 (12/08/2016)
- Preferred names of constitutional units for use in structure-based names of polymers (06/17/2016)
- Metrological Traceability of Measurement Results in Chemistry: Concepts and Implementation (07/14/2009)