New NOAH modules for structure elucidation at natural isotopic abundance

Abstract

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Parallel nuclear magnetic resonance spectroscopy

“…4a). For example, protons directly bound to 13 C can be distinguished from other protons on the basis of their large one-bond C-H coupling using pulse sequence elements such as BIRD pulses 56 , TANGO/BANGO elements 57,58 or zz-filters 59,60 . The development of parallelized nD experiments relies on the concurrent manipulation of multiple magnetization pools such that the respective signals arising from each pool may be detected without the conventional recovery delay [G] (d1 in FIG.…”

“…This can be done even on basic desktop spectrometers equipped with only a single receiver and no gradients (see Supplementary Figure 2). 4d) 20,59,60,[63][64][65] , with each module designed to return other magnetization pools to equilibrium (+z). In these experiments, the FIDs are acquired independently and are initially stored in a file partitioned into multiple memory blocks.…”

“…The gains indicated in Table 3 should therefore be viewed as representative values typical for the characterisation of small organic molecules. 60 or isotopically enriched samples 101,102 .…”

“…In addition to saving time (ρt = 3), this experiment detects more magnetization per unit time offering considerable sensitivity improvements (εt = 1.73). Similarly, a supersequence that combines the PANSY-COSY module (C 2 ) with the NOAH technique BSCC 2 , can record five spectra in a single measurement (H-C HMBC, H-C HSQC, H-H COSY, P-P COSY and P-H COSY) 60 . The C 2 module can easily be appended to many other NOAH…”

“…This not only enables optimal use of instrument time but should also prove to be critical for systems which are reacting or are otherwise unstable since it avoids temporal variations between individual experiments. The direct extraction of a molecular structure from NOAH spectra using CASE routines 96,130 has been successfully demonstrated 59,60 , and is illustrated here for the pharmaceutical zolmitriptan (FIG. 12).…”