Application of frequency domain deconvolution to DQF-COSY spectra for the determination of coupling constants as a tool for signal assignment based on coupling networks

Abstract

Scalar coupling constants can be extracted from the cross peaks of correlation spectra by applying deconvolution to the frequency domain. This requires high resolution in the directly detected dimension. A three‐step automated procedure is presented as a free package running in combination with a major commercial processing software. The initial step allows one to measure coupling constants in an interactive manner in high‐resolution cross‐peak multiplets of weakly coupled spin systems. The user can follow the recursive analysis to assess the reliability of the results. If needed, the course of the automatic procedure can be changed. A second module compiles the data of the cross‐peak analysis and assembles the proton spin network. The algorithm assigns data to a given nucleus if it encounters full consistency of both chemical shifts and coupling constants in all relevant cross peaks. The pairing of signals symmetric with respect to the diagonal defines the connectivity of the spin network. The last module displays the coupling network in a pleasing presentation. Application to androst‐4‐ene‐3, 17‐dione is presented. This example shows that assignment of the coupling network to the molecular structure becomes straightforward. Copyright © 2000 John Wiley & Sons, Ltd.

Combination of Homonuclear Decoupling and Spectral Aliasing to Increase the Resolution in the 1H Dimension of 2D NMR Experiments

“…This approach is in principle possible and would be satisfactory in terms of sensitivity and ability to decouple signals, but two important drawbacks are the time necessary to acquire a series of spectra and (1). [4] The labels α/β refer to hydrogen atoms located below and above the plane of the molecule while e/a distinguish equatorial from axial positions. H in the middle of carbon evolution time t 1 and with composite-pulse decoupling (CPD) applied on the 13 C channel during the direct detection of 1 H. (b) Homonuclear decoupling in F1 can be obtained using a band-selective experiment provided the selected spins are not coupled to each other.…”

“…This compound was selected for its complex homonuclear coupling network [4] (Fig. 2) and the severity of signal overlap.…”

Application of multiplet structure deconvolution to extract scalar coupling constants from 1D nuclear magnetic resonance spectra

“…Following developments in the time domain (Le Parco et al, 1992;Bothner-By and Dadok, 1987;Prost et al, 2006), the frequency domain became more popular to avoid the back-and-forth Fourier transformation. This branch of research started in the 1980s in the group of R. Freeman (del Río Portilla et al, 1994), continued in the 1990s in Geoffrey Bodenhausen's group (Huber and Bodenhausen, 1993a, b;Jeannerat, 2000;Jeannerat and Bodenhausen, 1999) and continued to resonate when the ACCA method (Cobas et al, 2005) was developed for Mestrelab's software Mnova.…”

“…This method was originally developed during the 90s to automatize the analysis of multiplet structure from spectra generated by one of the forgotten pulse sequences: the soft-COSY experiment (Emsley et al, 1990). Multiplet deconvolution proved to be applicable to the more "standard" DQF-COSY experiment (Jeannerat, 2000) after simply increasing the direct acquisition time to provide higher resolution -something which was problematic because of the data storage available at that time but which is no longer justifiable. We shall demonstrate the power of the application of multiplet deconvolution outside the world of 2D correlation spectroscopy, where positive and negative peaks coexist and cause specific challenges (Jeannerat and Bodenhausen, 1999), and apply it to the common -not to say mundanemultiplet structure present in standard 1D NMR spectra.…”

Reconstruction of full high‐resolution HSQC using signal split in aliased spectra

“…4). It is reminiscent of a deconvolution methods used to determine coupling constants [15] except that the split does not have to be measured precisely. Only a distance, out of the set of possible value of N a needs to be determined.…”