Generalized indirect covariance

Key Words 1,1-ADEQUATE, 1,/i-ADEQUATE, /%1-ADEQUATE, /i,/77-ADEQUATE, Structure elucidation, Unsymmetrical indirect covariance, Generalized indirect covariance, Carbon-carbon correlation. 

Finally, retrorsine, 22, has also recently been used as a model compound for a study by the author and co-workers that investigated the 1,1- and 1,h-ADEQUATE spectra of the molecule in conjunction with unsymmetrical and generalized indirect covariance processing to afford the corresponding HSQC-1,1-ADEQUATE and HSQC-1,h-ADEQUATE spectra, respectively.51... 

Unsymmetrical indirect covariance and generalized indirect covariance processing using ADEQUATE data... 

As can be seen, UIC according to Eq. (5.22) does not lead to a symmetric matrix, unless F and G are themselves symmetric. Therefore, the square root operation must not be applied. It has been discussed that the lack of this operation causes a more significant presence of artefacts from the mathematical operations. As a remedy, generalized indirect covariance (GIG) according to Eq. (5.23) was proposed [14]. 

Spectrus ACD/Labs Data format independent direct, indirect, unsymmetrical and generalized indirect covariance processing http //WWW. acdlabs.com/ products/ spectrus/... 

D.A. Snyder, R. Bruschweiler, Generalized indirect covariance NMR formalism for establishment of multidimensional spin correlations, J. Phys. Chem. A 113 (2009) 12898. 

G.E. Martin, W.R. Thomas, K.A. Blinov, C.G. Ankhn, W. Bermel, HMBC-1,1-ADEQUATE via generalized indirect covariance a high sensitivity alternative to n,l-ADEQUATE, Magn. Reson. Chem. 50 (2012) 691. 

G.E. Martin, Posaconazole application of HSQC-ADEQUATE from general indirect covariance processing, J. Heterocyclic Chem. 49 (2012) 716. 

Another approach to the presentation of chemical shift data is provided by the utilization of unsymmetrical [35] or generalized indirect covariance [36] processing of a HSQC spectrum with long-range... 

Doubly indirect covariance (DIG) yields a symmetric correlation map [13]. It can further be considered as a bridge to the generalization of indirect covariance. It implies that correlation spectra, that are used for indirect covariance, themselves may be a creation of a previous covariance transformation. Scheme 5.1 serves as an example to elucidate this perspective. In Scheme 5.1A and B, indirect covariance generates homonuclear spectra. Part (C) leads to the creation of a heteronuclear correlation, which itself can be taken as component spectrum for transformation (A) or (B). It is apparent that Scheme 5.1 represents an oversimplification of the types of indirect covariance treatment. A wider variety of spectra that can be obtained by UIC processing is collected in Table 5.1. 

The two large-scale cormnercial vendors of spectrometer-independent NMR software currently offer covariance processing as a feature of their spectral manipulation and interpretation suites. The Spectrus platform by ADC/Labs and the MNova by Mestrelab Research provide stand-alone solutions that allow the import of all spectrometer data formats without the necessity of pre-processing. Covariance processing can be performed according to the direct, indirect, and generalized indirect formalism. The doubly indirect covariance transformation is formd in MNova. While... 

Covariance Toolbox David Snyder MATLAB/GNU OCTAVE base NMRPipe data format direct, indirect, 4D, generalized indirect and Z-matrix processing [57] http //WWW. mathworks. com/ matlabcentral/ fileexchange/ 27264- covariance-nmr- toolbox... 

While the use of direct, indirect and unsymmetrical and generalized covariance is well represented in the literature, the exploitation of heterospectroscopy with NMR as one element is stiU scarce. StiU, covariance analysis as dealt with here is a processing scheme that is open to application. It cannot be excluded therefore that some of the methods are employed without disclosure to a general audience. In this respect, the mathematical or data conversion tools for covariance treatment are readily available today. 

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