An Interactive NMR Chemical Shift Search Program

Stephen R. Heller
Richard J. Feldmann
National Institutes of Health
Bethesda, Maryland 20014

A computer program has been developed to rapidly search for spectra containing specified chemical shifts from proton nmr spectral data. A number of chemical shift correlation charts have appeared over the years in both the literature and in nmr textbooks (1). One goal of these charts was to enable the student to "get a feeling" and aid in interpretation and structural elucidation of compounds. These charts indicated what chemical group might be giving rise to a peak or group of peaks.

The results of the search program are the Varian catalog numbers since the three digit numbers save computer storage space relative to the length of chemical names (which are not given for many compounds in the file) and the search is designed to be used interactively by the student. It is hoped that the student would sit down at the computer, with catalogs in hand, and interact. The data base used for the search consists of the two Varian spectra catalog (2) which contain proton nmr spectral data on 742 compounds. Only chemical shifts and not coupling constants were used. The chemical shifts had already been assigned in the catalog and it was felt that it would not be possible to extract accurate coupling constants from the spectra in the catalog. About 2800 chemical shifts and their corresponding catalog number references were put into computer readable form. Owing to the variation of chemical shift with temperature, calibration and solvent (to name a few obvious ones) it was felt that a deviation of +0.02 ppm should be included in a search. Therefore the chemical shift of 2.33 ppm will be found in the range of 2.31-2.35 ppm.

The search program accepts chemical shifts in ppm as floating point numbers (with a 0 in front of the decimal point to instill a habit of proper formulation of numeric data). The program cheeks to see if the shift is properly formatted and automatically performs the Boolean logic AND operation on the shifts and determines the number of spectra, if any, that contain the combination of chemical shifts inputted into the program. While the data base is certainly limited, it does contain a large variety of groups and should be of value, in particular, to users with little experience in the interpretation of nmr spectra.

The file generation and file search programs are written in FORTRAN-IV, with the system presently running on a DEC-PDP-10-time sharing computer, and require 13K and 16K of core to run, respectively. Requests for copies of the program should be addressed to Dr. A. W. Pratt, Director, DCRT, NIH, Bethesda, Md. 20014.


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Slomp, G.,and Linberg J. G., Anal. Chem., 39, 69 (1967)
Chamberlain, N. F., Anal. Chew., 40, 1317 (1968)
Emsley, J. W., Feeney, J., and Sutcliffe, L. H., High Resolution Nuclear Magnetic Resonance

Speetroseopy," Pergamon Press, London, 1965. Volumes 1 and 2.
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(2) Bhacca, N. S., Hollis, D. P., JohnsonN, L. E., Pier, E. A., AND Shollery, J. N., "NMR Spectra Catalog," Varian Associates, Palo Alto, 1962 and 1963. Volumes 1 and 2.