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Sweet J

A Desktop Calculator for the Karplus Equation

Calculates the 3J coupling constant from the dihedral angle and the electronegativity of the substituents using either the Altona equation or a generalized Karplus equation.

Latest version:2.4
date:January 5, 2022
what's new:recompiled for Apple Silicon; interface compatible with Mac OS 12



special notes

When the residues on the same center are identical but their labels are different, Sweet J treats that center as chiral. The two residues are given an highest CIP priorities than the remaining substituents, whilst their relative priority is given by the alphabetical order (case-sensitive) of the labels.


Empirical parameters for the Karplus equation (hetero- and homonuclear 3J)
A rich collection of special-purposes Karplus equations, with parameters, applications, plots and primary references.


Giuseppe Balacco
A Desktop Calculator for the Karplus Equation
J. Chem. Inf. Comput. Sci., 1996, 36 (4), pp 885–887
DOI: 10.1021/ci950227r

C.A.G. Haasnoot, F.A.A.M. DeLeeuw and C. Altona
The relationship between proton-proton NMR coupling constants and substituent electronegativities-I: An empirical generalization of the Karplus equation
Tetrahedron, 1980, 36, pp 2783-2792
DOI: 10.1016/0040-4020(80)80155-4

Martin Karplus
Vicinal Proton Coupling in Nuclear Magnetic Resonance
J. Am. Chem. Soc., 1963, 85 (18), pp 2870–2871
DOI: 10.1021/ja00901a059

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