## Sweet J

#### A Desktop Calculator for the Karplus Equation

Calculates the ^{3}J 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 |

### downloads

- Sweet J 2.3
*requires Mac OS 10.5* - source code

### 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.

### links

Empirical parameters for the Karplus equation (hetero- and homonuclear ^{3}J)

A rich collection of special-purposes Karplus equations, with parameters, applications,
plots and primary references.

### 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