Before you start

Molecular descriptors can be calculated for any connected molecular structure; however, the complete set of molecular descriptors can be calculated only for those molecules containing the chemical elements, for which all physico-chemical properties used as the weighting schemes are available. See the list of weighting schemes for more details.


If a molecule contains chemical elements for which some property is undefined, then it will be processed anyway, but a limited set of molecular descriptors will be provided.


Dragon cannot deal with salts.


The structure files cannot be generated in Dragon; they require to be created before using Dragon by specific chemical drawing programs.


To make full use of Dragon utilities, 3D optimised structures with hydrogens are required.


Note that Dragon does not perform geometry optimisation, nor transform topological structures into the corresponding 3D geometrical structures.


In the case of molecular structures lacking in hydrogen atoms, the software can attach hydrogens to atoms in order to make up the rest of their normal valence. However, as atomic spatial coordinates are not provided, calculations are restricted to 0D, 1D and 2D descriptors.


Regardless of the way a molecular structure has been defined in the input file, it will always be converted into an internal standard representation by Dragon rules for bond order and aromaticity detection.