The Derwent Markush Resource (file DWPIM) includes 22 different generic nodes (also called superatoms) which allow for precise Markush structure searches. Even though they are unique to DWPIM, they are seamlessly integrated into the existing STN node hierarchy to enable a single structure (containing STN nodes) to be searched in all structure databases.
Overall, these superatoms represent:
Chemically defined open sets (e.g., Alkyl defines the superatom CHK [Carbon Chains, Carbocycles and Heterocycles])
Chemically defined closed sets (e.g., Alkali and alkaline earth metal defines the superatom AMX [Metals])
Set defined by a property (e.g., Polymer end group defines the superatom PEG [Miscellaneous])
They can be accessed in the structure editor:
Click
the Variables 
icon.
Click
the Derwent (DWPIM/DCR) generic nodes
tab, and then click a category to expand it (in this example,
Heterocycles).
Note: In STNext, the Derwent superatoms are
only applicable to DWPIM and not to DCR. The superatom HAL (halogens)
and MX (metals) are not separately listed since they match to the
corresponding STN nodes X and M, respectively).
For more detailed information on Derwent superatoms, please consult the DWPIM Reference Manual.
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