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ChemOffice.Com - CambridgeSoft

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• Mol- or SDFiles obtained from ISIS or other<br />

programs do not know about this tag, and thus<br />

cannot convey thick bonds. However, such<br />

files may be edited by hand to include the<br />

ChemFinder tag.<br />

• An MDL file written by ChemFinder,<br />

containing tags, should in principle be readable<br />

by any program which can import such a file.<br />

The unrecognized tags should simply be<br />

ignored.<br />

Normalization<br />

Closed rings of alternating single and double bonds<br />

match their alternative resonance forms if aromatic<br />

by the Hückel 4n+2 rule.<br />

With a full structure search and the Match<br />

Double Bond stereo option selected, the query:<br />

finds any of:<br />

OH<br />

does NOT find any of:<br />

Atom Properties<br />

ChemFinder allows special atom properties to be<br />

assigned to an atom in a query. These properties are<br />

usually only meaningful during a search. They<br />

generally serve to broaden or narrow the scope of<br />

the search.<br />

Special Atom Types<br />

ChemFinder recognizes six special atom types that<br />

can match any one of a predefined set of elements:<br />

• Amatches any non-hydrogen atom.<br />

• Qmatches any heteroatom (non-hydrogen,<br />

non-carbon).<br />

• Rmatches any atom, including hydrogen.<br />

• Xmatches any halogen (F, Cl, Br, I, At).<br />

• LNmatches a link node (placeholder for<br />

unspecified atoms). See “Searching Link<br />

Nodes and Multivalent Rs (MVRs)” on page<br />

339 for details.<br />

• Mmatches any metal atom, shaded in the<br />

periodic table below:<br />

OH<br />

OH<br />

OH<br />

OH<br />

H<br />

O<br />

H<br />

O<br />

Atom Lists<br />

As with the predefined special atom types, an atom<br />

list is a list of atoms, one of which must match the<br />

target atom.<br />

For example:<br />

[Cl,Ag,N] atom must be Cl or Ag or N<br />

Appendices<br />

<strong>ChemOffice</strong> 2005/Appendix Structural Query Features • 681<br />

Atom Properties

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