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enter image description here

Let's say I have a compound shown above (SMILES: CCC(F)(F)F), and I want to exclude the trifluoromethyl group with SMARTS, how would I do that? I have tried [CX4;!$(C(F)(F)F)] but it does not exclude C(F)(F)F according to RDKit:

molecule = Chem.MolFromSmiles('CCC(F)(F)F')
pattern = Chem.MolFromSmarts('[CX4;!$(C(F)(F)F)]')
molecule.HasSubstructMatch(pattern) --> expected False, but returns True

I think the recursive portion is written incorrectly but I'm not sure how to correct it.

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    $\begingroup$ In your code, the SMARTS reads [CX4;!$(C(F)(F)F)] with ; not & I don't have time to investigate, but SMARTS viewer is usually helpful for these: smarts.plus $\endgroup$
    – Geoff Hutchison
    Apr 29, 2021 at 19:36
  • $\begingroup$ @GeoffHutchison Ah sorry, I corrected it to avoid confusion. I actually tried several variations of the SMARTS patterns and none of them worked. Based on the SMARTS viewer [CX4;!$(C(F)(F)F)] looks correct, but clearly I'm missing something $\endgroup$
    – Theophylline
    Apr 29, 2021 at 21:09
  • $\begingroup$ I believe a duplicate here: chemistry.stackexchange.com/questions/150737/… $\endgroup$
    – S R Maiti
    May 1, 2021 at 11:14

1 Answer 1

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Your SMARTS works.

To see what a SMARTS finds, it is always a good idea to depict the result.

from rdkit import Chem
from rdkit.Chem.Draw import IPythonConsole

patt = Chem.MolFromSmarts('[CX4;!$(C(F)(F)F)]')

m = Chem.MolFromSmiles('CCC(F)(F)F')

m.GetSubstructMatches(patt)
m

notrifluor

The SMARTS should find all Carbons with 4 connections (implicit Hydrogen count), but not (C(F)(F)F). That is why HasSubstructMatch returns True.

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