Clathrate engineering of Piedfort hosts. Crystal structures and molecular modeling of the para-mono- and meta-di-methyl/t-butyl substituted derivatives of 2,4,6-tris(alkylphenoxy)-1,3,5-triazine

X-ray crystal structure analyses of four related 2,4,6-tris-(alkylphenoxy)- 1,3,5-triazine host candidates were planned to clarify conditions of the Pi edfort pair based inclusion formation. The 3,5-di-t-butylphenoxy substitute d compound yields inclusion and exhibits dimorphism as well. Contrasting th e inclusion, no Piedfort pairing was observed in the dimorphs. Other para- and meta-t-butyl/methyl substituted molecules did not give clathrates. Homo molecular columns of polymeric Piedfort stacks were formed instead. The sta cking distances between triazine rings in the polymeric columns vary smooth ly with the size and position of the substituents. We conclude that bulky s ubstituents must impede parallel to the expected direction of favorable Pie dfort stacking to form inclusion supramolecules.