9‑Trifluoromethylxanthenediols: Synthesis and Supramolecular Motifs

The synthesis of
four derivatives and the single-crystal X-ray
structures of six 9-trifluoromethylxanthenediols (TFXdiols) I–VI are analyzed in this work. These
compounds were obtained through superacid-catalyzed condensation of
dihydroxybenzenes with 1,1,1-trifluoroacetone or 2,2,2-trifluoroacetophenone.
The title molecules have a convex molecular structure due to their
three fused rings of the xanthene moiety. We have found that, similar
to resorcinol, the configuration of the hydroxyl groups is of great
relevance for the crystal packing favoring either interactions above
and below their molecular plane or lateral interactions that create
layers. Considering that reports of TFXdiols are very scarce, our
findings contribute to a better understanding of the molecular conformation
and intermolecular interactions in their crystal structures. A similar
analysis was extended to a fortuitous cocrystal obtained between 9-trifluoromethyl-9-(4′-fluorophenyl)-xanthenediol
and 1,4-dihydroxybenzene, showing that these structures might be used
to obtain cocrystals in the future.