Synthesis and Crystal Structure of a New β-Cyclodextrin Inclusion Complex with Hydrated 2-Thenoyltrifluoroacetone

β-Cyclodextrin (β-CD) inclusion complexes are valuable supramolecular systems because their host–guest arrangements can modulate guest properties and solid-state organization.^1,2 Herein, we report the synthesis and crystallographic characterization of a new β-CD inclusion complex with hydrated 2-thenoyltrifluoroacetone (TTA-H). The complex was prepared by dissolving β-CD (10 mg; 8.8 µmol) in a 1:1 water/ethanol mixture under sonication, followed by addition of TTA (10 mg; 45 µmol), further sonication and controlled agitation at 35 °C. Slow solvent evaporation at 25 °C afforded single crystals suitable for X-ray diffraction after approximately 10 days. Although TTA exists in different forms depending on the solvent, the crystal structure shows that the hydrated form (TTA-H) is preferentially accommodated within the β-CD cavity, with additional water molecules participating in the crystal packing. The supramolecular stabilization is mainly achieved through C–H···O hydrogen bonds. Moreover, TTA-H directly dictated the crystallization mechanism and packing mode.