Physicochemical Characterization of Tris(5-acetyl-3-thienyl)methane Inclusion Compounds with 1,n-Dichloroalkane Guests (n = 1 to 10). A Combined TGA, ~(13)C CP/MAS NMR, Powder X-ray Diffraction and DSC Study

摘要

Various physicochemical characterization techniques were used to study tris(5-acetyl-3-thienyl)methane (TATM) inclusion compounds with 1,n-dichloroalkane guests (n = 1 - 10). Thermogravimetric analysis (TGA) experiments allowed us to determine host-guest stoichiometric ratios. We determined that the smallest size guests (n = 1 - 4) form 2H:1G TATM inclusion compounds, the intermediate size guests (n = 5 and 6) form 3H:1G TATM inclusion compounds, while the largest size guests (n = 8 - 10) form 4H:1G TATM inclusion compounds. From the multiplicity of the host signals in the ~(13)C CP/MAS NMR spectrum, we were able to determine the number of host molecules in the asymmetric unit of each inclusion compound. For n = 1 - 4, there is 1 TATM molecule in the asymmetric unit, for n = 5 and 6, there are 3 TATM molecules in the asymmetric unit, while for n = 8 - 10, there are 2 TATM molecules in the asymmetric unit. Powder X-ray diffraction experiments were conducted to determine if any of the nine guests form isostructural TATM inclusion compounds. Only 1,9-dichlorononane and 1,10-dichlorodecane form isostructural TATM inclusion compounds. This behaviour is compared with isostructuralism among previously studied TATM-alkyl halide guest systems. DSC experiments were performed to determine the relationship between the size of guest and the thermal properties of the inclusion compound. We found a direct relationship between the melting temperature and the heat of fusion. These data are compared to a recent study on urea-carboxylic acid complexes.