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| - Polymorphism, Structure, Guest Conformation, and Dynamics in the Inclusion Compoundof 1,2-Dichloroethane with Tris(5-acetyl-3-thienyl) Methane: a Combined Single Crystaland Powder X-ray Diffraction, 13C CP/MAS, and 2H NMR Study
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| - Various physicochemical characterization techniques were used to study the structure and guest dynamics ofthe 1,2-dichloroethane/tris (5-acetyl-3-thienyl) methane (TATM) inclusion compound. This complex wasobserved to crystallize in two forms, a triclinic P-1 structure and a less usual monoclinic P21/c form. TheX-ray structures indicate that the TATM molecules form “bottleneck” channels parallel to the crystallographicc axis in both forms and that the guests exist exclusively in the trans form. Solid-state deuterium NMRspectroscopy was used to study the dynamics of the 1,2-dichloroethane-d4 guest in the triclinic form. Thesimplest model consistent with the experimental NMR spectra was based on internal rotation about the C−Cbond (a trans/gauche conformational equilibrium). As this was not consistent with the X-ray structure, anothermodel was developed where the trans conformer performs 180° flips about an axis through the center ofsymmetry of the guest and perpendicular to the Cl−C−C−Cl plane. The important point to be taken fromthis work is that complementary methods are often necessary to discriminate between motional models basedon a single technique, and that the simplest model is not necessarily correct.
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