Crystals and Aggregates of a Molecular Tetrarotor with Multiple Trityl Embraces Derived from Tetraphenyladamantane

Samples of tetrakis-1,3,5,7-(4′-(3″,3″,3″-triphenylpropynyl)-phenylene)­adamantane and its trityl-deuterated isotopologue were synthesized and their crystallization and packing properties were analyzed within the context of formation of 4- or 6-fold phenyl embraces. The tetrahedral shape of these molecules with four propeller-like triphenylmethyl moieties generates several edge-to-face intermolecular interactions in the solid state that result in the formation of infinite chains of molecules that are tightly interlocked. The formation of analogous edge-to-face intermolecular interactions leading to aggregation in solution was also suggested by NMR experiments carried out in different solvents as a function of concentration. The formation of interdigitated chains was also manifested in fibrils and thin needles, which were documented by scanning electron microscopy (SEM). Single crystal X-ray diffraction studies revealed the presence of multiple 4-fold phenyl embraces and edge-to-face interactions as the leading motifs behind the formation of tightly interlocked molecular chains

Crystals and Aggregates of a Molecular Tetrarotor with Multiple Trityl Embraces Derived from Tetraphenyladamantane

Samples of tetrakis-1,3,5,7-(4′-(3″,3″,3″-triphenylpropynyl)-phenylene)­adamantane and its trityl-deuterated isotopologue were synthesized and their crystallization and packing properties were analyzed within the context of formation of 4- or 6-fold phenyl embraces. The tetrahedral shape of these molecules with four propeller-like triphenylmethyl moieties generates several edge-to-face intermolecular interactions in the solid state that result in the formation of infinite chains of molecules that are tightly interlocked. The formation of analogous edge-to-face intermolecular interactions leading to aggregation in solution was also suggested by NMR experiments carried out in different solvents as a function of concentration. The formation of interdigitated chains was also manifested in fibrils and thin needles, which were documented by scanning electron microscopy (SEM). Single crystal X-ray diffraction studies revealed the presence of multiple 4-fold phenyl embraces and edge-to-face interactions as the leading motifs behind the formation of tightly interlocked molecular chains

Photoinduced and Thermal Denitrogenation of Bulky Triazoline Crystals: Insights into Solid-to-Solid Transformation

The photoinduced and thermal denitrogenation of crystalline triazolines with bulky substituents leads to the quantitative formation of aziridines in clean solid-to-solid reactions despite very large structural changes in the transition from reactant to product. Analysis of the reaction progress by powder X-ray diffraction, solid-state ¹³C CPMAS NMR, solid-state FTIR spectroscopy, and thermal analysis has revealed that solid-to-solid reactions proceed either through metastable phases susceptible to amorphization or by mechanisms that involve a reconstructive phase transition that culminates in the formation of the stable phase of the product. While the key for a solid-to-solid transformation is that the reaction occurs below the eutectic temperature of the reactant and product two-component system, experimental evidence suggests that those reactions will undergo a reconstructive phase transition when they take place above the glass transition temperature