A family of poly[(m-phenylenevinylene)-co-(p-phenylenevinylene)]s, functionalized in the synthetically accessible C-5 position of the meta-disubstituted phenylene rings have been designed and synthesized:  they are essentially poly{(5-alkoxy-m-phenylenevinylene)-co-[(2,5-dioctyloxy-p-phenylene)vinylene]} (PAmPV) derivatives. A range of these PAmPV polymers have been prepared both (1) by the polymerization of O-substituted 5-hydroxyisophthaldehydes and (2) by chemical modifications carried out on polymers bearing reactive groups at the C-5 positions. PAmPV polymers solubilize SWNT bundles in organic solvents by wrapping themselves around the nanotube bundles. PAmPV derivatives which bear tethers or rings form pseudorotaxanes with rings and threads, respectively. The formation of the polypseudorotaxanes has been investigated in solution by NMR and UV/vis spectroscopies, as well as on silicon oxide wafers in the presence of SWNTs by AFM and surface potential microscopy. Wrapping of these functionalized PAmPV polymers around SWNTs results in the grafting of pseudorotaxanes along the walls of the nanotubes in a periodic fashion. The results hold out the prospect of being able to construct arrays of molecular switches and actuators.

Polymorphic studies of active pharmaceutical ingredients are of great importance for academic researchers as well as pharmaceutical industries, as each polymorph exhibits different physicochemical properties. In this study, vibrational ball milling was used to investigate the polymorphic transformations of sofosbuvir, a drug that is used for the treatment of hepatitis C, under different experimental conditions. We observed that by changing the type of liquid additive, the starting form 1 after 30 min of milling transformed mainly to an amorphous phase or form A, which is the most thermodynamically stable form at room temperature. Furthermore, by exploring different time periods of milling we discovered that, depending on the nature of the liquid additive, the transformation toward the most stable form can occur through different intermediate forms. Additionally, we observed that different amounts of liquid additive can control the time scale of a transformation, allowing a detailed observation of all the stages of the transformations. Finally, via ball milling we had access to several polymorphs of sofosbuvir and we present here for the first time the crystal structures for three of them, forms A, B, and 1.

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