Ultrasound-assisted construction of halogen-bonded nanosized cocrystals that exhibit thermosensitive luminescence.

Multi-component organic nanocrystals that are comprised of two or more supramolecular building blocks can be used to extend the design and assembly scope of solid molecular materials. Herein, we report the use of ultrasonication to prepare halogen-bonded stilbene-based nano-cocrystals that exhibit different photoemission properties, including one- and two-phonon emission and fluorescence lifetimes, relative to those of macrodimensional crystals. The structural transformation from nano-cocrystals into nanocrystals upon heating results in a luminescence red-shift from greenish blue to yellow. The temperature-dependent ratiometric luminescence may allow such nano-cocrystals to be used as fluorescent sensors and thermosensitive materials.

Real-time in situ powder X-ray diffraction monitoring of mechanochemical synthesis of pharmaceutical cocrystals.

Looking in: The penetrating power of high-energy X-rays provides a means to monitor in situ and in real time the course of ball-milling reactions of organic pharmaceutical solids by detecting crystalline phases and assessing the evolution of their particle sizes. Upon switching from neat grinding to liquid-assisted grinding, cocrystal formation is enabled or tremendously accelerated, while the reaction mechanism alters its course.