The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

The mechanochemical preparation of silver sulfadiazine and dantrolene, two marketed active pharmaceutical ingredients, was investigated by in situ Raman spectroscopy. For the first time, the mechanochemical transformations involving highly fluorescent compounds could be studied in situ with a high-resolution Raman system combined with a unique suitable Raman probe. Moreover, the kinetic features of the mechanochemical process were examined by a mathematical model allowing to describe the chemical changes under mechanical stress. This approach is promising both to broaden the scope of Raman in situ investigations that would otherwise be impossible and for process optimization at any scale.

The light-induced phase transition of TiO2\ud nanoparticles from anatase to rutile structure is reported\ud depending on the surrounding environment, the transition\ud being accomplished under oxygen-poor conditions. The\ud transition mechanism is interpreted in the framework of oxygen\ud adsorption and desorption phenomena with the involvement of\ud surface oxygen vacancies and F centers. It is shown that the\ud observed phase transition is not thermally driven because the\ud local temperature of the nanoparticles during irradiation is\ud about 370 K (estimated through the Stokes to anti-Stokes\ud Raman peaks ratio). On the contrary, the phase transition is\ud initiated by intragap irradiation (with the exception of the red\ud light one) that acts as TiO2 surface sensitizer, promoting the\ud activation of the surface and the nucleation of rutile crystallites starting from two activated anatase neighboring nanoparticles

The gram-scale mechanochemical preparation of marketed drugs Nitrofurantoin and Dantrolene is herein reported.