Open Access

This study investigates the mechanochemical reactions between AgBr 3-picolylamine and 4-picolylamine. The use of different stoichiometry ratios of the reagents allows [(AgBr)(n-pica)]n and [(AgBr)2(n-pica)]n to be obtained, and we report the new structures of [(AgBr)2(3-pica)]n and [(AgBr)2(4-pica)]n which are characterized by the presence of the following: (a) infinite inorganic chains, (b) silver atom coordinated only by bromide atoms and (c) argentophilic interactions. Furthermore, we studied the interconversion of [(AgBr)(n-pica)]n/[(AgBr)2(n-pica)]n by mechanochemical and thermal properties. The in situ experiments suggest that [(AgBr)(3-pica)]n is kinetically favoured while [(AgBr)2(3-pica)]n is converted into [(AgBr)(3-pica)]n only with a high excess of the ligand. Finally, the liquid nature of the ligands is not sufficient to assist the grinding process, and the complete reaction is observed with the addition of a small quantity of acetonitrile.

Kinetics information on the progress of the mechanochemical reactions is key to their understanding and subsequent scale-up. For crystalline materials, the most robust and tested method for obtaining kinetic data is the Quantitative Phase Analysis (QPA) via Rietveld refinement. In this work, we tested the feasibility of the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method on powder X-ray diffraction (PXRD) data of mechanochemical processes by studying the system theophylline (TP) and malonic acid (MA) in a 1 : 1 stoichiometric ratio at different milling conditions. We have highlighted the strengths and weaknesses of the MCR-ALS method, and we demonstrated why it may be an alternative route to obtain quantitative information on mechanochemical kinetics.

Rifaximin solvates, obtained via cocrystallization with five glycols and four glycol ethers, display six distinct packing types (PT-I−VI), as revealed by single-crystal and powder X-ray diffraction (PXRD). Five of these packing types are unprecedented, extending the structural landscape of rifaximin well beyond the hydrated forms known to date. While the canonical rifaximin dimer, stabilized by amide···amide and water-mediated hydrogen bonds, predominates, alternative arrangements arise when solvent molecules participate in hydrogen bonding. The glycol or glycol ether stoichiometry, together with the preparation method of choice (grinding, slurry, solution), governs the crystallization outcome: low solvent content yields PT-II, whereas higher amounts favor PT-I, anhydrous PT-III, or, in specific cases, unique architectures (PT-IV, V, and VI). These findings highlight the balance between intrinsic supramolecular preferences and structural adaptability to solvent inclusion, providing a rational basis for the design of novel solvated forms.

Mechanochemical Innovations for Sustainable Synthesis of Framework Materials and Industrial ScaleUp Mechanochemistry has emerged as a powerful approach for sustainable materials synthesis and processing, with significant potential to meet the UN Sustainable Development Goals. This presentation will highlight our recent advancements in understanding, monitoring, and scaling-up mechanochemical synthesis of framework materials, focusing on the balance between fundamental understanding of reaction mechanisms and its practical applications in energy storage and energy transfer materials. A central focus of our work has been the development and application of time-resolved in situ monitoring techniques for mechanochemical processes. Our research on real-time synchrotron X-ray diffraction has enabled unprecedented insights into reaction pathways and kinetics. Recently, we have successfully applied energy-dispersive X-ray diffraction for time-resolved in situ monitoring of reactive extrusion, marking a significant step towards ‘lighting up’ industrial-scale mechanochemistry. Bridging fundamental understanding with practical applications, we have explored the mechanochemical synthesis of functional materials for energy storage and transfer, making process in the mechanochemical synthesis of highly proton-conductive metal phosphonates, demonstrating the potential of mechanochemistry to manufacture advanced materials for energy applications.

Integrating real-time monitoring with precise temperature control and mechanochemical processing represents a transformative approach to the controlled engineering of polymorphic forms in molecu-lar solids. Combining these methodologies overcomes the limitations of traditional solution-based or purely thermal approaches, enabling access to metastable or otherwise elusive polymorphs under milder and more sustainable conditions. Recent studies have shown that mechanochemical trans-formations proceed through distinct kinetic stages, including prolonged induction periods that can be tuned by adjusting the mechanical energy input[1]. These induction periods are associated with pro-cesses of mechanical activation, such as the accumulation of defects and increased surface energy, which lower the effective energy barriers for polymorphic transitions. Crucially, it is the total accumu-lated mechanical energy, rather than the duration or intensity of milling alone, that dictates the onset of polymorphic conversion, offering a new dimension of kinetic control[2-5]. Variable temperature ball milling reveals that the temperature required to induce polymorphic trans-formations can be significantly lower than under conventional thermal methods. For instance, tran-sitions that typically require high temperatures under equilibrium conditions can be achieved at sub-stantially lower temperatures in the presence of mechanical activation. This has been demonstrated in cocrystal systems such as nicotinamide-pimelic acid and isonicotinamide-glutaric acid, where the transition temperature was lowered by up to 25°C[2,3]. Real-time, in situ powder X-ray diffraction and temperature monitoring are essential for capturing transient phases and elucidating the interplay between thermal and mechanical effects. This confirms that combining mechanical energy with con-trolled temperature not only accelerates transformation kinetics, but also expands the accessible polymorphic landscape [2,3]. Collectively, these advances underscore the potential of real-time monitored, temperature-controlled mechanochemistry as a robust platform for the selective design and manufacturing of polymorphs. This approach provides unprecedented control over solid-state reactivity and opens new avenues for the sustainable and targeted engineering of functional materials and pharmaceuticals.