The Lisbon Supramolecular Green Story: Mechanochemistry towards New Forms of Pharmaceuticals

Multicomponent Amorphous Solid Forms of Telmisartan: Insights into Mechanochemical Activation and Physicochemical Attributes

The present work aims to explore the new solid forms of telmisartan (TEL) with alpha-ketoglutaric acid (KGA) and glutamic acid (GA) as potential coformers using mechanochemical approach and their role in augmentation in physicochemical parameters over pure crystalline TEL. Mechanochemical synthesis was performed using 1:1 stoichiometric ratio of TEL and the selected coformers in the presence of catalytic amount of ethanol for 1 h. The ground product was characterized by PXRD, DSC, and FTIR. The new solid forms were evaluated for apparent solubility, intrinsic dissolution, and physical stability. Preliminary characterization revealed the amorphization of the mechanochemical product as an alternate outcome of cocrystallization screening. Mechanistic understanding of the amorphous phase highlights the formation of amorphous-mediated cocrystallization that involves three steps, viz., molecular recognition, intermediate amorphous phase, and product nucleation. The solubility curves of both multicomponent amorphous solid forms (TEL-KGA and TEL-GA) showed the spring-parachute effect and revealed significant augmentation in apparent solubility (8-10-folds), and intrinsic dissolution release (6-9-folds) as compared to the pure drug. Besides, surface anisotropy and differential elemental distributions in intrinsic dissolution compacts of both solid forms were confirmed by FESEM and EDX mapping. Therefore, amorphous phases prepared from mechanochemical synthesis can serve as a potential solid form for the investigation of a cocrystal through amorphous-mediated cocrystallization. This has greater implications in solubility kinetics wherein the rapid precipitation of the amorphous phase can be prevented by the metastable cocrystal phase and contribute to the significant augmentation in the physicochemical parameters.

Mechanochemical Phosphorylation of Acetylides Using Condensed Phosphates: A Sustainable Route to Alkynyl Phosphonates

In pursuit of a more sustainable route to phosphorus-carbon (P-C) bond-containing chemicals, we herein report that phosphonates can be prepared by mechanochemical phosphorylation of acetylides using polyphosphates in a single step, redox-neutral process, bypassing white phosphorus (P4) and other high-energy, environmentally hazardous intermediates. Using sodium triphosphate (Na5P3O10) and acetylides, alkynyl phosphonates 1 can be isolated in yields of up to 32%, while reaction of sodium pyrophosphate (Na4P2O7) and sodium carbide (Na2C2) engendered, in an optimized yield of 63%, ethynyl phosphonate 2, an easily isolable compound that can be readily converted to useful organophosphorus chemicals. Highly condensed phosphates like Graham's salt and bioproduced polyphosphate were also found to be compatible after reducing the chain length by grinding with orthophosphate. These results demonstrate the possibility of accessing organophosphorus chemicals directly from condensed phosphates and may offer an opportunity to move toward a "greener" phosphorus industry.

Mechanochemistry in Portugal-A Step towards Sustainable Chemical Synthesis

In Portugal, publications with mechanochemical methods date back to 2009, with the report on mechanochemical strategies for the synthesis of metallopharmaceuticals. Since then, mechanochemical applications have grown in Portugal, spanning several fields, mainly crystal engineering and supramolecular chemistry, catalysis, and organic and inorganic chemistry. The area with the most increased development is the synthesis of multicomponent crystal forms, with several groups synthesizing solvates, salts, and cocrystals in which the main objective was to improve physical properties of the active pharmaceutical ingredients. Recently, non-crystalline materials, such as ionic liquids and amorphous solid dispersions, have also been studied using mechanochemical methods. An area that is in expansion is the use of mechanochemical synthesis of bioinspired metal-organic frameworks with an emphasis in antibiotic coordination frameworks. The use of mechanochemistry for catalysis and organic and inorganic synthesis has also grown due to the synthetic advantages, ease of synthesis, scalability, sustainability, and, in the majority of cases, the superior properties of the synthesized materials. It can be easily concluded that mechanochemistry is expanding in Portugal in diverse research areas.