The mechanism of the room-temperature synthesis of coordination polymers from ZnO by liquid-assisted grinding (LAG) was investigated, and using catalytic amounts of water allowed us to extend the scope of this synthetic method to copper compounds. The mechanochemical synthesis of model compounds zinc fumarate and copper(II) acetate proceeds through a stepwise mechanism which involves the intermediate formation of solvates with water (in the case of zinc fumarate) or acetic acid (in the case of copper(II) acetate) as kinetic products. The course of zinc fumarate LAG synthesis was explored using three different types of grinding liquids: water, aqueous organic solvents and pure organic solvents. With liquid water, the formation of the kinetic product switches the reaction mechanism from LAG to a neat grinding process. As a result, the reaction scope is limited to either the tetrahydrate or the pentahydrate as the major products. In contrast, the use of aqueous organic solvents as grinding liquids allows the selective synthesis as well as screening for different hydrated and anhydrous forms of zinc fumarate. Different polymorphs of the zinc fumarate coordination polymer can be obtained by changing the organic liquid. As a first step towards the quantitative understanding of how the liquid phase directs LAG mechanosynthesis, we demonstrate that product formation is regulated by the mole fraction and activity of water in the grinding liquid.

This study aimed to synthesize molybdenum complexes coordinated with an aroyl hydrazone-type ligand (H₂L), which was generated through the condensation of 2-hydroxy-5-nitrobenzaldehyde with benzhydrazide. The synthesis yielded two types of mononuclear complexes, specifically [MoO₂(L)(MeOH)] and [MoO₂(L)(H₂O)], as well as a bipyridine-bridged dinuclear complex, [(MoO₂(L))₂(4,4’-bpy)]. Those entities were thoroughly characterized using a suite of analytical techniques, including attenuated total reflectance infrared spectroscopy (IR-ATR), elemental analysis (EA), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction (SCXRD). Additionally, solid-state impedance spectroscopy (SS-IS) was employed to investigate the electrical properties of these complexes. The mononuclear complexes were tested as catalysts in the epoxidation of cyclooctene and the oxidation of linalool. Among these, the water-coordinated mononuclear complex, [MoO₂(L)(H₂O)], demonstrated superior electrical and catalytic properties. A novel contribution of this research lies in establishing a correlation between the electrical properties, structural features, and the catalytic efficiency of the complexes, marking this work as one of the pioneering studies in this area for molybdenum coordination complexes, to the best of our knowledge.

Reactions of copper(II) sulfate with 2,2′-bipyridine (bipy) and amino acids with nonpolar side chains (l-alanine (HAla), l-valine (HVal), or l-phenylalanine (HPhe)) were investigated under different solution-based and mechanochemical methods. Five new ternary coordination compounds were obtained by a solution-based synthesis and three of them additionally by the liquid-assisted mechanochemical method: {[Cu(μ-l-Ala)(H₂O)(bipy)]₂SO₄·2H₂O}_n (1a·2H₂O), {[Cu(μ-l-Ala)(H₂O)(bipy)][Cu(l-Ala)(H₂O)(bipy)]SO₄·2.5H₂O}_n (1b·2.5H₂O), {[Cu(μ-l-Val)(H₂O)(bipy)][Cu(l-Val)(H₂O)(bipy)]₃(SO₄)₂·4H₂O}_n (2·4H₂O), [Cu(l-Phe)(H₂O)(bipy)][Cu(l-Phe)(SO₄)(bipy)]∙8H₂O (3·8H₂O), and [Cu(l-Phe)(H₂O)(bipy)][Cu(l-Phe)(SO₄)(bipy)]∙9H₂O (3·9H₂O). The compounds were characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, and a thermal analysis. Structural studies revealed two structural types, monomeric in 3·8H₂O and 3·9H₂O, polymeric architectures in 1a·2H₂O, and mixed structures (monomeric and polymeric) in 1b·2.5H₂O and 2·4H₂O. The copper(II) ion is either pentacoordinated or hexacoordinated, with an observed Jahn–Teller effect. The crystal structures are based on an intensive network of hydrogen bonds and π interactions. 1a·2H₂O and 2·4H₂O showed substantial in vitro antiproliferative activity toward human hepatocellular carcinoma (HepG2) and moderate activity toward human acute monocytic leukemia cell lines (THP-1).