Exploring Salts of Memantine with Inorganic Anions: From Polymorphism and Solid-State Transitions to Potential for Drug Formulations.

This study examines pharmaceutically acceptable inorganic salts of memantine, specifically focusing on hydrogen sulfate, sulfate, and dihydrogen phosphate salts, with the aim of finding alternatives to the commonly used chloride salt in the treatment of Alzheimer's disease. Through comprehensive solid-state characterization, including powder X-ray diffraction, thermal analysis, and solubility testing, we unveil complex polymorphic behaviors, reversible solid-state transitions, and significant differences in solubility and stability among the salts. Notably, the hydrogen sulfate salt emerges as a promising candidate for drug formulations, offering improved solubility, nonhygroscopic nature, and favorable morphological characteristics compared to the existing chloride salt.

Perhalogenated Anilines as Bifunctional Donors of Hydrogen and Halogen Bonds in Cocrystals with Ditopic Nitrogen-Containing Acceptors.

In this study, we examine the experimental and theoretical capabilities of two perhalogenated anilines, 2,3,5,6-tetrafluoro-4-bromoaniline () and 2,3,5,6-tetrafluoro-4-iodoaniline () as hydrogen and halogen bond donors. A series of 11 cocrystals derived from the two anilines and selected ditopic nitrogen-containing acceptors (4,4'-bipyridine, 1,2-bis(4-pyridyl)ethane, and 1,4-diazabicyclo[2.2.

Molybdenum Complexes Derived from 2-Hydroxy-5-nitrobenzaldehyde and Benzhydrazide as Potential Oxidation Catalysts and Semiconductors.

This study aimed to synthesize molybdenum complexes coordinated with an aroyl hydrazone-type ligand (HL), which was generated through the condensation of 2-hydroxy-5-nitrobenzaldehyde with benzhydrazide. The synthesis yielded two types of mononuclear complexes, specifically [MoO(L)(MeOH)] and [MoO(L)(HO)], as well as a bipyridine-bridged dinuclear complex, [(MoO(L))(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).

Preparative and Catalytic Properties of Mo Mononuclear and Metallosupramolecular Coordination Assemblies Bearing Hydrazonato Ligands.

A series of polynuclear, dinuclear, and mononuclear Mo(VI) complexes were synthesized with the hydrazonato ligands derived from 5-methoxysalicylaldehyde and the corresponding hydrazides (isonicotinic hydrazide (HL), nicotinic hydrazide (HL), 2-aminobenzhydrazide (HL), or 4-aminobenzhydrazide (HL)). The metallosupramolecular compounds obtained from non-coordinating solvents, [MoO(L)] ( and ) and [MoO(L)] ( and ), formed infinite structures and metallacycles, respectively. By blocking two coordination sites with cis-dioxo ligands, the molybdenum centers have three coordination sites occupied by the donor atoms from the rigid hydrazone ligands and one by the N atom of pyridyl or amine-functionalized ligand subcomponents from the neighboring Mo building units.

Direct thermodynamic characterization of solid-state reactions by isothermal calorimetry.

Despite the growing importance of solid-state reactions, their thermodynamic characterization has largely remained unexplored. This is in part due to the lack of methodology for measuring the heat effects related to reactions between solid reactants. We address here this gap and report on the first direct thermodynamic study of chemical reactions between solid reactants by isothermal calorimetry.

The Role of Crystalline Intermediates in Mechanochemical Cyclorhodation Reactions Elucidated by in-Situ X-ray Powder Diffraction and Computation.

The occurrence of crystalline intermediates in mechanochemical reactions might be more widespread than previously assumed. For example, a recent study involving the acetate-assisted C-H activation of N-Heterocycles with [Cp*RhCl ] by ball milling revealed the formation of transient cocrystals between the reagents prior to the C-H activation step. However, such crystalline intermediates were only observed through stepwise intervallic ex-situ analysis, and their exact role in the C-H activation process remained unclear.

Structure-Related Evolution of Magnetic Order in Anisidinium Tetrachlorocuprates(II).

Tetrachlorocuprate(II) hybrids of the three anisidine isomers (-, -, and -, or 2-, 3-, and 4-methoxyaniline, respectively) were prepared and studied in the solid state via X-ray diffraction and magnetization measurements. Depending on the position of the methoxy group of the organic cation, and subsequently, the overall cation geometry, a layered, defective layered, and the structure comprising discrete tetrachlorocuprate(II) units were obtained for the -, -, and -anisidinium hybrids, respectively. In the case of layered and defective layered structures, this affords quasi-2D-layered magnets, demonstrating a complex interplay of strong and weak magnetic interactions that lead to the long-range ferromagnetic (FM) order.

Structural Insights into Layered Tetrahalocuprates(II) Based on Small Unsaturated and Cyclic Primary Ammonium Cations.

Layered hybrid halometallates represent a promising class of multifunctional materials, yet with many open challenges regarding the interaction between building blocks. In this work, we present a synthetic and analytical methodology for the efficient synthesis and structural analysis of a series of novel tetrahalocuprate(II) hybrids based on small alkylammonium cations. Observed robustness in geometrical motifs provided a platform for crystal structure determination, even from the complex laboratory powder diffraction data.

Total Synthesis of Penicyclone A Using a Double Grignard Reaction.

We describe the first total synthesis of penicyclone A, a novel deep-sea fungus-derived polyketide, and a reevaluation of its antimicrobial activity. The synthesis of this unique spirolactone was achieved in 10 steps starting from a known d-ribose derivative. The key steps include a double Grignard reaction for the diastereoselective construction of the chiral tertiary alcohol intermediate, tandem oxidation/cyclization, and photooxygenation, followed by an oxidative rearrangement to introduce the enone functionality.

Magnetoelectric Multiferroicity and Magnetic Anisotropy in Guanidinium Copper(II) Formate Crystal.

Hybrid metal-organic compounds as relatively new and prosperous magnetoelectric multiferroics provide opportunities to improve the polarization, magnetization and magneto-electric coupling at the same time, which usually have some limitations in the common type-I and type-II multiferroics. In this work we investigate the crystal of guanidinium copper (II) formate [C(NH2)3]Cu(HCOO)3 and give novel insights concerning the structure, magnetic, electric and magneto-electric behaviour of this interesting material. Detailed analysis of crystal structure at 100 K is given.

Cobaloximes as Building Blocks in Halogen-Bonded Cocrystals.

In this work, we explore the halogen-bonded cocrystallization potential of cobaloxime complexes in the synthesis of cocrystals with perhalogenated benzenes. We demonstrate a strategy for synthesizing halogen-bonded metal-organic cocrystals by utilizing cobaloximes whose pendant bromide group and oxime oxygen enable halogen bonding. By combining three well-known halogen bond donor molecules differing in binding geometry and composition with three cobaloxime units, we obtained a total of four previously unreported cocrystals.