Synthesis, crystal structure determination and Hirshfeld surface analysis of three new salt forms of creatinine with hydrobromic acid, 3-aminobenzoic acid and 3,5-dinitrobenzoic acid

Creatinine, a biologically important compound, is used to analyze kidney function and kidney diseases in the human body. The salt form of creatinine is used in the formation of drug materials like anti-HIV, antifungal, antiprotozoal, antiviral and antitumour compounds. Here we report the solid-state structures of three new crystalline salts, namely, creatininium (2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium) bromide, C4H8N3O+·Br−, (I), creatininium 3-aminobenzoate, C4H8N3O+·C7H6NO2 −, (II), and creatininium 3,5-dinitrobenzoate, C4H8N3O+·C7H3N2O6 −, (III). These salts have been synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The structural chemistry of salts (I)–(III) and their crystal packing are discussed in detail. The primary interaction between the creatinine cation and the acid anion in the three salts is N—H...Br/O hydrogen bonds. In salt (I), the creatinine cation and bromide anion are connected through a pair of N—H...Br hydrogen bonds forming R 4 2(8) and R 4 2(12) ring motifs. In salts (II) and (III), the creatinine cation interacts with the corresponding anion via a pair of N—H...O hydrogen bonds. The crystal structure is further stabilized by C—H...O and O—H...O hydrogen bonds with the ring motifs R 2 2(8), R 2 1(7) and R 2 1(6). Furthermore, the crystal structures are stabilized by π–π, C—H...π, C—O...π and N—O...π stacking interactions. The contributions made by each hydrogen bond in maintaining the crystal structure stability has been quantified by Hirshfeld surface analysis.

Insight into the Structure and Properties of Novel Imidazole-Based Salts of Salicylic Acid

The preparation of new active pharmaceutical ingredient (API) multicomponent crystal forms, especially co-crystals and salts, is being considered as a reliable strategy to improve API solubility and bioavailability. In this study, three novel imidazole-based salts of the poorly water-soluble salicylic acid (SA) are reported exhibiting a remarkable improvement in solubility and dissolution rate properties. All structures were solved by powder X-ray diffraction. Multiple complementary techniques were used to solve co-crystal/salt ambiguities: density functional theory calculations, Raman and ¹H/¹³C solid-state NMR spectroscopies. In all molecular salts, the crystal packing interactions are based on a common charged assisted ⁺N-H_(SA)⋯O⁻_(co-former) hydrogen bond interaction. The presence of an extra methyl group in different positions of the co-former, induced different supramolecular arrangements, yielding salts with different physicochemical properties. All salts present much higher solubility and dissolution rate than pure SA. The most promising results were obtained for the salts with imidazole and 1-methylimidazole co-formers.

Experimental and Computational Perspectives on Bis(Creatininium) Succinate: An Efficient Organic Nonlinear Optical Material

In this work, combined experimental and computational investigations of a promising organic nonlinear optical (NLO) material, bis(creatininium) succinate (BCS), are reported. The optical quality single crystals of BCS were grown with the dimensions of 12×2×2 mm3. Single crystal X-ray diffraction analysis reveals that BCS crystallized in the orthorhombic system with non-centrosymmetric (NCS) space group F2dd. Vibrational modes of various BCS functional groups were confirmed by using FTIR and FT-Raman spectrum. UV-Vis-NIR spectrum shows that BCS crystal has low near-UV cut-off wavelength at 261 nm and optical transparency window in the visible and near-IR (261–1100 nm) region. Photoconductivity study has been carried out magnificently for grown crystals. The nonlinear optical property such as nonlinear refractive index (n2) and nonlinear absorption coefficient (β) have been investigated by z-scan technique. Density functional theory (DFT) studies were carried out to probe Mulliken charge analysis, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) mapping and first order hyperpolarizability (β) for the optimized molecular structure. Experimental and computed vibrations were correlated well. All these characterization results endorse BCS as a suitable NLO candidate and are discussed in this work.

Creatine: Polymorphs Predicted and Found

Hydrate and anhydrate crystal structure prediction (CSP) of creatine (CTN), a heavily used, badly water soluble, zwitterionic compound, has enabled the finding and characterization of its anhydrate polymorphs, including the thermodynamic room temperature form. Crystal structures of the novel forms were determined by combining laboratory powder X-ray diffraction data and ab initio generated structures. The computational method not only revealed all experimental forms but predicted the correct stability order, which was experimentally confirmed by measurements of the heat of hydration.

Steric inhibition of hydrogen bonding in molecular recognition of dicarboxylic acids: di-topic receptors containing a nitro group designed to behave like monotopic receptors

The ditopic macrocyclic receptors having NO₂ group show inhibition in hydrogen bonding molecular recognition towards the dicarboxylic acids to behave as monotopic receptors.

Hydrogen-bonding patterns in a series of multi-component molecular solids formed by 2,3,5,6-tetramethylpyrazine with selected carboxylic acids

Hydrogen-bonding patterns in a series of cocrystals of 2,3,5,6-tetramethylpyrazine with selected carboxylic acids are discussed.

A new structure of a serotonin salt: comparison and conformational analysis of all known serotonin complexes

Four serotonin salt structures (serotonin adipate, C10H13N2O(+)·C6H9O4(-), is a previously unknown structure) were analysed to understand the influence of the anion on serotonin conformation. Hydrogen bonding alone favours a flat conformation, whereas additional stacking interactions between ions may possibly account for the nonplanar conformation. Since molecular conformation, stability and biological activity are interrelated, one can consider influencing the chemical and biological properties of serotonin by selecting an appropriate counter-ion for salt formation.