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A novel crystal, the mono-protonated metformin acetate (1), was obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. It was found that one of the imino group in the metformin cation was protonated along with the proton transfer from the secondary amino group to the other imino group. Its crystal structure was then compared with the previously reported diprotonated metformin oxalate (2). The difference between them is that the mono-protonated metformin cations can be linked by hydrogen bonding to form dimers while the diprotonated metformin cations cannot. Both of them are stabilized by intermolecular hydrogen bonds to assemble a 3-D supermolecular structure. The four potential tautomer of the monoprotonated metformin cation (tautomers 1a, 1b, 1c and 1d) were optimized and their single point energies were calculated by Density Functional Theory (DFT) B3LYP method based on the Polarized Continuum Model (PCM) in water, which shows that the most likely existed tautomer in human cells is the same in the crystal structure. Based on the optimized structure, their Wiberg bond orders, Natural Population Analysis (NPA) atomic charges, molecular electrostatic potential (MEP) maps were calculated to analyze their electronic structures, which were then compared with the corresponding values of the diprotonated metformin cation (cation 2) and the neutral metformin (compound 3). Finally, the possible tautomeric mechanism of the monoprotonated metformin cation was discussed based on the observed phenomena. [ABSTRACT FROM AUTHOR]

In the title compound, [Er(IN)3(H2O)2] n, where IN is the isonicotinate anion, C6H4NO2−, the asymmetric unit contains one half-mol­ecule. The ErIII atom lies on a crystallographic twofold axis and is coordinated by four and two carboxyl­ate O atoms from bridging and chelating isonicotinate groups, respectively, and by two O atoms from water mol­ecules, yielding an eight-coordinate square-anti­prismatic geometry. In the crystal structure, the polymer features an infinite doubly carboxyl­ate-bridged chain-like structure with one chelating carboxyl­ate group on each metal centre. Adjacent chains are, in turn, connected to each other through inter­molecular O—H⋯O and O—H⋯N hydrogen bonds, forming a three-dimensional network. [ABSTRACT FROM AUTHOR]

The title compound, C18H17N3O2·CH4O, is a Schiff base compound, which is derived from the condensation of equimolar amounts of 4-amino­antipyrine and 4-hydroxy­benzaldehyde. In the crystal structure, the MeOH molecules are linked to the Schiff base molecules through intermolecular O—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, [Zn(C13H11N2O)(H2O)](NO3)·H2O, the Zn atom is coordin­ated by two N atoms and one O atom from the Schiff base ligand, and another O atom from a water mol­ecule. The four atoms around the metal constitute a slightly distorted square-planar geometry. The O atoms in both the ions and water mol­ecules contribute to O—H⋯O hydrogen bonds, leading to the formation of sheets parallel to the ac and bc planes. [ABSTRACT FROM AUTHOR]

The title compound, C20H17NO6, was synthesized by the reaction of syringaldehyde with hippuric acid. The molecule adopts a Z configuration about the central olefinic bond. The two benzene rings and the oxazolone ring are almost coplanar. The crystal structure is stabilized by weak intermolecular C—H...O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the title compound, C15H15N3O4·H2O, the organic molecule exists in the keto–imine tautomeric form. The benzene ring makes a dihedral angle of 49.9 (2)° with the pyridine ring. The molecules pack in a three-dimensional framework structure by a combination of O—H...O, O—H...N, N—H...O and N—H...N hydrogen bonds. The water molecule of hydration is disordered [ratio of components 0.758 (7):0.242 (7)]. [ABSTRACT FROM AUTHOR]

In the title compound, C24H18F3N3O, the molecule exists in the enamine–keto tautomeric form. The pyrazolone ring makes dihedral angles of 31.8 (2), 45.4 (2) and 71.2 (2)° with the 1-phenyl, aniline and methylene-bound phenyl rings, respectively. An intramolecular N—H...O hydrogen bond helps to stabilize the molecular conformation. [ABSTRACT FROM AUTHOR]

In the title compound, C21H26N2O3, the molecule adopts an E configuration about the central C=N double bond and exists in the phenol–imine tautomeric form. The two benzene rings make a dihedral angle of 38.5 (4)°. Intramolecular O—H...N hydrogen bonding is present. [ABSTRACT FROM AUTHOR]

In the title compound, C16H24N3O10PS2, the thiazolidine ring is approximately planar and the tetrahydropyran ring adopts a chair conformation. The crystal packing is stabilized by intermolecular N—H...O, C—H...S and C—H...O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the title compound, C19H19N3O2, the 2-methoxy­phenyl ring is almost coplanar with the pyrazoline ring [dihedral angle 8.7 (4)°], while the phenyl ring forms a dihedral angle of 54.9 (2)° with the pyrazoline ring. [ABSTRACT FROM AUTHOR]

In methylaminium 4',7-dihydroxyisoflavone-3'-sulfonate di- hydrate, CH6N+·C15H9O7S-·2H2O, 11 hydrogen bonds exist between the methylaminium cations, the isoflavone-3'-sulfonate anions and the solvent water molecules. In hexaaquairon(II) bis(4',7-diethoxyisoflavone-3'-sulfonate) tetra- hydrate, [Fe(H2O)6](C19H17O7S)2·4H2O, 12 hydrogen bonds exist between the centrosymmetric [Fe(H2O)6]2+ cation, the isoflavone-3'-sulfonate anions and the solvent water molecules. Additional π-π stacking interactions generate three-dimensional supramolecular structures in both compounds. [ABSTRACT FROM AUTHOR]

The title compound, C18H15BrClN3O2, was obtained by reacting 3-bromo-5-chloro­salicylic aldehyde and 4-amino­anti­pyrine. The structure displays a trans configuration about the imine C=N double bond. The N atom is also involved in an intra­molecular O—H⋯N hydrogen bond, which stabilizes the configuration. [ABSTRACT FROM AUTHOR]

In the structure of the title compound, [Fe(H2O)6](C17H13O7S)2·8H2O, 16 hydrogen bonds exist between the centrosymmetric [Fe(H2O)6]2+ cation, the isoflavone-3′-sulfonate anions and the coordinated and solvent water mol­ecules. π–π stacking inter­actions between the isoflavone units, hydrogen bonding and electrostatic inter­actions result in a three-dimensional supramolecular structure. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C18H11ClN2O4, contains intra- and inter­molecular hydrogen bonds that link the ketone and hydroxyl groups. The inter­molecular hydrogen bond results in the formation of a dimer with an R22(12) graph-set motif. [ABSTRACT FROM AUTHOR]