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Objectives. The paper is devoted to the crystal structure characterization of 5-methyl-2-phenyl4H-pyrazol-3-one (compound I) and 2-(4-chlorophenyl)-5-methyl-4H-pyrazol-3-one (compound II).Methods. Single-crystal X-ray diffraction studies and theoretical calculations: Density functional theory and quantum theory of atoms in molecules.Results. In the solid state, the crystal structure of compound I is characterized by the alternation of OH and NH tautomers connected via O–H---O and N–H---N hydrogen bonds. For compound II, the existence of chains built from the NH monomers via hydrogen bonding can be explained by the peculiarities of cooperative effects. In the framework of quantum theory of atoms in molecules, the following topological characteristics are calculated for all dimers: electron density, Laplacian of electron density, density of kinetic, potential, and total energy in the critical point of the intermolecular hydrogen bond. It is concluded that the hydrogen bond in dimers 1–4, 7 (compound I), and 8–11 (compound II) can be assigned to the intermediate (between covalent and dispersion types) interaction owing to hydrogen bond formation with the participation of electronegative oxygen- (and/or nitrogen-) atoms, whereas H-bond in dimers 5 and 6 (compound I) can be attributed to the dispersion one (no hydrogen bond formation or weak H-bond formation), and it represents the weak interaction, being in agreement with length for intermolecular hydrogen bond in dimers. The electron density and total energy density values demonstrate that the strongest intermolecular H-bonds take place in dimers 1 (OH---O), 4 (OH---O), 7 (OH---N), 8 (OH---O), 9 (NH---N), and 11 (OH---N). The results obtained for compounds I and II are compared with data for antipyrine (1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one; compound III)Conclusions. An important role of intermolecular hydrogen bonding in the crystal packing, molecule association and self-organization via dimer- or more extended species formation has been demonstrated.

This study provides a comparative characterization of the structural parameters and cytotoxicity of zinc halide and copper(II) bromide complexes with caffeine (caf) of the composition [Zn(caf)(H2O)X2] (X = Cl, Br, I) and [Cu(caf)2Br2] (1). The cytotoxicity of the complexes is dose-dependent in all cell lines. The concentrations of the complexes, at which they are more cytotoxic against cancer cells (MCF-7) than against stem cells (DPSC), were determined. The synthesized complexes exhibited synergism of cytotoxicity.

Molecular complexes [Zn(caf)(H2O)I2] (I), [Zn(caf)(H2O)Cl2] (IV), and the polymeric ones {[Cd(H2O)2I2](caf).2H2O}n (II) and {[Cd(H2O)2Br2](caf).2H2O}n (III) consisting of infinite Cd-containing chains with bridging halide ions and water molecules in trans-position and connected with each other due to hydrogen bonding with participation of caffeine (caf) and water molecules, were prepared and characterized by the powder and single crystal X-ray diffraction, IR vibrational spectroscopy, 1H NMR, ESI-MS spectroscopy, thermal analysis and DFT calculations. It was found that the complexes (I) and (IV) are characterized by tetrahedral geometry, the caffeine molecule being coordinated by the central atom via its N9 atom. The preferability of complex formation was evaluated by quantum-chemical calculations. Cyto- and genotoxicity of the compounds have been investigated and discussed in comparison with that of [Zn(AP)2I2] (1) and [Cd(AP)6][Cd(AP)I3]2 (2). It was demonstrated that the prepared complexes, primarily that of cadmium iodide with caffeine (II), are the promising ones for further studies both in vitro and in vivo.

Objective: to study the cytotoxic activity of the zinc (II) and cadmium (II) iodide complexes with antipyrine (AP), caffeine (caf) and 1,10-phenantroline (phen) in comparison with that of free ligands, zinc (II) and cadmium (II) iodides in vitro. Materials and methods. The cytotoxic activity of the zinc (II) and cadmium (II) iodide complexes with AP, caf and phen in comparison with that of free ligands, zinc (II) and cadmium (II) iodides was investigated by methylthiazole tetrazolium assay using 5 human tumor cell lines. Results. It has been found that all 3 cadmium complexes demonstrate cytotoxic activity towards all 5 cell lines with concentration of inhibition of 50 % cell growth 5.5-84.0 mkM. Cytotoxicity of the most active diiodo(1,10-phenantroline)cadmium was slightly above than that of the respective ligand. One zinc-containing complex (diiodo(1,10-phenantroline)zinc) demonstrated significant activity towards 3 cell lines. The Jurkat cells were the most sensitive to studied compounds. Conclusion. It seems that zinc (II) and cadmium (II) iodide complexes with organic ligands are promising ones as potential antitumor drugs for further investigations both in vitro and in vivo.

The synthesis and results of IR spectroscopy and X-ray diffraction analysis of new complexes of biurete NH2CONHCONH2 (BU) with the composition LnCl3 · 2BU · 4H2O, where Ln = La (I), Pr (II), Ho (III), Er (IV), and Lu (V), are presented. Crystals of complexes I–V include complex cations [Ln(H2O)4(BU)2]3+ and uncoordinated chloride ions. The coordination mode of biurete molecules is bidentate through the oxygen atoms, and upon coordination the BU molecules are transformed from the initial trans to cis configuration. Water molecules are also coordinated through the oxygen atom (the shape of the polyhedron of the Ln atoms is a two-capped trigonal prism). The oxygen atoms of both BU molecules and the oxygen atoms of the first and second water molecules form a trigonal prism, whereas the oxygen atoms of the third and fourth water molecules form two caps of the coordination polyhedron. The coordinated BU molecules are joined with the chloride ions and water molecules of the adjacent complex cations by hydrogen bonds. The degree of conversion of trans-BU to cis-BU in the lanthanide series of complexes of this type is discussed.

New complexes of yttrium and lanthanum bromides and erbium chloride with carbamide (Ur), [Y(Ur)4(H2O)4]Br3 (I) and [La(Ur)4(H2O)4]Br3 (II), [La(Ur)6(H2O)2]Br3 (III), and [Er(Ur)6Cl]Cl2 (IV), are synthesized and studied by X-ray diffraction analysis. In structures I–III, the coordination of the ligands (water and carbamide) by the metal occurs through the oxygen atoms. The coordination polyhedron of the rare-earth metal atoms is a distorted square antiprism (coordination number 8), and the bromide ions are not included into the internal coordination sphere of the complexes. In compound IV, the internal coordination sphere of the complex includes six carbamide molecules and one chloride ion, and the coordination polyhedron of Er is a distorted pentagonal bipyramid (coordination number 7). Specific features of the structures of the crystalline carbamide derivatives of chlorides, bromides, and iodides of the considered rare-earth metals are compared. A distortion of the planar structure of some carbamide ligands, depending on their number in the complex cation and on the nature of the complex, is observed.

Data on the synthesis and the IR spectroscopic and X-ray diffraction analyses of new complexes of yttrium chloride with carbamide (Ur), [Y(Ur)4(H2O)4]Cl3 (I) and [Y(Ur)6(H2O)2]Cl3 (II), and with acetamide (AA), [Y(AA)5(H2O)2]Cl3 (III), are presented. The coordination of the ligands occurs through the oxygen atoms. For complexes I and II, the coordination polyhedra of the Y atoms are distorted tetragonal antiprisms. For structure III, the coordination polyhedron of the Y atom is a distorted pentagonal bipyramid. The coordination of four Ur molecules in complex I does not change their planar structure, and two Ur molecules in structure II have the dihedral angle N-C(O)-N different from 180°. The chloride ions are in the external sphere. Many hydrogen bonds are observed in the structures of complexes I–III.

Data on the synthesis, IR spectra, and X-ray diffraction analysis of the thiocarbamide complexes of europium, holmium, and erbium iodides, [Ln(H2O)9]I3 · 2CS(NH2)2 (Ln = Eu (I), Ho(II), Er (III)), are presented. The crystal structures of the complexes contain nonaaqualanthanide cations (the polyhedron shape is a monocapped tetragonal antiprism), outer-sphere thiocarbamide molecules, and uncoordinated iodide ions. The thiocarbamide molecules form hydrogen bonds with the aqua cations and join them into continuous layers or network ensembles. The thiocarbamide molecules are disordered in the crystal structures of complexes II and III.

Scandium, yttrium, lanthanum, cerium, and terbium bromides and iodides of the formulas [(H2O)5Sc(μ-OH)2Sc(H2O)5]Br4 · 2H2O (I), [(H2O)5Sc(μ-OH)2Sc(H2O)5]I4 (II), [Y(H2O)8]Br3 · 2H2O (III), [(H2O)7La(μ-Br)2La(H2O)7]Br4 (IV), [Ce(H2O)9]I3 (V), and [Tb(H2O)9]I3 (VI) were obtained and examined using X-ray diffraction and IR and Raman spectroscopy. It was found that the compositions and structures of complexes II and III differ from the literature data. Crystallographic parameters were obtained for isostructural complexes V and VI. It was demonstrated that the conditions of the synthesis and the possibility of protolysis are decisive for the formation of polynuclear oxo and hydroxo complexes of rare-earth metal halides.

The synthesis and data of the study of new complexes of erbium and lutetium bromides with carbamide, [Ln(Ur)4(H2O)4]Br3 (I and III) and [Ln(Ur)6(H2O)2]Br3 (II and IV) (Ln = Er and Lu), by IR spectroscopy and X-ray diffraction analysis are presented. For all four compounds, coordination with metal occurs through the oxygen atoms of the water and carbamide molecules. The coordination polyhedra of the Ln atoms are distorted square antiprisms. Coordination of four carbamide molecules does not change their planar structures. The bromide ions are not coordinated, existing in the external sphere. Many hydrogen bonds are observed in the structures of complexes of both types.

New acetamide and carbamide complexes LnI3 · 4Ur · 4H2O (Ln = La, Eu, Dy, Ho, Y; Ur is carbamide) and LnI3 · 4AA · 4H2O (Ln = Nd, Eu, Dy, Ho, Y; AA is acetamide) are synthesized. The complexes are characterized by the data of chemical analysis, IR spectroscopy, and X-ray diffraction analysis. The ligands (water, carbamide, and acetamide molecules) are coordinated by the rare-earth element atoms through the oxygen atom, and the coordination polyhedron is a distorted square antiprism. The iodide ions are not coordinated and are located in the external sphere. The structural characteristics of the complexes are compared in the series [Ln(L)4(H2O)4]I3 (Ln = La, Nd, Eu, Gd, Dy, Ho, Er; L = AA, Ur).

The crystal and molecular structures of 4-alkoxybenzoic acids C n H2n + 1-O-C6H4-COOH, n = 4–12, which are nematic (n = 4–6) or smectic-nematic (n = 7–12) mesogenes, are studied. No direct relationship between the molecular geometry and mesogenic properties is found. All the crystal structures contain dimers formed by pairs of O…H-O hydrogen bonds between carboxyl groups. Crystals belonging to the group of smectic-nematic liquid crystals (SNLC) are built of separate regions, namely, loosely packed aliphatic regions and closely packed aromatic regions with significant π-stacking interactions. Loose aliphatic regions occur in crystals belonging to the group of nematic liquid crystals (NLC); however, they are surrounded by dense aromatic regions and do not run throughout the crystal. In NLC, π-stacking interactions are far weaker than in SNLC. At the early stage of melting of SNLC crystals, structurized associates due to both π-stacking interactions and hydrogen bonds are retained in the melt (smectic phase), whereas, upon further heating, only hydrogen-bonded associates are left (nematic phase). In the course of melting of NLC, only hydrogen-bonded dimers are retained in the melt (nematic phase).

New acetamide complexes of lanthanum, gadolinium, and erbium iodides of the composition LnI3 · 4AA · 4H2 O (Ln = La, Gd, Er; AA = CH3CONH2) are synthesized and studied. The synthesized complexes are characterized by the data of chemical analysis and IR spectroscopy and are studied by X-ray diffraction analysis. The coordination of the ligands (water and acetamide molecules) by the lanthanum, gadolinium, or erbium atom occurs through the oxygen atoms. The coordination polyhedron of the Ln atom is a distorted square antiprism. The iodide ions are not coordinated and exist in the external sphere.

Synthesis and X-ray single-crystal diffraction study of antipyrine complexes of lanthanum, europium, and scandium iodides were performed. In all compounds, the inner coordination sphere of the complex cation is an octahedron formed by antipyrine molecules coordinated through the oxygen atoms of the C=O groups.

The novel carbamide complexes of gadolinium and erbium iodides of the composition LnI34Ur·4H2O (Ln = Gd, Er; Ur = carbamide) were synthesized and studied by X-ray diffraction and IR spectroscopy. The ligands are coordinated to the central Gd or Er atom through the O atoms of water or carbamide molecules. The coordination polylhedron of Ln atoms is a distorted square antiprism. The iodide ions are not coordinated and lie in the outer sphere.

The triclinic modification of para-n-hexyloxybenzoic acid is studied using X-ray diffraction analysis (MoK α radiation) at 120 K. The crystallographic parameters of the compound are as follows: space group, $$P\overline 1 $$ a = 7.8854(4) A, b = 14.3021(7) A, c = 33.0513(16) A, α = 88.738(1)°, β = 85.701(1)°, γ = 78.331(1)°, and Z = 12. The asymmetric unit of the crystal contains six molecules of the acid with different orientations of the aliphatic chain. In the crystal, the molecules are joined into dimers by hydrogen bonds between the carboxyl groups. The crystal packing is built on the principle of the separation of aromatic and aliphatic regions.

New hexanuclear complexes of lanthanum and neodymium iodides, [La6(H2O)23(OH)10]I8 · 8H2O (I) and [Nd6(H2O)23(OH)10]I8 · 8H2O (II), are synthesized and studied by X-ray diffraction analysis. The isostructural crystals of complexes I and II are orthorhombic: a = 13.197(4) A, b = 15.152(3) A, c = 15.302(4) A and a = 13.060(4) A, b = 14.967(5) A, c = 15.098(4) A, respectively; Z = 2, space group Pnnm. The lanthanum (neodymium) atoms coordinate the aqua and hydroxo ligands and enter the composition of the Ln6 -containing complex cations. The coordination polyhedron (ignoring the central oxygen atom) of each atom of the complexing agent is somewhat distorted square antiprism with the aqua and hydroxo ligands being in the vertices. Four bridging ligands link this atom of the complexing agent with the four adjacent atoms.

Physicochemical properties and X-ray diffraction data for [Ln(C11H12N2O)6]I3 were considered. The properties and stability of the complexes were compared along the lanthanide series.

The carbamide complexes of lanthanide polyiodoiodates [Tm(ur)7][I3]3·2I2, [Yb(ur)6][I3]3 and [Lu(ur)6][I3]3 [ur is O=C(NH2)2] have been synthesized and structurally characterized. The structure-forming role of the pentaiodide ions taking part in the formation of extended channels 10–12 A in diameter with incorporated hepta(carbamide)thulium cations combined to one another into infinite columns due to H-bonding, or the triiodide ions forming lace-like net with isolated hexa(carbamide)ytterbium(iii) or hexa(carbamide) lutetium(iii) cations located in the net holes has been revealed.