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Biological active compounds on the basis of 3-amino-5-phenylthiazolidin-2-iminium bromide were synthesized, and their biological activity was studied. The structures of the synthesized compounds were confirmed by 1H and 13C NMR spectroscopy and X-ray diffraction analysis.

3-Amino-5-phenyl-1,3-thiazolidin-2-iminium bromide was synthesized for the first time by reaction of (1,2-dibromoethyl)benzene with thiosemicarbazide hydrochloride. Its condensation with aromatic aldehydes afforded the corresponding Schiff bases. The structure of the isolated compounds was confirmed by 1H and 13C NMR spectroscopy.

The reaction of 5-acetyl-4-aryl-6-hydroxy-3,6-dimethyl-4,5,6,7-tetrahydroindazoles p-toluenesulfonyl chloride in boiling acetone in the presence of triethylamine was found to occur in a completely regioselective with the exclusive formation of 5-acetyl-4-aryl-6-hydroxy-3,6-dimethyl-1-(4-methylbenzenesulfonyl)-4,5,6,7-tetrahydroindazoles. The experimental results were confirmed by quantum chemical calculations. In silico biological activity evaluation of the synthesized compounds was performed.

New tetrahydroisoquinoline-5,7-dicarbonitrile derivatives have been synthesized by piperazine hydrate-catalyzed reaction of acetoacetanilide with 2-(1-arylethylidene)malononitriles (Knoevenagel condensation products of acetophenones and malononitrile) in aqueous ethanol at room temperature. The product structure was confirmed by NMR spectra and X-ray analysis of 1,6-diamino-4a-methyl-3-oxo-2,8-diphenyl-2,3,4,4a-tetrahydroisoquinoline-5,7-dicarbonitrile.

Three-component condensation of benzylideneacetone, ethyl acetoacetate, and malononitrile in the 1:1:1 molar ratio, respectively, in the presence of equimolar quantities of piperidine and glacial acetic acid is studied. The crystal structure of the reaction product (ethyl-2-dicyanomethylene-4-methyl-6-phenyl-3-cyclohexene-1-carboxylate) determined from XRD data by the method of atom-atom potentials contains energy traps in the form of double planar and double two-sided catchers. The energy traps lead to molecular agglomerates occurring in the crystal in the form of slightly deformed translationally identical hexagonal networks.

In this paper are described the results of the studies, devoted to the investigations of quaternary salt of 2-allyl-4-isooctyl-6-piperidinomethylphenol as corrosion inhibitor of the non-alloy steel in the system, consisting of 3% water solution of NaCl and hydrocarbons (kerosene) at ratio 9 : 1.

Michael addition of various substituted benzylidene- and thiophen-2-ylmethylidenemalononitriles with acetoacetanilide gave the corresponding 5-acetyl-2-amino-4-aryl(hetaryl)-6-oxo-1-phenyl-1,4,5,6-tetrahydropyridine-3-carbonitriles. Treatment of the latter with ethylenediamine in boiling methanol resulted in their rearrangement with elimination of the acetyl group and formation of 2-anilino-4-aryl(hetaryl)-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles. The product structure was proved by NMR spectroscopy and X-ray analysis.

As a result of triple condensation of malonodinitrile with benzaldehyde and ethyl 2-chloro-3-oxobutanoate a compound with 3-azabicyclo[3.1.0]hexane framework is formed whose crystal structure is determined by X-ray crystallography. In the crystal structure a layered character of the molecular packing is found. Molecules are linked in the layer by H bonds of N-H…O=C and C-H…O=C types and also a large number of atom-atom contacts whose energy corresponds to potential wells.

The molecular and crystal structures of 1-(4-fluorophenyl)-1,4-dihydro-1H-tetrazole-5-thione (I) and its complex with cadmium(II) (II) are studied by single crystal XRD. Free ligand I is thione; it has a nonplanar structure (the torsion angle between the tetrazole and benzene rings is 54.99(7)°) and forms H-bonded centrosymmetric dimers via two N–H…S hydrogen bonds in the crystal. The dimers contain a central planar eight-membered {S=C–N–H…S=C–N–H…} ring. Complex II has a chain structure with the composition [(C7H4N4FS)2Cd]n. The environment of the Cd(II) atom consists of two nitrogen atoms and two sulfur atoms from four ligands I and represents a distorted tetrahedron. When complex II forms, ligand I converts into the thiol form. Infinite 1D chains contain eight-membered {←S=C–N–Cd←S=C–N–Cd} rings in a chair conformation. The chains in the crystal are arranged in layers parallel to the (101) plane due to secondary intermolecular F…F and π–π-stacking interactions.

We report a novel three-component condensation of benzalacetophenone, ethyl acetoacetate, and malonodinitrile in a 1:1:1 molar ratio respectively, involving an equimolar amount of morpholine acetate to form ethyl-4,6(R,S)-diphenyl-2-dicyanomethylenecyclohex-3-ene-1(R,S)-carboxylate whose crystal structure is determined by single crystal XRD. The intermolecular interaction is analyzed using an atomatom potential model, and infinite chains of energetically tightly coupled molecules in the crystal structure are identified and described. A weak hydrogen bond of the CAr–H…O type is found.

The efficiency of (2E,4E)-1-(2-hydroxy-5-methylphenyl)-5-phenyl-2,4-pentadiene-1-one (1), (2E)-3-[2-(allyloxy)-5-bromophenyl]-1-(2-hydroxy-5-methylphenyl)-2-propen-1-one (2), (E)-4-methyl-2-(3-methyl-4-styryl-4.5-dihydrobenzoisoxazol-6-yl)phenol (3) and 2-{4-[2-(allyloxy)-5-bromophenyl]-3-methyl-4.5-dihydro-1.2-benzisoxazol-6-yl}-4-methylphenol (4) as corrosion inhibitors have been studied by weight loss measurements for St-3 mild steel specimen in brine-kerosene mixture. The corrosion rates of St‑3 steel decreased with increase in concentration of the studied compounds.

Ethyl 3,3,5,5-tetracyano-2-hydroxy-2-methyl-4,6-diphenylcyclohexane-1-carboxylate was synthesized for the first time by three-component condensation of benzaldehyde with ethyl acetoacetate and malononitrile in the presence of trichloroacetic acid. The product structure was proved by X-ray analysis.

The reaction of 2,4-diacetyl-5-hydroxy-5-methyl-3-phenylcyclohexanone-1 with phenylhydrazine is conducted, and the crystal structures of its products, 1-(6-hydroxy-3,6-dimethyl)-2,4-diphenyl-4,5,6,7-tetrahydro-2H-indazol-5-yl)ethane-1-one and 1-(2-hydroxy-2-methyl-6-phenyl-4-(2-phenylhydrazono)-5-(1-(2-henylhydrazono)ethyl)cyclohexyl)ethane-1-one, are determined by single crystal XRD.

A new copper(II) complex with acetylacetone and ethylenediamine is obtained using the template synthesis. It is studied by single crystal X-ray diffraction. The crystals are monoclinic: а = 7.7563(4) A, b = 24.0157(12) A, c = 24.6353(13) A, β = 91.9490(10)°, V = 4586.2(4) A3, space group P2(1)/c, Z = 2, d calc = 1.713 g/cm3, R = 0.0695. The copper atom environment consists of two oxygen and two nitrogen atoms of the ligand, forming a slightly distorted square.

A new complex of copper (II) with 3-(2-hydroxy-3-sulfo-5-nitrophenylazo)-pentadione-2,4 (HL) is synthesized and analyzed by single crystal XRD. The crystals are monoclinic: a = 7.7563(4) A, b = 24.0157(12) A, c = 24.6353(13) A, β = 91.9490(10)°, V = 4586.2(4) A3, space group P21/c, Z = 2, ρcalc = 1.713 g/cm3, R = 0.0695. The environment of the copper atom is formed by three oxygen atoms, the nitrogen atom of tetradentate ligand, and the oxygen atom of a water molecule.

The reaction of diethyl-5-methyl-3-oxo-1,2,3,6-tetrahydro-[1,1′-diphenyl]-2,6-dicarboxylate with (1-(4-bromophenyl)ethylidene)hydrazine is conducted, and the crystal structure of the product of this reaction (diethyl-5-(2-(1-(4-bromophenyl)ethylidene)hydrazinyl)-3-methyl-1,2-dihydro-[1,1′-diphenyl]-2,6-dicarboxylate) is determined by single crystal X-ray diffraction. The conformation of the cyclohexadiene ring in the form of a strongly distorted half-chair is determined based on the X-ray diffraction data. The presence of the intramolecular hydrogen bond of the N–H…O=C type is noted.

The copper(II) complex with 3-(2-hydroxy-3-sulfo-5-nitrophenylhydrazo)pentane-2,4-dione (H3L) is studied, and its crystal structure is studied by X-ray diffraction analysis. The crystals of [Cu(H2O)2]2(μ-L)2[Cu(H2O)4] (I) are triclinic (space group P\( \bar 1 \)) at 100 K, a = 7.085(3), b = 10.373(5), c = 12.265(6) A, α = 0.842(5)°, β = 104.996(6)°, γ = 99.156(6)°, Z = 1). The C=O and NH groups of hydrazone and the OH and SO3H groups from the aromatic moiety of the molecule are involved in coordination with the copper(II) atom. In the centrosymmetric trinuclear molecule the central Cu(2) atom has the coordination number six, and the terminal Cu(1) atoms have the coordination number five. The thermal properties of complex I are studied. The complex formation of copper(II) with the H3L ligand in an aqueous solution at temperatures 298 ± 0.5, 308 ± 0.5, and 318 ± 0.5 K is studied by potentiometric titration. The standard thermodynamic functions of the complex formation are determined.