Pyrimidine Schiff Bases: Synthesis, Structural Characterization and Recent Studies on Biological Activities.

Recently, 5-[(4-ethoxyphenyl)imino]methyl-N-(4-fluorophenyl)-6-methyl-2-phenylpyrimidin-4-amine has been synthesized, characterized, and evaluated for its antibacterial activity against in combination with antineoplastic activity against gastric adenocarcinoma. In this study, new 5-iminomethylpyrimidine compounds were synthesized which differ in the substituent(s) of the aromatic ring attached to the imine group. The structures of newly obtained pyrimidine Schiff bases were established by spectroscopy techniques (ESI-MS, FTIR and H NMR).

Conformation of the hydrazo bond in new 2-methyl-3,5-dinitro-6-(2-phenylhydrazinyl)pyridine and its influence on the structural and optic properties - Quantum chemical DFT calculations.

A new methyl-dinitro-phenylhydrazinyl-pyridine derivative [2-methyl-3,5-dinitro-6-(2-phenylhydrazinyl)pyridine] was synthesised and characterised by means of structural and spectroscopic measurements. The X-ray diffraction studies revealed that the compound crystallises in the centrosymmetric monoclinic space group P2/n, with two symmetry-independent molecules in the asymmetric unit with Z = 8. Hydrazo bridge C-NH-NH-C links two fragments composed of phenyl ring and pyridine unit substituted with methyl and nitro groups.

Structure and cytotoxic properties of 1-hydroxy-5-methyl-7-phenylpyrido[3,4-d]pyridazin-4(3H)-one and its mono- and disubstituted ethyl acetates.

Derivatives of pyrido[3,4-d]pyridazine, namely, 1-hydroxy-5-methyl-7-phenylpyrido[3,4-d]pyridazin-4(3H)-one dimethylformamide monosolvate, CHNO·CHNO (2), ethyl [1-(2-ethoxy-2-oxoethoxy)-5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-3-yl]acetate, CHNO (3), and ethyl [(5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-1-yl)oxy]acetate, CHNO (4), were synthesized with the aim of discovering new potential biologically active agents. The properties of all three derivatives were characterized by H NMR, C NMR and FT-IR spectroscopic analysis. All the crystals were obtained by a solvent diffusion method from dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) and characterized by single-crystal X-ray diffraction.

Synthesis, Structural Characterization and Anticancer Activity of New 5-Trifluoromethyl-2-thioxo-thiazolo[4,5-]pyrimidine Derivatives.

Thiazolo[4,5-]pyrimidine derivatives are considered potential therapeutic agents, particularly in the development of anticancer drugs. In this study, new 7-oxo-(), 7-chloro-() and also three 7-amino-() 5-trifluoromethyl-2-thioxo-thiazolo[4,5-]pyrimidine derivatives have been synthesized and evaluated for their potential anticancer activity. These derivatives were characterized by spectroscopic methods and elemental analysis, and the single-crystal X-ray diffraction was further performed to confirm a 3D structure for compounds and .

Synthesis, Crystal Structure, and Biological Evaluation of Novel 5-Hydroxymethylpyrimidines.

Pyrimidine displays a wide array of bioactivities, and thence, it is still considered a potent unit of new drug research. Its derivative, 5-hydroxymethylpyrimidine, can be found as a scaffold of nontypical nitrogen bases in DNA and as a core of some natural bioactive compounds. In this study, we obtained a series of 5-hydroxymethylpyrimidines that vary in the 4-position by the reduction of proper esters.

A New Pyrimidine Schiff Base with Selective Activities against and Gastric Adenocarcinoma.

is known as a significant nosocomial pathogen due to its natural resistance to many antibacterial drugs. Moreover, it was found that infection causes inflammation, production of reactive oxygen species, and DNA damage to human gastric cancer cells, which can induce cancer. In this study, we synthesized and tested the biological activity of a new Schiff base, 5-[(4-ethoxyphenyl)imino]methyl--(4-fluorophenyl)-6-methyl-2-phenylpyrimidin-4-amine (), and compared its properties with an analogous amine ().

Synthesis and Biological Activity of New 7-Amino-oxazolo[5,4-]Pyrimidine Derivatives.

The synthesis of a series of novel 7-aminooxazolo[5,4-]pyrimidines , transformations during their synthesis and their physicochemical characteristics have been described. Complete detailed spectral analysis of the intermediates -, the -cyanooxazolylacetamidine by-products and final compounds has been carried out using MS, IR, 1D and 2D NMR spectroscopy. Theoretical research was carried out to explain the privileged formation of 7-aminooxazolo[5,4-]pyrimidines in relation to the possibility of their isomer formation and the related thermodynamic aspects.

Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide - Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations.

The crystal and molecular structure and physicochemical properties of 2--methylamino-3-methylpyridine -oxide (MA3MPO) have been studied. MA3MPO was synthesized from 2-amino-3-methylpyridine by several steps to form colorless crystals suitable for crystallographic analysis. The data reveal that MA3MPO crystallizes in the monoclinic space group 2/.

The '-Substituted Derivatives of 5-Chloro-3-Methylisothiazole-4-Carboxylic Acid Hydrazide with Antiproliferative Activity.

Thanks to the progress in oncology, pharmacological treatment of cancer is gaining in importance and in the near future anti-cancer chemotherapeutics are expected to be the main method of treatment for cancer diseases. What is more, the search for new anti-cancer compounds with the desired application properties is constantly underway. As a result of designed syntheses, we obtained some new '-substituted 5-chloro-3-methylisothiazole-4-carboxylic acid hydrazide derivatives with anticancer activity.

Synthesis, crystal structure and cytotoxic activity of novel 5-methyl-4-thiopyrimidine derivatives.

This article presents the synthesis of three new 4-thiopyrimidine derivatives obtained from ethyl 4-methyl-2-phenyl-6-sulfanylpyrimidine-5-carboxylate as the starting material, namely, ethyl 4-[(4-chlorobenzyl)sulfanyl]-6-methyl-2-phenylpyrimidine-5-carboxylate, CHClNOS, (2), {4-[(4-chlorobenzyl)sulfanyl]-6-methyl-2-phenylpyrimidin-5-yl}methanol, CHClNOS, (3), and 4-[(4-chlorobenzyl)sulfanyl]-5,6-dimethyl-2-phenylpyrimidine, CHClNS, (4), which vary in the substituent at the 5-position of the pyrimidine ring. The compounds were characterized by H NMR, C NMR, IR and mass spectroscopies, and also elemental analysis. The molecular structures were further studied by single-crystal X-ray diffraction.

Conformation of the azo bond and its influence on the molecular and crystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine - Quantum chemical DFT calculations.

The crystal and molecular structures of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine have been determined by X-ray diffraction and quantum chemical DFT calculations. The crystal is monoclinic, space group Cc (No. 9) with Z=4 with the unit cell parameters: a=12.

Synthesis and antibacterial properties of pyrimidine derivatives.

In this study, a series of syntheses was conducted on the pyrimidine system, obtaining bisulfite carboxyl derivatives 4 and hydroxy derivatives 5. In addition, a series of syntheses were carried out as a result of which both alkyl and aromatic amines were obtained. Then, the attempt was made to cyclize these amines in the Mannich reaction to pyrimido[4,5-d]pyrimidines 11, 12.

The hydrazo-bond in 4,4'-dimethyl-3,3'-dinitro-2,2'-hydrazobipyridine - crystal structure, conformation and vibrational characteristics.

The crystal and molecular structure of 4,4'-dimethyl-3,3'-dinitro-2,2'-hydrazobipyridine have been determined by X-ray diffraction and quantum chemical DFT analysis. The title compound crystallizes in P1¯ space group, with one-half molecule in the asymmetric unit. The molecular structure is stabilized by intramolecular NH···O hydrogen bonds.

N-(4-Meth-oxy-phen-yl)-6-methyl-2-phenyl-5-{[4-(tri-fluoro-meth-yl)anilino]meth-yl}pyrimidin-4-amine.

The title compound, C26H23F3N4O, crystallizes with two symmetry-independent mol-ecules in the asymmetric unit, denoted A and B, which differ mainly in the rotation of the meth-oxy-phenyl ring. The -CF3 group of mol-ecule B is disordered by rotation, with the F atoms split over two sets of sites; the occupancy factor for the major component is 0.853 (4).

The role of hydrogen bonds in the crystals of 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate and 4-hydroxybenzenesulfonate - X-ray and spectroscopic studies.

Two new organic-organic salts, 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate (AMNP-TFA), and 2-amino-4-methyl-5-nitropyridinium 4-hydroxybenzenesulfonate (AMNP-HBS), were obtained and characterized by means of FT-IR, FT-Raman and single crystal X-ray crystallography. In the former crystal, the cations, anions and water molecules are linked into layers by three types of hydrogen bonds, NPH⋯O, NAH⋯O and OH⋯O. These layers are connected by weaker CH⋯O hydrogen bonds.

Comprehensive physicochemical studies of a new hybrid material: 2-amino-4-methyl-3-nitropyridinium hydrogen oxalate.

A new organic-organic salt, 2-amino-4-methyl-3-nitropyridinium hydrogen oxalate (AMNPO), and its deuterium analogue have been synthesized and characterized by means of FT-IR, FT-Raman, DSC and single crystal X-ray studies. The DSC measurements and temperature dependence of the IR and Raman spectra in the range 4-295 K show that it undergoes a reversible phase transition at ~240 K. At room temperature it crystallizes in noncentrosymmetric space group P21.

5-[(3,5-Dichloro-anilino)meth-yl]-N-(3,5-dichloro-phen-yl)-6-methyl-2-phenyl-pyrimidin-4-amine.

In the title compound, C24H18Cl4N4, the pyrimidine ring makes dihedral angles of 19.1 (2), 4.1 (2) and 67.

Vibrational spectra, crystal structure, DFT quantum chemical calculations and conformation of the hydrazo-bond in 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine.

The crystal and molecular structures of 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-3-nitro-2-phenylhydrazopyridine) have been determined by X-ray diffraction and quantum chemical DFT analysis. The crystal is monoclinic, space group C2/c, with Z=8 formula units in the elementary unit cell of dimensions a=16.791(4), b=6.

5-[(4-Fluoro-anilino)meth-yl]-6-methyl-N-(4-methyl-phen-yl)-2-phenyl-pyrimidin-4-amine.

In the title compound, C(25)H(23)FN(4), the pyrimidine ring makes dihedral angles of 11.3 (2), 24.5 (2) and 70.

Molecular and crystal structures, vibrational studies and quantum chemical calculations of 3 and 5-nitroderivatives of 2-amino-4-methylpyridine.

The crystal structures of 2-amino-4-methyl-3-nitropyridine (I), 2-amino-4-methyl-3,5-dinitropyridine (II) and 2-amino-4-methyl-5-nitropyridine (III) have been determined. The compounds crystallize in the monoclinic P2(1)/n, triclinic P-1 and monoclinic C2/c space groups, respectively. These structures are stabilized by a combination of N-H···N and N-H···O hydrogen bonds and exhibit layered arrangement with a dimeric N-H···N motif in which the molecular units are related by inversion centre.

5-[(4-Eth-oxy-anilino)meth-yl]-N-(2-fluoro-phen-yl)-6-methyl-2-phenyl-pyrimidin-4-amine.

The asymmetric unit of the title compound, C(26)H(25)FN(4)O, consists of two symmetry-independent mol-ecules, denoted A and B. The conformation of each mol-ecule is mainly determined by an intra-molecular N-H⋯N hydrogen bond, which closes a six-membered ring. The dihedral angles between the pyrimidine ring and the phenyl, fluorophenyl and ethoxyphenyl rings are 15.

N-(2-Fluoro-phen-yl)-5-[(4-meth-oxy-phen-yl)amino-meth-yl]-6-methyl-2-phenyl-pyrimidin-4-amine.

The conformation of the title mol-ecule, C(25)H(23)FN(4)O, is mainly determined by an intra-molecular N-H⋯N hydrogen bond closing a six-membered ring and the dihedral angles between the pyrimidine ring and the three benzene rings which are 12.8 (2), 12.0 (2) and 86.

Synthesis and antibacterial properties of pyrimidine derivatives.

The paper presents the synthesis of 1,2,3,7-tetraaryl-1,2,3,4-tetrahydropyrimido[4,5-d]pyrimidines. The structures of the obtained compounds were confirmed by crystallographic and spectroscopic analyses, and their antibacterial activity was tested on 9 selected strains, comparing chemical structure changes with increased microbiological activity. It was confirmed that aromatic residues in the hydrogenated pyrimidine ring constitute a significant element influencing antibacterial activity.

Synthesis and antibacterial properties of 1,2,3-aryl-1,2,3,4-tetrahydropyrimido[4,5-d]pyrimidine derivatives.

The 1,2,3-aryl-1,2,3,4-tetrahydropyrimido[4,5-d]pyrimidine derivatives have been synthesized and evaluated as antibacterial agents. The X-ray crystallography study has been undertaken to confirm structure of 2-(4-chlorophenyl)-,1 3-di-(4-methoxyphenyl)-5-methyl-7-phenyl- ,2,3,4-tetrahydropyrimido[4,5-d]pyrimidine. The antibacterial properties were tested using six selected strains by comparing changes of chemical structures with growth of biological activity.

Elucidation of structural restraints for phosphate residues with different hydrogen bonding and ionization states.

Solid state NMR spectroscopy and gauge including atomic orbital (GIAO) theoretical calculations were employed to establish structural restraints (ionization, hydrogen bonding, spatial arrangement) for O-phosphorylated l-threonine derivatives in different ionization states and hydrogen bonding strengths. These structural restraints are invaluable in molecular modeling and docking procedures for biological species containing phosphoryl groups. Both the experimental and the GIAO approach show that 31P delta ii chemical shift tensor parameters are very sensitive to the ionization state.