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=12.083(7), b=12.881(6), c=8.134(3) Å and ß=97.09(5)°. The azo-bridge appears in the trans conformation in which C2-N2-N2'-C1' torsion angle takes a value -178.6(3)°, whereas the dihedral angle between the planes of the phenyl and pyridine rings is 3.5(2)°. The IR and Raman spectra measured in the temperature range 80-350K and quantum chemical calculations with the use of B3LYP/6-311G(2d,2p) approach confirmed the trans configuration of the azo-bridge as the most stable energetically and allowed determination of the energy other virtual structures. The observed effects were used in the discussion of vibrational dynamics of the studied compound. The energy gap between cis and trans conformers equals to 1.054eV (0.03873 Hartree). The electron absorption and emission spectra have been measured and analyzed on the basis of DFT calculations. The life time of the excited state is 12µs and the Stokes shift is close to 5470cm-1.

Spectrally-resolved third-harmonic generation and the fundamental role of O-HCl hydrogen bonding in Oh, Td-cobalt(ii) tetraphenylmethane-based coordination polymers.

The reaction of a phosphonate-diester tetraphenylmethane-based tecton, tetrakis[4-(diethoxyphosphoryl)phenyl]methane, (L) with cobalt(ii) chloride afforded a centrosymmetric coordination polymer (CP), [L·2Co(H2O)42+·2CoCl42-]n, 2-Cl, possessing simultaneously octahedral (Oh) and tetrahedral (Td) metal centers. This material served as a model compound for the demonstration of factors influencing the spectral dependence of one of the nonlinear optical (NLO) phenomena, the third-harmonic generation (THG). The spectrally-resolved THG (SR-THG) measurements in the range from 1125 to 1750 nm revealed that a maximum of THG response is obtained when the fundamental beam is around 1300 nm. The SR-THG study was combined with an analysis of the self-absorption effects of pumping and of third-harmonic radiation; based on these results, we put forward a hypothesis that the THG action spectrum is influenced more by the ability of the material to self-absorb the third harmonic rather than by the extent of self-absorption of the pumping radiation. Apart from investigations of NLO properties, we have explored coordination and particularly the supramolecular interactions that build up the 2-Cl CP. Despite the tetrahedral, spatial shape of the ligand L, CP 2-Cl has a two-dimensional net. The structure was found to be strongly supported by O-HCl hydrogen bonds, since each CoCl42- complex anion is an acceptor of eight of such interactions within a distorted square grid layer of cobalt(ii) ions. While coordination and hydrogen-bonded nets are both featuring the sql topology when treated separately, the consideration of both of them as topological paths yields a trinodal 4,4,6-connected net, described by the point symbol (42·84)(45·6)2(46·66·83)2. SR-THG and structural studies of 2-Cl have been also supported by far- and mid-infrared spectroscopy, UV-Vis-NIR solid state absorption analysis, thermogravimetry and preliminary magnetic characterization.

Structure, vibrational spectra and DFT characterization of the intra- and inter-molecular interactions in 2-hydroxy-5-methylpyridine-3-carboxylic acid--normal modes of the eight-membered HB ring.

Fourier transform IR and Raman spectra, XRD studies and DFT quantum chemical calculations have been used to characterize the structural and vibrational properties of 2-hydroxy-5-methylpyridine-3-carboxylic acid. In the unit-cell of this compound two molecules related by the inversion center interact via OH⋯N hydrogen bonds. The double hydrogen bridge system is spaced parallel to the (102) crystallographic plane forming eight-membered arrangement characteristic for pyridine derivatives. The six-membered ring is the second characteristic unit formed via the intramolecular OH⋯O hydrogen bond. The geometry optimization of the monomer and dimer have been performed applying the Gaussian03 program package. All calculations were performed in the B3LYP/6-31G(d,p) basis set using the XRD data as input parameters. The relation between the molecular and crystal structures has been discussed in terms of the hydrogen bonds formed in the unit cell. The vibrations of the dimer have been discussed in terms of the resonance inside the system built of five rings coupled via hydrogen bonds.

Crystal and molecular structure of N-(4-nitrophenyl)-ß-alanine--its vibrational spectra and theoretical calculations.

The N-(4-nitrophenyl)-ß-alanine in crystalline form directly by the addition of 4-nitroaniline to the acrylic acid in aqueous solution has been obtained. The title ß-alanine derivative crystallizes in the P2(1)/c space group of monoclinic system with four molecules per unit cell. The X-ray geometry of ß-alanine derivative molecule has been compared with those obtained by molecular orbital calculations corresponding to the gas phase. In the crystal the molecules related by an inversion center interact via symmetrically equivalent O-H···O hydrogen bonds with O···O distance of 2.656(2) Å forming a dimeric structure. The dimers of ß-alanine derivative weakly interact via N-H···O hydrogen bonds between the H atom of ß-amine groups and one of O atom of nitro groups. The room temperature powder vibrational (infrared and Raman) measurements are in accordance with the X-ray analysis. In aqueous solution of 4-nitroaniline and acrylic acid, the double CC bond of vinyl group of acrylic acid breaks as result of 4-nitroaniline addition.

Bis(melaminium) sulfate dihydrate.

The crystals of a new melaminium salt, bis(2,4,6-triamino-1,3,5-triazin-1-ium) sulfate dihydrate, 2C3H7N6+*SO4(2-)*2H2O, are built up from monoprotonated melaminium(1+) residues, sulfate(2-) anions and water molecules. The SO4(2-) ion has a slightly distorted tetrahedral geometry. The melaminium residues are interconnected by N-H.N hydrogen bonds, forming chains. The chains of melaminium residues develop a three-dimensional network through multiple donor-acceptor hydrogen-bond interactions with sulfate anions and water molecules.

Melaminium chloride hemihydrate.

The crystals of a new melaminium salt, 2,4,6-triamino-1,3,5-triazin-1-ium chloride hemihydrate, C(3)H(7)N(6)(+).Cl(-).0.5H(2)O, are built up from single-protonated melaminium residues, chloride anions and water molecules. The protonated melaminium cations lie on a twofold axis, while the chloride anions and water molecule lie on the m plane. The melaminium residues are interconnected by N-H...N hydrogen bonds, forming chains parallel to the (001) plane. The chains of melaminium residues form a three-dimensional network through hydrogen-bond interactions with chloride anions and water molecules.

Iodo(phthalocyaninato)chromium(III).

A new chromium(III)-phthalocyanine complex with the formula [Cr(C(32)H(16)N(8))I], or CrPcI where Pc is phthalocyanate(2-), has been obtained by the reaction of pure Cr powder with phthalonitrile under a stream of iodine vapour. The five-coordinate Cr atom is bonded to the four isoindole N atoms of the phthalocyaninate(2-) ligand and to one apical iodine ligand, and has a square-pyramidal coordination geometry. The Cr(III) cation is significantly displaced [0.456 (2) A] from the N(4)-isoindole plane towards the I atom. The Cr-I bond is tilted 2.51 (4) degrees to the N(4)-isoindole plane.

Melaminium bis(4-hydroxybenzenesulfonate) dihydrate.

The crystals of a new melaminium salt, 2,4,6-triamino-1,3,5-triazine-1,3-diium bis(4-hydroxybenzenesulfonate) dihydrate, C3H8N6(2+)*2C6H5O4S-*2H2O, are built up from doubly protonated melaminium(2+) residues, dissociated p-phenolsulfonate anions and water molecules. The doubly protonated melaminium dication lies on a twofold axis. The hydroxyl group of the p-hydroxybenzenesulfonate residue is roughly coplanar with the phenyl ring [dihedral angle 13 (2) degrees ]. A combination of ionic and donor-acceptor hydrogen-bond interactions link the melaminium and p-hydroxybenzenesulfonate residues and the water molecules to form a three-dimensional network.

A peptide derived from neutrophil inhibitory factor (NIF) blocks neutrophil adherence to endothelial cells.

OBJECTIVE AND DESIGN: Peptides derived from neutrophil inhibitory factor (NIF), a known antagonist of Mac-1, were evaluated as inhibitors of neutrophil adherence. MATERIAL: In vitro assays of adherence employed: 1) human polymorphonuclear cells (PMN), 2) human umbilical vein endothelial cells (HUVEC), and 3) CHO cells expressing ICAM-1 (CHO-ICAM cells). TREATMENT: Cells, pretreated with NIF-derived peptides (0.1-100 microM) for 10 minutes, were permitted to adhere for 20 min in the continued presence of peptide. METHODS: Cell-based assays: 1) PMN adherence to HUVEC, 2) PMN adhesion to immobilized human serum proteins, and 3) adherence of CHO-ICAM cells to immobilized Mac-1. RESULTS: A NIF-derived peptide of 29 amino acids blocked PMN adherence to HUVEC, but behaved somewhat differently than the parent NIF protein. NIF specifically antagonized Mac-1 dependent adherence, but the peptide blocked neutrophil adherence that was dependent upon both Mac-1 and LFA-1 integrins. CHO-ICAM adherence to Mac-1 was blocked by NIF, but not by the peptide. Binding studies with NIF and the peptide indicate that the molecules bind to different sites. CONCLUSIONS: A peptide derived from NIF blocks PMN adherence but, unlike NIF, the mechanism of action is not mediated by direct antagonism Mac-1.

Fluorenylalkanoic and benzoic acids as novel inhibitors of cell adhesion processes in leukocytes.

A series of fluoren-9-ylalkanoic and alkylbenzoic acids was prepared as simplified analogues of a previously reported series of antiinflammatory agents which act to inhibit neutrophil recruitment into inflamed tissue. The previous compounds ("leumedins") contained (alkoxycarbonyl)amino or benzoic acid moieties tethered to a fluorene ring. This functionality was replaced with simple structural elements. The new compounds were, in general, found to be more potent than the earlier series at inhibiting adherence of neutrophils to serum-coated wells or endothelial cells in vitro. Compound 9 was approximately 10-fold more potent than the previously reported FMOC-phenylalanine, of which it is an analogue. Similarly, compound 19 was superior in potency to its first generation progenitor, NPC 16570. The new compounds were shown to inhibit neutrophil adherence under conditions in which adherence is mediated by Mac-1 (CD11b/CD18) and LFA-1 (CD11a/CD18); they thus appear to target beta 2-integrins in their antiadhesion activity. These compounds provide a departure point for the further development of new cell adhesion inhibitors which should exhibit enhanced potency and a more selective mode of action.

[Value of Holter monitoring and the electrocardiographic exercise test in the diagnosis of silent ischemia after myocardial infarction]. / Wartosc badania holterowskiego i elektrokardiograficznej próby wysilkowej w diagnostyce bezbólowego niedokrwienia po przebytym zawale serca.

In 75 patients 24-hour ecg monitoring value was compared with exercise test in diagnostics of postinfarction silent ischemia. Results compatibility of both comparing examinations was 79% with regard to only painless ischemia (p less than 0.001) and 91% to both estimated painless or painful episodes (p less than 0.001). Painless ischemia was observed during ecg Holter monitoring and exercise test respectively in 39% and 35% of examined patients (NS) and/or with the angina respectively in 44% and 53% (p less than 0.01). 24-hour ecg monitoring and exercise test are of a comparable value in diagnosis of postinfarction silent ischemia, whereas in diagnostics of jointly estimated painless or painful ischemia the exercise test is a more sensitive examination than ecg Holter monitoring.