Search

In the reaction of ZnCl(2) with tacrine hydrochloride in water novel tetracoordinated (C(13)H(15)N(2))(2)[ZnCl(4)]-H(2)O complex was obtained and characterized by elemental analysis, molar conductivity and X-ray analysis. The complex crystallizes in the space group P-1 of the triclinic crystal system. The structure contains two crystallographically different molecules of protonated tacrine present as counter cations, the [ZnCl(4)](2-) complex anion and one water solvent molecule. The counter cations slightly differ in the puckering of the cyclohexene ring. The molecules of protonated tacrine are involved in different intermolecular hydrogen bonds. In the crystal, the hydrogen bonding generates a 3D assembly. In the crystal, pi center dot center dot center dot pi stacking interactions between the rings of protonated tacrine were evidenced. The [ZnCl(4)](2-) complex anion has a distorted tetrahedral geometry. Three out of the four Cl atoms are involved in intermolecular hydrogen bonding. The intermolecular H-bond interactions involving the Cl atoms affect the Zn-CI bond lengths., U reakciji ZnCl2 sa takrin-hidrohloridom u vodi, dobijen je novi tetrakoordinovani (C13H15N2)2[ZnCl4]?H2O kompleks koji je okarakterisan pomoću elementalne analize, molarne provodljivosti i rendgenske strukturne analize. Kompleks kristališe u prostornoj grupi P?1 trikliničnog kristalnog sistema. Struktura sadrži dva kristalografski različita molekula protonovanog takrina koji su prisutni kao kontra-katjoni, [ZnCl4]2 kompleksni anjon i molekul kristalne vode. Molekuli katjona se neznatno razlikuju u stepenu nabiranja cikloheksenovog prstena. Molekuli protonovanog takrina su uključeni u različite intermolekulske vodonične veze. Intermolekulsko vodonično vezivanje u kristalu generiše 3D molekulski skup pi...pi interakcije između prstenova protonovanog takrina su primećene u kristalu. [ZnCl4]2- ima distorgovanu tetraedarsku geometriju. Tri od četiri Cl atoma su uključena u intermolekulske vodonične veze. Intermolekulske vodonične interakcije koje uključuju Cl atome utiču na dužinu Zn-Cl veza.

In the reaction of ZnCl2 with tacrine hydrochloride in water novel tetracoordinated (C13H15N2)2[ZnCl4]?H2O complex was obtained and characterized by elemental analysis, molar conductivity and X-ray analysis. The complex crystallizes in the space group P?1 of the triclinic crystal system. The structure contains two crystallographically different molecules of protonated tacrine present as counter cations, the [ZnCl4]2- complex anion and one water solvent molecule. The counter cations slightly differ in the puckering of the cyclohexene ring. The molecules of protonated tacrine are involved in different intermolecular hydrogen bonds. In the crystal, the hydrogen bonding generates a 3D assembly. In the crystal, pi…pi stacking interactions between the rings of protonated tacrine were evidenced. The [ZnCl4]2- complex anion has a distorted tetrahedral geometry. Three out of the four Cl atoms are involved in intermolecular hydrogen bonding. The intermolecular H-bond interactions involving the Cl atoms affect the Zn-Cl bond lengths., U reakciji ZnCl2 sa takrin-hidrohloridom u vodi, dobijen je novi tetrakoordinovani (C13H15N2)2[ZnCl4]?H2O kompleks koji je okarakterisan pomoću elementalne analize, molarne provodljivosti i rendgenske strukturne analize. Kompleks kristališe u prostornoj grupi P?1 trikliničnog kristalnog sistema. Struktura sadrži dva kristalografski različita molekula protonovanog takrina koji su prisutni kao kontra-katjoni, [ZnCl4]2 kompleksni anjon i molekul kristalne vode. Molekuli katjona se neznatno razlikuju u stepenu nabiranja cikloheksenovog prstena. Molekuli protonovanog takrina su uključeni u različite intermolekulske vodonične veze. Intermolekulsko vodonično vezivanje u kristalu generiše 3D molekulski skup pi...pi interakcije između prstenova protonovanog takrina su primećene u kristalu. [ZnCl4]2- ima distorgovanu tetraedarsku geometriju. Tri od četiri Cl atoma su uključena u intermolekulske vodonične veze. Intermolekulske vodonične interakcije koje uključuju Cl atome utiču na dužinu Zn-Cl veza.

Thermal behavior of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand was investigated using the results of TG, DSC and DTG analysis obtained at different heating rates (2.5 to 30 A degrees C min(-1)), from room temperature to about 900 A degrees C. Mechanisms of complex degradation, as well as enthalpies of the degradation processes were determined. It is shown that thermal stability of investigated complexes correlates with their crystal structures, especially with the presence of crystallization and coordinated water molecules. The values of dehydration enthalpies are discussed and correlated with composition of the complexes. Kissinger's, Ozawa's, and Friedman's isoconversion methods were used for the determination of kinetic parameters: the pre-exponential factor A and the apparent activation energy E (a). For all three complexes and all steps of degradation, the values of kinetics parameters obtained by Kissinger's and Ozawa's methods are in good agreement. The results obtained by Friedman's method showed that some decomposition steps are simple and some others are complex ones.

In this paper the first complexes of M(2+) ions (M(2+) = Zn(2+), Cd(2+) and Co(2+)) with N-benzyloxycarbonyl-S-phenylalaninato ligand (1-3) are described. The new complexes were characterized by means of elemental analysis, IR and UV-vis spectroscopy, molar conductivity measurements and (1)H, (13)C and (15)N NMR spectroscopy (1D and 2D). The Co(II) complex adopts an octahedral geometry, and the Zn(II) and Cd(II) complexes adopt a tetrahedral one. For the first time, the antimicrobial activity of N-benzyloxycarbonyl-S-phenylalaninato ligand (N-Boc-S-phe) and the complexes 1-3 was investigated against Gram-positive: Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Bacillus subtilis and Gram-negative bacteria: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and two strains of the yeast Candida albicans. It was shown that the complexes were effective against most strains. The best activity was detected against the yeast C. albicans. (C) 2008 Elsevier Masson SAS. All rights reserved.

In this study, the first complexes of Zn(II) with the N-benzyloxycarbonyl-S-alaninato ligand (N-Boc-S-ala) were synthesized. The new complexes were characterized by elemental analysis, conductometric measurements, IR. (1)H-NMR, (13)C-NMR and 2D-NMR spectroscopy. On the basis of the experimental data, tetrahedral geometry of the Zn(II) complexes was proposed. A very good agreement between the NMR and DFT calculated data was obtained. Investigation of antimicrobial activity of the newly synthesized complexes was also performed. It was established that [Zn(N-Boc-S-ala)(2)] was selective and acts only on Candida aibicans., U ovom radu su sintetizovani prvi kompleksi Zn(II) sa N-benziloksikarbonil-S-alaninato ligandom (N-Boc-S-ala). Kompleksi su okarakterisani elementalnom analizom, konduktometrijskim merenjem, IR, 1H-NMR, 13C-NMR i 2D-NMR spektroskopijom. Tetraedarska geometrija Zn(II) kompleksa pretpostavljena je na osnovu eksperimentalnih podataka. Dobijeno je veoma dobro slaganje između NMR i DFT podataka. Ispitivana je antimikrobna aktivnost novosintetizovanih kompleksa. Ustanovljeno je da je [Zn(N-Boc-S-ala)2] kompleks selektivan i da deluje samo na gljivu Candida albicans.

For the first time, complexes of Zn(II), Cd(II) and Co(II) (1-3) with N-benzyloxycarbonylglycine have been synthesized and characterized. The complexes adopt tetrahedral, pentagonal-bipyramidal and octahedral geometry, respectively. The structure of the polymeric cadmium complex was resolved by single crystal X-ray analysis. The cadmium ion has a distorted pentagonal-bipyramidal coordination formed by two water molecules and two N-benzyloxycarbonylglycinato ligands (N-Boc) coordinated in different fashions, one as bidentate and the second connecting three cadmium atoms. In a rather complicated 2D supramolecular structure, the phenyl rings interact mutually exclusively by the CH center dot center dot center dot pi interactions. Investigation of the antimicrobial activity of the obtained complexes and N-benzyloxycarbonylglycine revealed that the ligand does not inhibit the growth of Candida albicans, whereas the newly synthesized complexes suppress the growth of this human fungal pathogen. (c) 2007 Elsevier B.V. All rights reserved.

A new binuclear Cu(II) complex with an (E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoato ligand (L) was successfully synthesized and characterized by elemental analysis and IR-spectroscopy. The structures of (E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoic acid (HL), and the corresponding (tetrakis)-mu-[(E)-4-(2,4-diisopropylphenyl)-4-oxo-2-butenoato]-bis(ethanol)-copper(II) complex, [Cu2L4(C2H5OH)(2)], were determined by single crystal X-ray analyses and are preliminarily discussed. This is the first complex of a transition metal with ligand L. as well as the first determined crystal structure of a metal complex with this type of ligand. Analysis of the magnetic susceptibility measurements of the isolated [Cu2L4(C2H5OH)(2)]center dot H2O complex shows the existence of a strong anti-ferromagnetic intra-dimer coupling, with an exchange integral value 2J of -260 cm(-1). (C) 2006 Elsevier B.V. All rights reserved.

Crystal structure of a novel cobalt(III) complex with antiulcer drug famotidine and ethylenediamine was determined. This is the second structure of a transition metal complex with famotidine resolved by a single crystal X-ray analysis, in which famotidine shows different mode of coordination than that observed in the other cases. Drug molecule is coordinated to metal ion as a tetradentate ligand through guanidine N6, thiazole N4, thioether S2 and terminal N3 atom. Two NH2 groups (N3H(2) and N6H(2)) are deprotonated and drug coordinates as dianion. In the asymmetric unit, one chloride anion and one water molecule were found to complete the complex stoichiometry. The structure of the complex is abundant in atoms, which can be involved in hydrogen bond formation either as hydrogen acceptors or hydrogen donors. Because of that, a great number of hydrogen bonds dominates the crystal packing. Beside the hydrogen bonds, there are two interesting noncovalent interactions: CH...pi and NH...pi within the famotidine anion, which stabilize the complex structure. The pi...pi stacking interactions between neighboring complex cations are also observed. Antibacterial and antifungal activity of famotidine and its newly synthesized complex against representative bacteria: Escherichia coli, Staphilococcus aureus and Micrococcus lysodeikticus and fungi: Aspergillus niger and Candida albicans were examined. The results indicate a higher selectivity of the famotidine-Co(III) complex, as well as better growth inhibitory activity (lower MIC values (MIC, minimal inhibitory concentration)) in comparison with the drug alone. (c) 2006 Elsevier Inc. All rights reserved.

Rotamer population of S-tyrosinato and S-phenylalaninato ligands side groups in diastereomers of (1,2-diaminoethane)bis(S-aminocarboxylato)cobalt(III) complexes is calculated by vicinal alpha and beta proton coupling constant analysis. The effect of noncovalent intra- and interligand interactions on the population of rotamers in D2O solution is discussed. It has been established that in all the complexes investigated the most abundant is rotamer t, in which aromatic voluminous moiety and carboxylic group are in an anti position. In almost all complexes the lowest content is of rotamer g, in which these two groups are in the nearest position. Relatively high population of rotamer b in complex 5 tyr, in spite of high steric hindrances, is due to intra- and interligand NH... pi interactions.

Two diastereomers of bis(1,3-diaminopropane)(S-phenylalaninato)cobalt(III) were prepared by reaction of S-phenylalanine with carbonatobis(1,3-diaminopropane)cobalt(III). The diastereomers were separated on an optically active Sephadex QAE column and their absolute configurations assigned by means of circular dichroism. In addition, H-1 NMR spectra of the diastereomers were analyzed in terms of the population of the three predominant rotamers of the coordinated S-phenylalaninato ligand. One out of 24 theoretically possible diastereomers of the dinuclear species di-mu-hydroxo-tetrakis(S-phenylalaninato)dicobalt(III) was obtained by direct synthesis and its absolute configuration deduced from CD spectra.

Four out of six theoretically possible isomers of the (1,3-diaminopropane)bis(S-tyrosinato)cobalt(III) complex, having the cis(O) configuration, were isolated, and the trans(O) isomer was only defined in the eluate. The isomers were separated on an optically active Sephadex QAE column. Geometrical and absolute configurations of the isomers were determined by electronic absorption, circular dichroic and H-1 NMR spectra. The effect of the aromatic side group of the coordinated S-tyrosinato ligand on the stereoselective formation of the obtained isomers was examined.