Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.1.2.42 (DTA)
1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two isomeric gold(I)-triphenylphosphine complexes with nitrogen-containing heterocycles, [Au(L)(PPh3) (HL = pyrazole (1), imidazole (2)) were isolated as colorless cubic crystals for 1 and colorless plate crystals for 2, respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These complexes were also fully characterized by complete elemental analyses, thermogravimetric/differential thermal analyses (TG/DTA) and FT-IR in the solid state and by solution NMR (31P, 1H and 13C) spectroscopy and molecular weight measurements in acetone solution. These complexes consisted of a monomeric 2-coordinate AuNP core both in the solid state and in solution. The molecular structures of 1 and 2 were compared with those of related gold(I) complexes, [Au(1,2,3-triz)(PPh3)] (3, Htriz = triazole), [Au(1,2,4-triz)(PPh3)]2 (4) as a dimer through a gold(I)-gold(I) bond in the solid state, and [Au(tetz)(PPh3)] (5, Htetz = tetrazole). Selective and effective antimicrobial activities against two gram-positive bacteria (B. subtilis, S. aureus) and modest activities against one yeast (C. albicans) found in these gold(I) complexes 1-4 are noteworthy, in contrast to poor activities observed in the corresponding silver(I) complexes.
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PMID:Synthesis, crystal structure and antimicrobial activities of two isomeric gold(I) complexes with nitrogen-containing heterocycle and triphenylphosphine ligands, [Au(L)(PPh3)] (HL = pyrazole and imidazole). 1085 18

Two water-soluble, silver(I) complexes showing a wide spectrum of effective antibacterial and antifungal activities, i.e., ([Ag(Hhis)].0.2EtOH)2 (1; H2his = L-histidine) and [Ag(Hpyrrld)]2 (3; H2pyrrld = (S)-(-)-2-pyrrolidone-5-carboxylic acid) were prepared. In aqueous solution 1 and 3 were present as dimers, whereas in the solid state they were polymers. Crystallization of 1 by slow evaporation and/or vapor diffusion gave water-insoluble crystals of [Ag(Hhis)]n (2) showing modest antimicrobial activities. The complex 1 in the solid state is a polymer formed by intermolecular hydrogen-bonding interactions between dimeric [Ag(Hhis)]2 cores, while 2 is a different polymer without a core complex. X-ray crystallography revealed that 2 was a left-handed helical polymer consisting of a bent, 2-coordinate silver(I) atom bonding to the Namino atom of one Hhis- ligand and the N pi atom of a different Hhis- ligand. Of particular note is the fact that Ocarboxyl atoms do not participate in the coordination. X-ray crystallography also revealed that 3 was a left-handed helical polymer formed by self-assembly of dimeric [Ag(Hpyrrld)]2 cores with an intramolecular metal(I)-metal(I) interaction (Ag-Ag distance, 2.9022(7) A). The FT-IR and the solid-state 13C and 15N NMR spectra showed that the dimeric core of 1 was formed through Ag-N bonds, while that of 3 was formed through Ag-O bonds. The molecular ions of 1 and 3 were detected by the positive-ion electrospray ionization (ESI) mass spectrometry. For 1-3, characterization by elemental analysis, TG/DTA, FT-IR, and variable-temperature solid-state 13C NMR and room-temperature 15N NMR measurements was performed, and for 1 and 3, that by solution molecular weight measurements and solution (109Ag, 1H, and 13C) NMR spectroscopies was also carried out. The antibacterial and antifungal activities of 1 and 3 were remarkable and comparable to those of the previous silver(I)-N-heterocycle complexes.
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PMID:Synthesis and characterization of water-soluble silver(I) complexes with L-histidine (H2his) and (S)-(-)-2-pyrrolidone-5-carboxylic acid (H2pyrrld) showing a wide spectrum of effective antibacterial and antifungal activities. Crystal structures of chiral helical polymers [Ag(Hhis)]n and ([Ag(Hpyrrld)]2)n in the solid state. 1119 68

Through two unequivalent oxygen donor atoms of the hinokitiol (Hhino; C10H12O2; 4-isopropyltropolone) ligand that showed noteworthy biological activities, the dimeric, silver(I)-oxygen bonding complex [Ag(hino)]2 1, the monomeric aluminium(III) complex [Al(hino)3].0.5H2O 4 and the cobalt(II) complex "[Co(hino)2]2.H2O" 6 were synthesized and characterized with elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR and solution (1H and 13C) NMR spectroscopy. The crystal structure of 1 was determined by Rietveld analysis based on X-ray powder diffraction (XPD) data and those of [Al(hino)3].MeOH 4a and [Co(hino)2(EtOH)]2 6a, being obtained as yellow block crystals and red platelet crystals, respectively, by crystallization of 4 and 6, were determined by single-crystal X-ray analysis. The antimicrobial activities of 1, 4 and 6, evaluated with minimum inhibitory concentration (MIC; microg ml(-1)), were compared with those of other metal complexes (M=Na, Li, Cs, Ca, V, Zn) with the hino- ligand. The antimicrobial activities observed in the alkali-metal salts strongly suggested that they were attributed to the effect of the anionic hino- species. The antimicrobial activities of 1 were significantly enhanced, whereas those of other metal complexes were suppressed, compared with those of the neutral Hhino and anionic hino- molecules. The antimicrobial activities observed in 1 were comparable with those of other recently found silver(I)-oxygen bonding complexes, the ligands of which had no activity. Thus, it is proposed that the antimicrobial activities of the silver(I)-oxygen bonding complexes are due to a direct interaction or complexation of the silver(I) ion with biological ligands such as protein, enzyme and membrane, and the coordinating ligands of the silver(I) complexes play the role of a carrier of the silver(I) ion to the biological system.
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PMID:Synthesis and structural characterization of silver(I), aluminium(III) and cobalt(II) complexes with 4-isopropyltropolone (hinokitiol) showing noteworthy biological activities. Action of silver(I)-oxygen bonding complexes on the antimicrobial activities. 1465 32

Water-soluble, relatively light-stable, chiral and achiral silver(I) complexes [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n)(R- and S-Hca =(1R,4S)- and (1S,4R)-4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylic acid, respectively) prepared from the reaction of Ag(2)O with chiral and racemic Hca in 1:2 and 1:4 molar ratios were characterized by elemental analysis, TG/DTA, FTIR, and solution ((1)H, (13)C and (109)Ag) and solid-state ((13)C) NMR spectroscopy. Crystallography revealed that unique 2(1) helical polymer and zigzag structures were formed on self-assembly of the dimeric units in the crystals of [[Ag(2)(S-ca)(2)]](n) and three [[Ag(2)(ca)(2)(Hca)(2)]](n). In the crystal of [[Ag(2)(S-ca)(2)]](n) two 2(1) helices and a loop were observed in the stair-like polymer structure, whereas zigzag and a loop were seen in the crystals of three [[Ag(2)(ca)(2)(Hca)(2)]](n). Carbon NMR spectra in the solid state and in D(2)O indicated that these polymeric structures were loosely bound and fast ligand-exchange reactions took place in aqueous solution. The complexes, [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n), showed a wide spectrum of effective antimicrobial activity as anticipated for weak silver(i)-O bonding complexes. Similar antimicrobial activity of [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n) against selected microorganisms suggested that ligand exchangeability played an important role as well as the coordination geometry of the silver(i) ion.
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PMID:Syntheses, structures and antimicrobial activities of water-soluble silver(I)-oxygen bonding complexes with chiral and racemic camphanic acid (Hca) ligands. 1551 Mar

Highly ordered silver sulfide nanorods conjugated with the Bovine Serum Albumin (BSA) protein have been successfully achieved at ambient temperature. Such a process is very simple and controllable, directly using silver nitrate and thioacetamide (TAA) as the reactants in the aqueous solution of BSA. The products have been characterized by XRD, HRTEM-SAED, SEM-EDS, TG-DTA, FT-IR, and CD spectroscopy. The results of the research show that the as-prepared Ag2S nanorods are monodispersed with sizes about 40 nm in diameter and 220 nm in length, and exhibit a high degree of crystallinity and good photoluminescence. Furthermore, an interesting mechanism is discussed for the formation of the Ag2S nanorods.
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PMID:Fabrication of protein-conjugated silver sulfide nanorods in the bovine serum albumin solution. 1672 64

A novel cetyltrimethyl ammonium silver bromide (CTASB) complex has been prepared simply through the reaction of silver nitrate with cetyltrimethyl ammonium bromide (CTAB) in aqueous solution at room temperature by controlling the concentration of CTAB and the molar ratio of CTAB to silver nitrate in the reaction solution, in which halogen in CTAB is used as surfactant counterion. The structure and thermal behavior of cetyltrimethyl ammonium silver bromide have been investigated by using X-ray diffraction (XRD), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), UV/vis spectroscopy, thermal analysis (TG-DTA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results show that the complex possesses a metastable layered structure. Upon heating the CTASB aqueous dispersion to above 80 degrees C, the structure change of the complex took place and CTAB-capped nanosized silver bromide particles further formed.
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PMID:A novel cetyltrimethyl ammonium silver bromide complex and silver bromide nanoparticles obtained by the surfactant counterion. 1718 88

The crystal structure of silver azide (AgN3) in its high-temperature (HT) modification was determined from X-ray powder diffraction data, recorded at T = 170 degrees C and was further refined by the Rietveld method. The structure is monoclinic (P21/c (No. 14), a = 6.0756(2) A, b = 6.1663(2) A, c = 6.5729(2) A, beta = 114.19(0) degrees, V = 224.62(14) A3, Z = 4) and consists of two-dimensional Ag and N containing layers in which the silver atoms are coordinated by four nitrogen atoms exhibiting a distorted square coordination environment. These sheets are linked together by weaker perpendicular Ag-N contacts, thus forming a 4 + 2 coordination geometry around the silver atoms. The phase transition has been characterized by DTA, DSC, and measurement of the density, as well as of the ionic conductivity. Both, the room-temperature and the HT phase are electrically insulating. This fact is getting support by DFT band structure calculations within the generalized gradient approximation, using the PBE functional. On the basis of the DFT band structure, the bonding characteristics of both phases are essentially the same. Finally, the implication of the existence of a low-symmetry HT-phase in a crystalline explosive concerning decomposition mechanisms is discussed.
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PMID:Crystal structure and chemical bonding of the high-temperature phase of AgN3. 1725 34

A novel neutral tetrameric silver(I) cluster [Ag(mtsc)](4) was obtained from reactions of a tridentate (4)N-morpholyl 2-acetylpyridine thiosemicarbazone ligand (N'-[1-(2-pyridyl)ethylidene] morpholine-4-carbothiohydrazide, Hmtsc) and silver(I) sources containing Ag-O bonds (Ag(2)O, Ag(OAc), silver(I) 2-pyrrolidone-5-carboxylate (infinity){[Ag(Hpyrrld)](2)}, silver(I) 5-oxo-2-tetrahydrofurancarboxylate (infinity){[Ag(othf)](2)}, and silver(I) complexes with camphanic acid (infinity){[Ag(ca)]} and (infinity){[Ag(ca)(Hca)]}). The cluster was characterized by elemental analysis, TG/DTA, FTIR and single-crystal X-ray analysis in the solid state. The solution properties of the complexes were investigated using solution molecular weight measurement, ESI-MS and solution ((1)H, (13)C and (31)P) NMR spectroscopy. The obtained cluster is a novel example of a light-stable Ag(I) cluster with a tridentate thiosemicarbazone ligand and the second report of a crystal structure of a thiosemicarbazone silver(I) complex. The reaction of the tetramer with a large excess of PPh(3) gave dimeric complexes, namely, [Ag(micro(S)-mtsc)(PPh(3))](2) and [(PPh(3))(2)Ag(micro(S)-mtsc)(2)Ag]. The chloroform solution of the tetrameric complex showed modest and effective activities against selected bacteria (Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa) and yeasts (Candida albicans and Saccharomyces cerevisiae), respectively, but it did not inhibit the growth of any selected microorganisms in a water-suspension system.
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PMID:Synthesis, reaction and structure of a highly light-stable silver(I) cluster with an Ag4S4N4 core having a tridentate 4N-morpholyl 2-acetylpyridine thiosemicarbazone ligand: use of water-soluble silver(I) carboxylates as a silver(I) source. 1770 Aug 27

Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I)/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 degrees C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp(2) carbon at the Raman spectrum of both samples.
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PMID:Silver nanoparticles and graphitic carbon through thermal decomposition of a silver/acetylenedicarboxylic salt. 2062 49

Ag-Si/TiO2 photocatalysts were synthesized in a nonaqueous system at 140 degrees C, and then annealed at different temperatures. The obtained photocatalysts were characterized by XRD, TEM, BET, TG-DTA, XPS, as well as UV-vis DRS. The results showed that All Ag-Si/TiO2 held an anatase phase and high thermal stability and the phase transformation from anatase to rutile was retarded to about 900 degrees C. The Ag-Si/TiO2 particles were highly mono-dispersed and the particles size became smaller compared to TiO2. Additionally, UV-vis light absorption shifted to visible region after Ag doping. Si weaved into the matrix of TiO2, while Ag dispersed on the surface of TiO2 particles. The visible light photocatalytic activity was evaluated by Rhodamine B (RhB) degradation in an aqueous solution under visible light irradiation. It was found that the photccatalytic activities of the obtained Ag-Si/TiO2 samples were all higher than those of pure TiO2 and Ag/TiO2, reaching the maximum at the Ag and Si content of 0.5 mol% and 20.0 mol%, respectively. The enhanced visible photocatalytic activity may be attributed to the simultaneous effects of silver and silicon co-doping.
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PMID:Ag-Si Co-doped TiO2 photocatalyst synthesized via a nonaqueous method. 2113 2


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