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11.
This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described. 相似文献
12.
Four new Schiff base functionalized 1,2,3-triazolylidene nickel complexes, [Ni-(L1NHC)2](PF6)2; 3, [Ni-(L2NHC)2](PF6)2; 4, [Ni-(L3NHC)](PF6)2; 7 and [Ni-(L4NHC)](PF6)2; 8, (where L1NHC = (E)-3-methyl-1-propyl-4-(2-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenyl)-1H-1,2,3-triazol-3-ium hexafluorophosphate(V), 1, L2NHC = (E)-3-methyl-4-(2-((phenethylimino)methyl)phenyl)-1-propyl-1H-1,2,3-triazol-3-ium hexafluorophosphate(V), 2, L3NHC = 4,4′-(((1E)-(ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2,1-phenylene))bis(3-methyl-1-propyl-1H-1,2,3-triazol-3-ium) hexafluorophosphate(V), 5, and L4NHC = 4,4′-(((1E)-(butane-1,4-diylbis(azanylylidene))bis(methanylylidene))bis(2,1-phenylene))bis(3-methyl-1-propyl-1H-1,2,3-triazol-3-ium) hexafluorophosphate(V), 6), were synthesised and characterised by a variety of spectroscopic methods. Square planar geometry was proposed for all the nickel complexes. The catalytic potential of the complexes was explored in the oxidation of styrene to benzaldehyde, using hydrogen peroxide as a green oxidant in the presence of acetonitrile at 80 °C. All complexes showed good catalytic activity with high selectivity to benzaldehyde. Complex 3 gave a conversion of 88% and a selectivity of 70% to benzaldehyde in 6 h. However, complexes 4 and 7–8 gave lower conversions of 48–74% but with higher (up to 90%) selectivity to benzaldehyde. Results from kinetics studies determined the activation energy for the catalytic oxidation reaction as 65 ± 3 kJ/mol, first order in catalyst and fractional order in the oxidant. Results from UV-visible and CV studies of the catalytic activity of the Ni-triazolylidene complexes on styrene oxidation did not indicate any clear possibility of generation of a Ni(II) to Ni(III) catalytic cycle. 相似文献
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15.
《Journal of Coordination Chemistry》2012,65(11):1788-1796
A new monobasic bidentate ON donor Schiff base PS–LH2 (where PS–LH2 = polystyrene-anchored Schiff base obtained by condensation of chloromethylated polystyrene (containing 1.17 mmol of chlorine per gram of resin cross-linked with 2% divinylbenzene), 2-hydroxy-1-naphaldehyde and 4-aminosalicylic acid has been synthesized. PS–LH2 reacts with metal complexes to form polystyrene-anchored complexes: PS–LHM(CH3Coo) · DMF (where M = Cu, Zn, Cd, UO2), PS–LHZr(OH)2(CH3Coo) · 2DMF, PS–LHFeCl2 · 2DMF, PS–LHM′(CH3Coo) · 3DMF (where M′ = Mn and Ni) and PS–LHMoo2(acac), where acacH = acetylacetone. The polystyrene-anchored complexes have been characterized by elemental analysis, IR, ESR and magnetic susceptibility measurements. The per cent reaction conversion of PS–LH2 to polystyrene supported coordination compounds lies between 30–95. Shifts of the azomethine ν(C=N) and phenolic ν(C–O) stretches are indicative of ON donor behaviour of the polystyrene-anchored ligands. The complexes, PS–LHCu(CH3Coo) · DMF, PS–LHFecl2 · 2DMF, PS–LHMn(CH3Coo) · 3DMF and PS–LHNi(CH3Coo) · 3DMF are paramagnetic, while PS–LHZn(CH3Coo) · DMF, PS–LHCd(CH3COO) · DMF, PS–LHUo2(CH3Coo) · DMF, PS–LHZr(OH)2(CH3COO) · 2DMF and PS–LHMoO2(acac) are diamagnetic. The copper(II) complex exhibits a square planar structure, zinc(II) and cadmium(II) complexes have tetrahedral structures, nickel(II), manganese(II), iron(III), dioxomolybdenum(VI) and dioxouranium(VI) complexes have octahedral structure and zirconium(IV) complex is pentagonal bipyramidal. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(10):1812-1820
A Fe(III) complex with Cl counter ion based on a branched Schiff base has been synthesized and studied. The compound was produced by the reaction of the Schiff base with FeCl3 at room temperature in benzene–ethanol. The complex is symmetric, i.e., bis-chelate, with an octahedral coordination of Fe. The compound revealed phase transitions of the “solid–solid” type. The complex displayed a temperature-induced spin transition (S?=?1/2???5/2) which was detected by EPR. 相似文献
17.
《Journal of Coordination Chemistry》2012,65(2):315-322
Two structurally similar trinuclear complexes, [Cu(Cu(μ-Cl)2L1)2] (1) and [Cu(Cu(μ-Cl)2L2)2] (2) (HL1 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol, HL2 = 1-[(2-piperidin-1ylethylimino)methyl]naphthalen-2-ol), have been synthesized and structurally characterized. Both complexes are bridged trinuclear compounds. The central Cu in each complex is in an octahedral environment with two phenolate and four bridging chlorides. The symmetry-related terminal Cu in each complex is square pyramidal with one phenolate oxygen, one imine nitrogen and one amine nitrogen of the Schiff-base ligand, one Cl? in the basal plane, and one bridging Cl? in the apical position. The complexes and Schiff bases were tested in vitro for their antibacterial activities. 相似文献
18.
《Journal of Coordination Chemistry》2012,65(6):952-964
N,N′-bis(salicylidene)thiosemicarbazide Schiff base has been synthesized by the reaction of thiosemicarbazide with salicylaldehyde and then reacted with formaldehyde to generate phenolic groups, resulting in the formation of Schiff-base monomeric ligand. It was further incorporated with transition metals, Mn+2, Co+2, Ni+2, Cu+2, and Zn+2, to form Schiff-base metal complex, which was then polymerized with toluene 2,4-diisocyanate to form metal-chelated polyurethanes. Monomeric ligand, its metal complexes, and its metal polychelates were characterized and compared by elemental analysis, FT-IR, 1H NMR, thermal, and biocidal activities to evaluate the enhancement in physical and chemical properties on coordination with metal and on polymerization. SEM images of ligand and polymer metal complexes showed changes in surface morphology, while electronic spectra of polymer metal complexes were used to predict the geometry. Antimicrobial activities were determined by using agar-diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans, and Aspergillus flavus (yeast). The polymeric ligand had varied antibacterial and antifungal activities, enhanced after chelation and polymerization. Comparative results show that coordination of metal to the ligand enhances its physical and chemical properties which were meliorated on polymerization. 相似文献
19.
《Journal of Coordination Chemistry》2012,65(22):3659-3665
Some Schiff-base complexes of UO2(II) ion derived from 2-hydroxyacetophenone and aliphatic diamines under reflux conditions have been synthesized. The resulting ligands and their complexes have been characterized by elemental analyses (C, H, N), infrared, 1H NMR, 13C NMR and mass spectra. In these efficient reactions, Schiff-base complexes with important applications in analytical and organic chemistry are prepared. 相似文献
20.
Aishakhanam H. Pathan Ganesh N. Naik Raghavendra P. Bakale Shrinath S. Machakanur Kalagouda B. Gudasi 《应用有机金属化学》2012,26(3):148-155
A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of a tridentate hydrazone were prepared and characterized by various spectro‐analytical techniques and magnetic moment studies. The complexes were found to be monomeric and non‐electrolytes. The copper complex is electrochemically active in the applied potential range. The compounds synthesized in the present study have shown promising antiproliferative activity when screened using the in vitro method against two human cancer cell lines: HeLa and HepG2. The Escherichia coli DNA‐binding properties of all the compounds were investigated with UV–visible absorption spectrophotometric titrations, viscosity measurements, DNA melting experiments and gel electrophoreses measurements. The compounds were demonstrated to act as DNA intercalators with appreciable DNA‐binding constant values. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献