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1.
Solution equilibrium studies on Cu(II)-, Ni(II)- and Zn(II)-N-Me-β-Alaninehydroxamic acid (N-Me-β-Alaha), -N-Me-α-alaninehydroxamic acid (N-Me-α-Alaha), -Imidazole-4-carbohydroxamic acid (Im-4-Cha), -N-Me-imidazole-4-carbohydroxamic acid (N-Me-Im-4-Cha) and -Imidazole-4-acetohydroxamic acid (Im-4-Aha) systems have been performed by pH-potentiometry, UV–Vis spectrophotometry, EPR, CD, ESI-MS and 1H NMR methods. According to the results: (i) the amino-N atoms are more basic in N-Me-α-Alaha and N-Me-β-Alaha than the hydroxamate function, but the trend is just the opposite between the imidazole-N(3) and hydroxamate. (ii) The metal ion anchor is always the hydroxamate part in the amino acid derivatives, while it is always the imidazole-N(3) in the studied imidazolehydroxamic acids. (iii) The three studied N-Me derivatives do not form metallacrowns. Only hydroxamate type chelate is formed with N-Me-β-Alaha, but with N-Me-α-Alaha a new type of coordination mode (via amino-N and hydroxamate-O) also exists. N-Me-Im-4-Cha also forms a dinuclear complex, [M2L3], with Cu(II) and Ni(II) (but not with Zn(II)). In this complex, one of the three ligands might bridge the two metal ions (five-membered hydroxamate-(O,O) plus five-membered (Nim, Ocarb) bridging bis-chelating mode), while each of the additional two ligands binds to one metal. (iv) The two studied N–H derivatives, having dissociable proton on the hydroxamic-N, are able to form metallacrown species. A pentanuclear complex, [M5L4H−4], is exclusively formed above pH 4 between Cu(II) and Im-4-Aha. Interestingly, this 12-metallacrown-4 type complex, although together with various mononuclear binding isomers, appears also with Ni(II) and Zn(II). Unfortunately, the complexes of Im-4-Cha are not soluble in water at physiological pH at all. 相似文献
2.
Edit Csapó Dániel Sebők Julia Makrai Babić Filip Šupljika Gabriella Bohus Imre Dékány 《Journal of Dispersion Science and Technology》2014,35(6):815-825
Gold nanoparticles reduced by sodium citrate (d ~ 10 nm) and purchased gold colloid particles (d ~ 500 nm) were examined and compared. The properties of both gold particles and their biofunctionalized derivatives with L-cysteine and L-glutathione were studied in the presence of sodium nitrate. The structural investigations indicated an aggregated inner structure. The isoelectric points of pure gold, citrate reduced gold, and functionalized gold were measured and compared. The low isoelectric point of pure gold/water interface was explained by considering the distribution and accumulation of H+ and OH? ions within the interfacial water layer, being more pronounced for OH? ions. 相似文献
3.
An Abnormal N‐Heterocyclic Carbene–Carbon Dioxide Adduct from Imidazolium Acetate Ionic Liquids: The Importance of Basicity 下载免费PDF全文
Zsolt Kelemen Barbara Péter‐Szabó Dr. Edit Székely Dr. Oldamur Hollóczki Dzmitry S. Firaha Prof. Dr. Barbara Kirchner Dr. József Nagy Prof. Dr. László Nyulászi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):13002-13008
In the reaction of 1‐ethyl‐3‐methylimidazolium acetate [C2C1Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N‐heterocyclic carbene (NHC)–CO2 adduct I , but also isomeric aNHC‐CO2 adducts II and III were obtained. The abnormal NHC‐CO2 adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC‐CO2 adduct I , which can then be converted in the presence of the excess of CO2 to the more stable 2‐deprotonated anionic abnormal NHC–CO2 adduct via the anionic imidazolium‐2,4‐dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation. 相似文献
4.
The vesicle system consisting of 80 mol% dipalmitoylphosphatidylethanolamine (DPPE) and 20 mol% dipalmitoylphosphatidylglycerol (DPPG) undergoes to structural changes caused by various concentrations of Salmonella minnesota R595 lipopolysaccharide (LPS). The phenomenon was investigated by methods applying small- and wide-angle X-ray scattering (SAXS and WAXS), calorimetry (DSC) and freeze-fracture. In the low LPS concentration regime (investigated at 0.02 LPS/DPPE–DPPG molar ratio) a phase separation was observed. Two kind of domains are formed which are rich and poor in DPPE and in these domains cubic and lamellar structures are present, respectively. Increasing the LPS concentration up to 0.1 LPS/DPPE–DPPG molar ratio the phase separation is more expressed and the temperature domains of the phase transitions are more different. Increasing the temperature chain melting of the lamellar phase occurs first and destruction of the cubic phase is observed later. At high LPS concentration (equimolar ratio of LPS/DPPE–DPPG), where this amphiphilic molecule cannot be considered any more a guest molecule, the cubic structure dominates the phase behaviour of the LPS molecules. 相似文献
5.
Specific Design of Titanium(IV) Phenolato Chelates Yields Stable and Accessible,Effective and Selective Anticancer Agents 下载免费PDF全文
Sigalit Meker Dr. Ori Braitbard Dr. Matthew D. Hall Prof. Jacob Hochman Prof. Edit Y. Tshuva 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):9986-9995
Octahedral titanium(IV) complexes of phenolato hexadentate ligands were developed and showed very high stability for days in water solutions. In vitro cytotoxicity studies showed that, whereas tetrakis(phenolato) systems are generally of low activity presumably due to inaccessibility, smaller bis(phenolato)bis(alkoxo) complexes feature high anticancer activity and accessibility even without formulations, also toward a cisplatin‐resistant cell line. An all‐aliphatic control complex was unstable and inactive. A leading phenolato complex also revealed: 1) high durability in fully aqueous solutions; accordingly, negligible loss of activity after preincubation for three days in medium or in serum; 2) maximal cellular accumulation and induction of apoptosis following 24–48 h of administration; 3) reduced impact on noncancerous fibroblast cells; 4) in vivo efficacy toward lymphoma cells in murine model; 5) high activity in NCI‐60 panel, with average GI50 of 4.6±2 μm . This newly developed family of TiIV complexes is thus of great potential for anticancer therapy. 相似文献
6.
A study was made on permanganate oxidation of olefinic and acetylenic alcohols in aqueous alkali media. Deprotonation constants of alcohols can be calculated from the kinetic data. The rate constant of alkoxide group oxidation exceeded that of the unsaturated bond. For oxidation of the alcoholic group a mechanism based on hydride ion transfer is proposed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 561–567, 2002 相似文献
7.
8.
The purpose of this note is to compare the power of U-statistics based change-point tests and U-statistics based sequential tests. The theorems describe the large sample behaviour of these tests under local alternatives, and their analysis shows that sequential tests are more powerful under certain assumptions. 相似文献
9.
Edit Rmi Antal Rockenbauer Lszl Korecz Istvn Rusznk Andrs Víg 《Radiation Physics and Chemistry》1999,55(5-6):555-558
Light-induced stable free radicals (SFRs) were detected in azoreactive dyed cotton fabrics. Extremely slow photofading occurred under exposure to light of relatively long wavelength. The rate of photofading and SFR formation depend on the structure of the dye. Some of them show little drop in the rate of fading with the increasing wavelength, whereas others show nearly negligible changes under incident light of relatively long wavelength. In general a high rate of photofading was found when the SFR concentration was low. 相似文献
10.
Edit Csapó Péter Buglyó Nóra Veronika Nagy M. Amélia Santos Alma Corona Etelka Farkas 《Polyhedron》2010
Two histidinehydroxamic acid derivatives (N-methyl-histidinehydroxamic acid, N-Me-Hisha and Z-histidinehydroxamic acid, Z-Hisha) have been synthesized and their complexation with Cu2+-, Ni2+- and Zn2+-ions has been studied by using pH-potentiometric, UV–Vis, CD, 1H NMR, EPR and ESI-MS methods. Both of the two new derivatives contain one donor atom less compared to the histidinehydroxamic acid (Hisha). In the case of N-Me-Hisha the hydroxamate-N as donor is eliminated, while the coordination of the amino-N of Z-Hisha is not possible at all. 相似文献