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61.
Malgorzata Frik Dr. Josefina Jiménez Ismael Gracia Prof. Larry R. Falvello Sarya Abi‐Habib Karina Suriel Prof. Theodore R. Muth Prof. María Contel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3659-3674
The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au2(mes)2(μ‐LL)] (LL=dppe: 1,2‐bis(diphenylphosphano)ethane 1 a , and water‐soluble dppy: 1,2‐bis(di‐3‐pyridylphosphano)ethane 1 b ) with Ag+ and Cu+ lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au2M(μ‐mes)2(μ‐LL)][A] (M=Ag, A=ClO4?, LL=dppe 2 a , dppy 2 b ; M=Ag, A=SO3CF3?, LL=dppe 3 a , dppy 3 b ; M=Cu, A=PF6?, LL=dppe 4 a , dppy 4 b ). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au2(mes)2(μ‐dppy)] ( 1 b ) and [Au2Ag(μ‐mes)2(μ‐dppe)][SO3CF3] ( 3 a ) were determined by a single‐crystal X‐ray diffraction study. 3 a in solid state is not a cyclic trinuclear Au2Ag derivative but it gives an open polymeric structure instead, with the {Au2(μ‐dppe)} fragments “linked” by {Ag(μ‐mes)2} units. The very short distances of 2.7559(6) Å (Au? Ag) and 2.9229(8) Å (Au? Au) are indicative of gold–silver (metallophilic) and aurophilic interactions. A systematic study of their luminescence properties revealed that all compounds are brightly luminescent in solid state, at room temperature (RT) and at 77 K, or in frozen DMSO solutions with lifetimes in the microsecond range and probably due to the self‐aggregation of [Au2M(μ‐mes)2(μ‐LL)]+ units (M=Ag or Cu; LL=dppe or dppy) into an extended chain structure, through Au? Au and/or Au? M metallophilic interactions, as that observed for 3 a . In solid state the heterometallic Au2M complexes with dppe ( 2 a – 4 a ) show a shift of emission maxima (from ca. 430 to the range of 520‐540 nm) as compared to the parent dinuclear organometallic product 1 a while the complexes with dppy ( 2 b–4 b ) display a more moderate shift (505 for 1 b to a max of 563 nm for 4 b ). More importantly, compound [Au2Ag(μ‐mes)2(μ‐dppy)]ClO4 ( 2 b ) resulted luminescent in diluted DMSO solution at room temperature. Previously reported compound [Au2Cl2(μ‐LL)] (LL dppy 5 b ) was also studied for comparative purposes. The antimicrobial activity of 1–5 and Ag[A] (A=ClO4?, SO3CF3?) against Gram‐positive and Gram‐negative bacteria and yeast was evaluated. Most tested compounds displayed moderate to high antibacterial activity while heteronuclear Au2M derivatives with dppe ( 2 a – 4 a ) were the more active (minimum inhibitory concentration 10 to 1 μg mL?1). Compounds containing silver were ten times more active to Gram‐negative bacteria than the parent dinuclear compound 1 a or silver salts. Au2Ag compounds with dppy ( 2 b , 3 b ) were also potent against fungi. 相似文献
62.
F Matthaei S Heidorn K Boom C Bertram A Safiei J Henzl K Morgenstern 《J Phys Condens Matter》2012,24(35):354006
The submonolayer growth of NaCl bilayer high-rectangular shaped islands on Ag(111) is investigated at around room temperature by using low temperature scanning tunneling microscopy. The growth at the step edges is preferred. Two kinds of islands are observed. They either grow with their non-polar edge at the step edge of Ag(111) or the islands overgrow in a carpet-like mode with the polar direction parallel to the edge. In the latter case, the Ag step is rearranged and considerable, while the NaCl layer is bent. This study clarifies the nature of the interaction of an alkali halide nanostructure with a metal step edge. 相似文献
63.
The DNA base thymine is deposited at 100?K on Cu(111) and investigated and manipulated by low-temperature scanning tunneling microscopy at 5?K. At submonolayer coverage paired rows are observed. At monolayer coverage a hexagonal commensurate self-assembled layer with the methyl group pointing away from the surface forms. A reversible local manipulation of molecules within the self-assembled layer is demonstrated. This manipulation is interpreted as an out-of-plane relaxation of molecules within the layer induced by the change of the adsorption geometry of individual molecules between two meta-stable orientations. A positive field of 2-4?V leads to this local change in the molecular arrangement, while a field larger than 4?V restores the original geometry. 相似文献
64.
We advance a perspective outcome of tempered α-stable processes used in modeling of anomalous diffusion, a physical mechanism underlying the non-Debye relaxations. The tempered processes are characterized by a heavy tail truncation in time and have finite moments, but they also save some useful features of a purely skewed α-stable process. Due to these features, the relaxation phenomena get a transient character being shown in their asymptotic behavior. From the stochastic subordination scenario of the tempered anomalous diffusion we derive relaxation functions with independent low- and high-frequency exponents falling in the range (0, 1]. Those functions can be used to model all types of experimentally observed two-power-law relaxation patterns. 相似文献
65.
Fiametti KG Ustra MK de Oliveira D Corazza ML Furigo A Vladimir Oliveira J 《Ultrasonics sonochemistry》2012,19(3):440-451
This work reports experimental kinetic data of solvent-free glycerolysis of olive oil using a commercial immobilized lipase (Novozym 435) under the influence of ultrasound irradiation. The experiments were performed in a mechanically stirred reactor under ultrasound irradiation, evaluating the effects of temperature (50-70 °C), enzyme concentration (2.5-10 wt%) and glycerol to oil molar ratio (0.8:1-3:1). Results show that ultrasound-assisted lipase-catalyzed glycerolysis might be a potential alternative route to conventional methods, as high contents of reaction products, especially monoglycerides, were achieved at mild irradiation power supply (∼130 W) and temperature, in a relatively short reaction time (2 h) and low enzyme content (7.5 wt%). To completeness, two simplified kinetic modeling approaches, based on the ordered-sequential bi bi mechanism and reaction stoichiometry, were employed to represent the experimental data, thus allowing a better understanding of the reaction kinetics. 相似文献
66.
Nguyen HN Cee VJ Deak HL Du B Faber KP Gunaydin H Hodous BL Hollis SL Krolikowski PH Olivieri PR Patel VF Romero K Schenkel LB Geuns-Meyer SD 《The Journal of organic chemistry》2012,77(8):3887-3906
Herein we describe a general three-step synthesis of 4-substituted chlorophthalazines in good overall yields. In the key step, N,N-dimethylaminophthalimide (8a) directs the selective monoaddition of alkyl, aryl, and heteroaryl organometallic reagents to afford 3-substituted 3-hydroxyisoindolinones 9b, 9i-9am. Many of these hydroxyisoindolinones are converted to chlorophthalazines 1b-1v via reaction with hydrazine, followed by chlorination with POCl(3). We have also discovered two novel transformations of 3-vinyl- and 3-alkynyl-3-hydroxyisoindolinones. Addition of vinyl organometallic reagents to N,N-dimethylaminophthalimide (8a) provided dihydrobenzoazepinediones 15a-15c via the proposed ring expansion of 3-vinyl-3-hydroxyisoindolinone intermediates. 3-Alkynyl-3-hydroxyisoindolinones react with hydrazine and substituted hydrazines to afford 2-pyrazolyl benzoic acids 16a-16d and 2-pyrazolyl benzohydrazides 17a-17g rather than the expected alkynyl phthalazinones. 相似文献
67.
Karina González‐Segura Paulina Cañete‐Rosales Rodrigo del Rio Claudia Yáñez Nancy F. Ferreyra Gustavo A. Rivas Soledad Bollo 《Electroanalysis》2012,24(12):2317-2323
The electrochemical response of a glassy carbon electrode modified with carbon nanotubes (CNT) dispersed in two solvents, water and DMF, and two polymers, chitosan and Nafion is reported. The films were homogeneous when the dispersing agent was water or DMF. In the case of polymers, the surfaces present areas with different density of CNTs. A more sensitive electrochemical response was obtained when CNTs are dispersed in the solvents. In the case of CNT dispersed with polymers, the nature of the polymer demonstrated to be a critical parameter not only for dispersing the nanotubes but also for the electrochemical activity of the resulting electrodes. 相似文献
68.
This work presents the application of membrane technology for the fabrication of stationary phase for CEC columns using the technique based on phase inversion of polymer solution. A blend of polyimide P84 and sulphonated poly(ether ether ketone was processed via immersion precipitation dry‐wet spinning into small‐bore porous fiber. The morphology, zeta potential, and performance of the porous structure in the CEC separation were investigated. Noncharged molecules (as markers of the electroosmotic flow) and small organic compounds were injected into the column, driven under the application of voltage, and detected on the electropherogram. The proof of concept of applying porous membrane structure as stationary phase for CEC was shown and possible optimization to improve efficiency and selectivity was suggested. 相似文献
69.
M. Teresa S. R. Gomes Karina S. Tavares João A. B. P. Oliveira 《Analytical and bioanalytical chemistry》2001,369(7-8):616-619
A new sensor for calcium based on a piezoelectric quartz crystal is presented. The selectivity depends on the ratio lipophilic salt/ionophore of the composition of the coating of the quartz crystal. A crystal coated with a THF solution of PVC (34.5% w/w), DOS (62.1% w/w) and 10,19-bis[(octadecylcarbamoyl) methoxyacetyl]-1,4,7,13,16-pentaoxa-10,19-diaza cycloheneicosane (3.4% w/w) and a salt/ionophore molar proportion of 60%, corresponding to a frequency decrease of the dry crystal of 6.0 kHz, showed a detection limit to calcium of 2.2 mg/L. Both a standard calcium chloride solution and a commercially balanced salt solution for tissue culture were analyzed subsequent to ion chromatographic separation. The results obtained with the sensor developed were compared with those obtained with a conductivity detector. Although the results from both detectors agreed for the standard solution, only the quartz crystal sensor was able to give reliable results for the tissue culture solution. 相似文献
70.
Sahar?Alhogail Ghadeer?A.?R.?Y.?Suaifan Sergio?Bizzarro Wendy?E.?Kaman Floris?J.?Bikker Karina?Weber Dana?Cialla-May Jürgen?Popp Mohammed?ZourobEmail author 《Mikrochimica acta》2018,185(2):149
Porphyromonas gingivalis (P. gingivalis) is a pathogen causing periodontitis. A rapid assay is described for the diagnosis of periodontal infections related to P. gingivalis. The method is making use of gingipains, a group of P. gingivalis specific proteases as a detection biomarker. Magnetic-nanobeads were labeled with gingipain-specific peptide substrates and immobilized on a gold biosensing platform via gold-thiol linkage. As a result of this, the color of the gold layer turns black. Upon cleavage of the immobilized substrates by gingipains, the magnetic-nanobeads-peptide fragments were attracted by a magnet so that the golden surface color becomes visible again. This assay is highly sensitive and specific. It is capable of detecting as little as 49 CFU·mL?1 of P. gingivalis within 30 s. Examination of periodontitis patients and healthy control saliva samples showed the potential of the assay. The simplicity and rapidity of the assay makes it an effective point-of-care device. 相似文献