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61.
N-Bonded pentaamminecobalt(III) complexes of 2-cyanobenzamide, 2-cyanoacetamide, and fumaric, succinic, glutaric, and adipic amide-nitriles have been prepared. The kinetics of the base hydrolysis of (succinonitrile)pentaamminecobalt(III) have been measured: k(obsd) = k(OH) [OH(-)]; k(OH) = 1.23 x 10(3) {I = 1.00 M (NaCH(3)COO), 25 degrees C}. Amido-N-coordinated 2-cyanobenzamide cyclized in aqueous base, and it forms [(1-oxo-3-iminoisoindolino-endo-N)pentaamminecobalt(III). In aqueous acid it protonates on the exo-imine and solvolyzes (k(H) = 7.9 x 10(-)(5) s(-)(1)), forming the pentaammineaquacobalt(III) complex and 1-oxo-3-iminoisoindoline. In aqueous acid the amido-N complexes are protonated on the amide oxygen. The 2-cyanobenzamide species rearranges to form the nitrile-bonded linkage isomer in aqueous acid and also in Me(2)SO-d(6), while the succinic amide nitrile complex rearranges more slowly in aqueous acid to form solely the nitrile-bonded linkage isomer. The kinetics of the reaction were k(obsd) = f(k(H)[H(+)]/(K(a) + [H(+)])) where k(H) = 3.4 x 10(-)(4) M(-)(1) s(-)(1) and K(a) = 6.76 x 10(-)(2) M, pK(a) 1.2; pK(a) 1.3 (spectrophotometric) {I = 1.00 M (LiClO(4).3H(2)O), 25 degrees C}. In Me(2)SO-d(6) this amide-N complex reacts by three pathways: solvolysis, amide-N to -O isomerization, and amide-N to nitrile-bonded rearrangement (10%). The conjugate acid of the 2-cyanoacetamido-N complex reacted in both aqueous acid and acidified Me(2)SO-d(6) by solvolysis, amide N to O isomerization, and amide-N to nitrile-bonded rearrangement (17% in each solvent). The fumaric, glutaric, and adipic amide-nitrile complexes bonded through the amide nitrogen react only by solvolysis and amide-N to -O isomerization. Pentaamminecobalt(III) complexes of 2-cyanobenzamidine and succinic, glutaric, and adipic amidine-nitriles bonded through the amidine secondary nitrogen have been prepared. The 2-cyanobenzamidine complex undergoes rapid ligand cyclization to form the corresponding complex of 1,3-diiminoisoindoline bonded through the deprotonated endocyclic nitrogen. In aqueous acid the complex is protonated on one of the exo-imines, and this solvolyzes to form the pentaammineaquacobalt(III) complex and 1,3-diiminoisoindoline {k(H) = 1.7 x 10(-)(3) s(-)(1) (0.5 M HCl, 25 degrees C). Coordinated succinic amidine-nitrile also cyclizes in liquid ammonia to yield the complex of 2,5-diiminopyrrolidine bonded through the deprotonated endocyclic nitrogen. This is stable in aqueous base but solvolyzes rapidly (t(1/2) (s)) in aqueous acid to the aqua complex and succinimide; the latter is formed by hydrolysis of the free 2,5-diiminopyrrolidine. The dinuclear complex &mgr;-decaammine(succinonitrile)dicobalt(III) was synthesized; in aqueous base it forms &mgr;-(succinamido-N)decaamminecobalt(III). The dinuclear dinitrile complex reacts in liquid ammonia to form the corresponding succinic amidine-nitrile species which cyclizes rapidly to form &mgr;-decaammine(2,5-diiminopyrrolidino)cobalt(III) in which the ligand is bonded to cobalt(III) through the exo-imines.  相似文献   
62.
The global and local electrophilicity patterns of a series of 15 diazonium ions have been evaluated using the absolute scale of electrophilicity proposed by Parr et al. (J. Am. Chem. Soc. 1999, 121, 1922). The predicted global electrophilicity pattern of the whole series of diazonium ions correctly compares with the experimental electrophilicity recently determined for these charged electrophiles. The global electrophilicity is then projected into the different potential active sites of the molecular ions using the electrophilic Fukui function. The highest regional electrophilicity power is found at the terminal nitrogen atom of the arenediazonium ions, yet the highest positive charge is located on the nitrogen atom directly attached to the aromatic ring. This result is consistent with the observed reactivity displayed by diazonium ions toward substituted alkenes, thereby suggesting that the formation of the azocarbocation intermediate is mostly orbital rather than charge controlled.  相似文献   
63.
Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.  相似文献   
64.
The photocontrol of anthocyanin synthesis in dark-grown seedlings of tomato (Lycopersicon esculentum Mill.) has been studied in an aurea (au) mutant which is deficient in the labile type of phytochrome, a high pigment (hp) mutant which has the wild-type level of phytochrome and the double mutant au/hp , as well as the wild type. The hp mutant demonstrates phytochrome control of anthocyanin synthesis in response to a single red light (RL) pulse, whereas there is no measurable response in the wild type and au mutant. After pretreatment with 12 h blue light (BL) the phytochrome regulation of anthocyanin synthesis is 10-fold higher in the hp mutant than in the wild type, whilst no anthocyanin is detectable in the au mutant, thus suggesting that it is the labile pool of phytochrome which regulates anthocyanin synthesis. The au/hp double mutant exhibits a small (3% of that in the hp mutant) RL/far-red light (FR)-reversible regulation of anthocyanin synthesis following a BL pretreatment. It is proposed that the hp mutant is hypersensitive to the FR-absorbing form of phytochrome (Pfr) and that this (hypersensitivity) establishes response to the low level of Pfl. (below detection limits in phytochrome assays) in the au/hp double mutant.  相似文献   
65.
In this work a simple method was described for selective extraction of benzoic acid from landfill leachate samples. The samples were submitted to solid-phase extraction (SPE) with XAD-4 resin as the stationary phase and ion-exchange chromatography (IEC) using the ion-exchange resin Amberlyst A-27. The instrumental analysis was performed by gas chromatography with mass spectrometric detection (GC-MSD). Benzoic acid was isolated, identified and quantified. The extraction process is rapid, simple and of low cost. It was also environmental friendly, that is, it was used a minimum amounts of hazardous organic solvents and produced also minimum quantities of residues.  相似文献   
66.
The molecular structures of two lipophilic polyion aggregates derived from tetraphenyl imidodiphosphinate are described: [Na(crown ether)][MNa(2)[Ph(2)P(O)NP(O)Ph(2)](4)] with crown ether = 15-crown-5 for 1and benzo-15-crown-5 for (M = Na(+) for 1 and Na(H(2)O)(+) for 2).  相似文献   
67.
To meet growing needs for high throughput gene expression profiling, we established a new automated high throughput TaqMan RT-PCR method for quantitative mRNA expression analysis. In this method, the Allegro( trade mark ) (Zymark) system conducts all sample tracking and liquid handling steps, and ABI PRISM 7900 HT (Applied Biosystems) is used to conduct real-time determination of the C(t) value when amplification of PCR products is first detected and accumulation of inhibitory PCR products is unlikely to occur. The ABI PRISM 7900 HT Sequence Detection System features a real-time PCR instrument with 384-well-plate compatibility and robotic loading, and continuous wavelength detection, which enables the use of multiple fluorophores in a single reaction. The Allegro System offers an assembly line approach with a modular design that allows reconfiguration of the components to accommodate variations in the assay flow. In the present study, we have established and validated a new automated High Throughput (HT) TaqMan RT-PCR- based method for quantitative mRNA expression analysis. The data demonstrate that HT-Taqman PCR is a powerful tool that can be used for measuring low concentrations of mRNA, and is highly accurate, reproducible, and amenable to high throughput analysis. Results suggest that HT-TaqMan is a reliable method for the quantification of low-expression genes and a powerful tool with HT capability for target identification/validation, structure-activity relationship (SAR) study, compound selection for efficacy studies, and biomarker identification in drug discovery and development.  相似文献   
68.
Different techniques were selected for comprehensive characterization of seven samples of fly ashes collected from the electrostatic precipitator of the San Nicolás thermal power plant (Buenos Aires, Argentina). Particle size was measured using laser based particle size analyzer. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the mineral phase present in the matrix consisting basically of aluminosilicates and large amounts of amorphous material. The predominant crystalline phases were mullite and quartz. Major and minors elements (Al, Ca, Cl, Fe, K, Mg, Na, S, Si and Ti) were detected by energy dispersive X-ray analysis (EDAX). Trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, V and Zn) content was quantified by inductively coupled plasma optical emission spectrometry (ICP OES). Different acid mixtures and digestion procedures were compared for subsequent ICP OES measurements of the dissolved samples. The digestion procedures used were: i) a mixture of FH + HNO3 + HClO4 (open system digestion); ii) a mixture of FH + HNO3 (MW-assisted digestion); iii) a mixture of HF and aqua regia (MW-assisted digestion). Instrumental neutron activation analysis (INAA) was employed for the determination of As, Ba, Co, Cr, Ce, Cs, Eu, Fe, Gd, Hf, La, Lu, Rb, Sb, Sc, Sm, Ta, Tb, Th, U and Yb. The validation of the procedure was performed by the analysis of two certified materials namely, i) NIST 1633b, coal fly ash and ii) GBW07105, rock. Mean elements content spanned from 41870 μg g− 1 for Fe to 1.14 μg g− 1 for Lu. The study showed that Fe (41870 μg g− 1) ? V (1137 μg g− 1) > Ni (269 μg g− 1) > Mn (169 μg g− 1) are the main components. An enrichment, with respect to crustal average, in many elements was observed especially for As, V and Sb that deserve particular interest from the environmental and human health point of view.  相似文献   
69.
The capacity for anaerobic decolorization of a sulfonated azo dye, Congo Red, by a strain of a sulfate-reducing bacterium was evaluated. After optimizing the growth rate of the bacteria on a simple carbon source and terminal electron acceptor pair, lactate and sulfate, respectively, the effect of the dye concentration on their growth rate was analyzed. The decolorization rate was affected by the dye concentration in the growth medium. The azo-bond cleavage mechanism of reductive decolorization with the formation of benzidine was consistent with the results, as this metabolite was identified by high-performance liquid chromatography. Several fractions of the culture medium, including lysed cell extracts, were examined for the capacity to reduce the azo dye. This reduction capacity was found in the culture medium in which the cells had previously grown. The results showed that the mechanism of reductive decolorization of this sulfonated azo dye was extracellular and nonenzymatic, consistent with the production of sulfide anion by the microorganisms while growing on lactate and sulfate. The sulfide anions were the cause of the reduction leading to the disappearance of color in the medium. To increase the rate of decolorization, the presence of ferrous ion was also necessary together with the lactate and sulfate substrates.  相似文献   
70.
A series of chiral diphenyl-substituted macrocyclic polyether-diester ligands have been prepared from the chiral diphenyl-substituted tetraethylene glycol. Enantiomeric recogntion by the chiral diphenyl-substituted pyridino-diester-18-crown-6 compound ( 7 ) was studied by temperature dependent 1H NMR spectroscopy in deuteriodichloromethane. This ligand exhibited chiral recognition when complexed with the hydrogen per-chlorate salts of (R)- and (S)-α-(1-naphthyl)ethylamine and (R)- and (S)-methyl phenylalaninate.  相似文献   
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