Optical sensor for carbon dioxide combining colorimetric change of a pH indicator and a reference luminescent dye

A new optical CO₂ sensor based on the luminescence intensity change of the europium(III) complex tris(thenoyltrifluoroacetonato) europium(III) dihydrate ([Eu(tta)₃]) caused by the absorption change of various pH indicators—thymol blue, phenol red, or cresol red—with CO₂ was developed and its CO₂ sensing properties were investigated. For all the CO₂ sensors using pH indicators the observed luminescence intensity from [Eu(tta)₃] at 613 nm increased with increasing CO₂ concentration. The linear calibration method based on the plot of (I₁₀₀–I₀)/(I–I₀) versus the inverse of CO₂ concentration was suggested, where I₀ and I₁₀₀ were luminescence intensities at 613 nm of the CO₂ sensor film in 100% nitrogen and 100% gaseous CO₂. In all cases the plots showed good linearity and the correlation factors of the plots, r², were 0.991 for thymol blue, 0.990 for phenol red, and 0.998 for cresol red. The slopes of the plots (A/B) for thymol blue, phenol red, and cresol red were 2.2, 5.2, and 9.0%, respectively. The response times of the CO₂ sensor film were 4.0 s for thymol blue, 4.4 s for phenol red, and 8.8 s for cresol red for switching from nitrogen to CO₂, and the recovery times of films were 36 s for thymol blue, 39.2 s for phenol red, and 56.6 s for cresol red for switching from CO₂ to nitrogen. The signal changes were fully reversible and hysteresis was not observed during the measurements. The highly sensitive CO₂ sensor was developed using thymol blue as an indicator for the CO₂-sensing probe.     

Syntheses and Characterizations of Novel One-dimensional Coordination Polymers Self-assembled from Co(NCS)_2 and Flexible Diester-bridged Pyridine-based Ligands

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Engineering cytochrome P-450s

Cytochrome P-450 isozymes represent a critical component of nature’s spectrum of detoxification catalysts that could be exploited for bioremediation. The ethanol-inducible human cytochrome P-450 2E1 serves as a model eukaryotic P-450 that complements the bacterial P-450 cam in dehalogenation and detoxification of environmental pollutants. We explored the construction of novel chimeric P-450s using cytochrome P-450 camC and 2E1 genes. For construction of chimera 1 (478 amino acids, 55.14 kDa), 145 amino acids from the N-terminus of P-450 2E1 protein (493 amino acids, 56.84 kDa) were replaced with 130 amino acids from the N-terminus of P-450 camC protein (415 amino acids, 46.66 kDa). In chimera 2 (525 amino acids, 60.24 kDa) the strategy involves replacement of 28 amino acids in the C-terminus of chimera 1 with 75 amino acids from the C-terminus of P-450 camC gene. Homology models of both the chimeric proteins were developed using SWISS-MODEL based on the known crystal structure of cytochrome P-450 camC, BM-3, 1DT6A, and 2C17A. The models indicated that the proposed heme-binding site was intact, which is inevitable for catalytic activity of cytochrome P-450s. The expression of chimera 1 and 2 genes in Escherichia coli DH5α was evident from light-pink cell pellets, protein band in sodium dodecyl sulfate polyacrylamide gel electrophoresis, and diagnostic carbon monoxide-difference spectra. Our studies show that strategies can be developed to exploit the natural diversity of the P-450 superfamily to generate chimeric biocatalysts that would provide new templates amenable to directed evolution.     

3-氨基-二氢噻吩-2-酮类Schiff碱的合成和生物活性研究

通过3-氨基-二氢噻吩-2-酮(DL-高半胱氨酸硫内酯)盐酸盐与取代苯甲醛反应, 得到3-氨基-二氢噻吩-2-酮类Schiff碱. 合成了9个化合物, 其中7个为首次报道的新Schiff碱类化合物. 化合物结构经IR, ¹H NMR和元素分析证实, 并对这些化合物进行了室内毒力测试, 结果表明此类化合物具有很好的杀菌、抑菌活性.     

4-hydroxy-2-quinolones. 114. Synthesis and structure of 6-R-5-hydroxy-2,4-dioxo-2,3,4,6-tetrahydrobenzo-[<Emphasis Type="Italic">c</Emphasis>][2,7]naphthyridine-1-carbonitriles

Hydration of ethyl 1-R-4-dicyanomethyl-2-oxo-1,2-dihydroquinoline-3-carboxylate gives the corresponding substituted cyanoacetamides which are readily and quantitatively cyclized to 6-R-5-hydroxy-2,4-dioxo-2,3,4,6-tetrahydrobenzo[c][2,7]naphthyridine-1-carbonitriles in the presence of aqueous base. For Communication 113 see [1]. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 726–735, May, 2007.     

A novel selective fluorescent chemosensor for Cu（Ⅱ）

A novel fluorescence enhancement Cu~(2 ) chemosensor derived from coumarin was prepared.Emission study found that it exhibits evident Cu~(2 )-amplified fluorescence prior to Co~(2 ),Pb~(2 ),Mg~(2 ),Mn~(2 ),Ni~(2 ),Zn~(2 ),Fe~(3 ),Ag~ and Cd~(2 ),and the largest emission enhancement factor is about 9 at a ratio of 2:1 (chemosensor 1/Cu~(2 )).     

Diastereoselectivity in the solid-phase synthesis of peptide heterocycle hybrids

Sixteen compounds containing the bicyclic moiety (3,8,10-trisubstituted 2,9-dioxo-5-thia-1,8-diazabicyclo[4.4.0]decane) were produced via solid-phase synthesis. Differing substitution at the 3- and 10-positions was used. These were analyzed using 2-D NMR techniques (ROESY) to determine the stereoselectivity of ring formation in the core heterocycle. Conformational analysis of the proposed transition state structure using Sybyl 6.8^® was used to rationalize the stereochemical outcome of ring formation.     

Lu2O3对球形Ni(OH)2高温充放电性能的影响

为了改善镍电极的高温充电效率，采用机械混合的方式将球形Ni(OH)2与不同比例的Lu2O3混合后制成粘结式镍正极。充放电测试、循环伏安和XRD等实验结果表明，掺杂Lu2O3后镍电极的析氧过电位明显提高，高温充电效率得到了很大改善，在充电后的电极中β-NiOOH生成；而且Lu2O3的掺杂比例对镍电极的高温性能在不同的充放电倍率下有不同程度的影响，3．5％是最好的掺杂比例，掺杂对高温小电流充电效率的改善作用要大于高温大电流充电。     

固体超强酸（SO4^2-／ZrO2）的异丁烷／1-丁烯烷基化反应性能和失活研究

研究了固体超强酸(SO4^2-／ZrO2)催化剂的酸性及异丁烷-1-丁烯烷基化反应性能，结果表明，固体超强酸的酸性与焙烧温度有关，适当提高焙烧温度有利于样品酸强度的提高，但焙烧温度过高会导致脱硫，使样品酸强度和酸量降低，固体超强酸的异丁烷／1-丁烯烷基化催化反应活性与其酸性相对应，酸性强，反应活性高，但催化剂的活性衰减很快，这是催化剂表面的快速积炭所致。     

Determination of thiol by high-performance liquid chromatography and fluorescence detection with 5-methyl-(2-(<Emphasis Type="Italic">m</Emphasis>-iodoacetylaminophenyl)benzoxazole

A new high-performance liquid chromatographic (HPLC) method for measuring low molecular weight (LMW) thiol-containing compounds, including cysteine (CysH), glutathione (GSH), N-acetylcysteine (Nac), penicillamine (PA), and 2-mercaptoethanol (2-ME), has been developed by using 5-methyl-(2-(m-iodoacetylaminophenyl)benzoxazole (MIPBO) as fluorescence-labeling reagent. The derivatization and separation conditions have been investigated in detail. Detection limits ranging from 3.5 to 15.0 fmol were achieved for the thiols investigated in a 16 min separation with detection wavelengths 310 and 375 nm for the excitation and emission, respectively. The utility of the proposed method has been validated by measuring CysH in human urine samples.