Synthesis of 14-aryl or alkyl- 14H-dibenzo[a,j]xanthenes promoted by Mg(HSO4)2

14-Aryl or alkyl-14H-dibenzo[a,j]xanthenes were prepared by condensation of 2-naphthol and aldehydes in the presence of Mg（HSO₄）₂ as an efficient,cheap,readily available and eco-friendly catalyst.This procedure has the advantages of high yields,easy work-up,short reaction times,and green conditions.     

Application of Dispersive Liquid�CLiquid Microextraction for the Analysis of Six Fungicides in Fruit Samples by GC�CECD

A novel approach for the determination of six fungicides (triadimefon, procymidone, hexaconazole, myclobutanil, diniconazole and iprodione) in fruit samples is presented. Analytes were extracted using the dispersive liquid?Cliquid microextraction technique and determined by GC?CECD. Parameters affecting the dispersive liquid?Cliquid microextraction performance, such as the kind and volume of extraction and dispersive solvents, extraction time and salt concentration, were studied and optimized. Under the optimum extraction conditions, the linearities of the method were obtained in the range of 0.5?C20.0 ??g kg^?1 for triadimefon, hexaconazole, diniconazole and procymidone, and 1.0?C40.0 ??g kg^?1 for myclobutanil and iprodione, with the correlation coefficients ranging from 0.9902 to 0.9995. The enrichment factors ranged from 685 to 820 and the extraction recoveries ranged from 81.3 to 98.4%. The relative standard deviations varied from 3.1 to 7.8%. The limits of detection of the method were in the range of 0.02?C0.12 ??g kg^?1. Results showed that the method we proposed can meet the requirements for the determination of target fungicides in fruit samples. Several compounds considered in this study were found in fruit samples.     

Quantum‐chemical,IR, NMR,and X‐ray diffraction studies on 2‐(4‐chlorophenyl)‐1‐methyl‐ 1H‐benzo[d]imidazole

The title molecule, 2‐(4‐chlorophenyl)‐1‐methyl‐1H‐benzo[d]imidazole (C₁₄H₁₁ClN₂), was prepared and characterized by ¹H NMR, ¹³C NMR, IR, and single‐crystal X‐ray diffraction. The molecular geometry, vibrational frequencies, and gauge including atomic orbital (GIAO) ¹H and ¹³C NMR chemical shift values of the title compound in the ground state have been calculated by using the Hartree‐Fock (HF) and density functional theory (DFT/B3LYP) method with 6‐31G(d) basis sets, and compared with the experimental data. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters, and the theoretical vibrational frequencies and GIAO ¹H and ¹³C NMR chemical shifts show good agreement with experimental values. The energetic behavior of the title compound in solvent media has been examined using B3LYP method with the 6‐31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, and nonlinear optical (NLO) properties of the title compound were investigated by theoretical calculations. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Double‐Oxygen‐Atom Transfer in Reactions of CemO2m+ (m=2–6) with C2H2

Cerium oxide cluster cations (Ce_mO_n⁺, m=2–16; n=2m, 2m±1 and 2m±2) are prepared by laser ablation and reacted with acetylene (C₂H₂) in a fast‐flow reactor. A time‐of‐flight mass spectrometer is used to detect the cluster distribution before and after the reactions. Reactions of stoichiometric Ce_mO_2m⁺ (m=2–6) with C₂H₂ produce Ce_mO_2m?2⁺ clusters, which indicates a “double‐oxygen‐atom transfer” reaction Ce_mO_2m⁺+C₂H₂→Ce_mO_2m?2⁺+(CHO)₂ (ethanedial). A single‐oxygen‐atom transfer reaction channel is also identified as Ce_mO_2m⁺+C₂H₂→Ce_mO_2m?1⁺+C₂H₂O (at least for m=2 and 3). Density functional theory calculations are performed to study reaction mechanisms of Ce₂O₄⁺+C₂H₂, and the calculated results confirm that both the single‐ and double‐oxygen‐atom transfer channels are thermodynamically and kinetically favourable.     

“Demonstration” vs. “designation” of measurement competence: the need to link accreditation to metrology

Formal acceptance of the results of chemical laboratories is increasingly organized through a) accreditation of measuring laboratories nationally and b) mutual recognition of accreditation internationally (through formal Multilateral Recognition Agreements, MRAs). However, real comparability of results of measurements is realized by using common (internationally agreed) measurement scales which make these results traceable to this scale, i.e. “traceable” to the same (internationally agreed) value of the unit of that scale. In addition, the criterion against which the evaluation is done, should be “external” to the measurement laboratories which are being evaluated. This is realized in IRMM’s International Measurement Evaluation Programme (IMEP) where evaluation is performed against values which are anchored using “metrology”, the science of measurement with its own rules, which offers a sound foundation for measurement in all scientific disciplines. It is argued in this paper that the demonstration of measurement capability against values on such scales provides a result-oriented rather than a procedure-oriented evaluation. Thus, competence can be “demonstrated” rather than just “designated” and this can be shown to both customers and regulators. It inspires more confidence.     

Acknowledgment

l-Nitroso-2-naphthol(HA)isahighlyselectivereagentforthespectrophotometricdeterminationofCo(III)i.Raoetal.havestUdiedtheequilibriumextractionbehaviorofmixedligandcomplexesoftrivalentSm,EuandDyionswithl-nitroso-2-naPhtholandtrioctylphosphineoxide',Dyrssenetal.haveexaminedthecomplexformationofTh(IV)withl-nitroso-2-naPhtholand2-nitroso-l-naPhthol',however,thereisnoreportfortheextractionmechanismoflanthanidesbeingattemptedwiththisreagent.Inrecentyears,ourlabhasdonesomeworkonthesolid-liquidext…     

面向乙烷/乙烯分离的金属有机框架膜的大规模计算筛选

相比于传统热驱动的低温蒸馏工艺, 基于金属有机框架(Metal-organic frameworks, MOFs)的膜分离是一种在技术和成本上可行的乙烷/乙烯分离替代方案. 为了加速MOF膜在这一气体分离领域中的应用, 本工作提出了两步筛选策略对12,020个真实MOF膜材料进行了大规模计算筛选, 其中MISQIQ04表现出最高的乙烷/乙烯膜选择系数(4.16)和较高的乙烷渗透率(4.35×10⁵ Barrer). 通过结构-性能关系分析, 可以发现窄孔径和低孔隙率的MOFs是选择性分离乙烷的最佳膜材料, 并且乙烷的选择性吸附对乙烷/乙烯膜分离过程起着主导作用. 与传统计算筛选方法相比, 本工作所提出的筛选策略降低了约87.1%的计算时间成本. 为了进一步缩短模拟时间, 本工作还开发了机器学习分类模型以实现对高性能MOF膜的快速预筛选并探讨了该模型的可移植性. 结果表明, 增加数据集的多样性有助于提高所开发模型的可移植性和泛化能力.     

偶氮型钯（Ⅱ）配合物液晶的合成与表征

偶氮型钯（Ⅱ）配合物液晶的合成与表征毕思玮，丁养军李桂芝（曲阜师范大学化学系曲阜２７３１６５）（曲阜师范大学生物系阜曲）关键词偶氮型，Ｐｄ（Ⅱ）．配合物，近晶型，热致型液晶Ｃｏｐｅ［１］报道了偶氮苯与铂、钯形成的配合物，其后Ｇｈｅｄｉｎｉ［２］合成了...     

Multi-NMR and fluorescence spectra study the effects of aluminum(III) on coenzyme NADH in aqueous solutions

The interactions of dihydronicotinamide adenine dinucleotide (NADH) with Al(III) in near neutral aqueous solutions were studied by means of multinuclear (31P, 27Al, 1H and 13C)-NMR and fluorescence spectra techniques. The results suggested that Al(III) interacts with NADH by occupying the binding sites of pyrophosphate oxygen atoms and locks the adenine moiety of coenzyme in an anti folded conformation Meanwhile, the weak attractive interactions ('association') may occur between Al(III) and the hydroxyl groups of ribose rings through the intramolecular hydrogen bonding. Furthermore, at biologically relevant pH and concentrations of Al(III) and NADH (pH 6.5, C(Al)=10(-6)-10(-5) M), Al(III) could increase the amount of folded forms of NADH, which will result in reducing the coenzyme NADH activity in hollow-dehydrogenases reaction systems. However, in the presence of possible competing organic acids such as citrate, oxalate and tartate, could detoxify these Al(III) toxic effect.     

Methane Decomposition over Ni/α-Al_2O_3 Promoted by La_2O_3 and CeO_2

The decomposition of methane on Ni/a-Al2O3 modified by La2O3 and CeO2 with different contents has been investigated and the ralationship between methane decomposition and removal of carbon by CO2 over these catalyst has also been studied by pulse-chromatography. The catalysts were characterized by TPR and XRD. It was shown that Ni/a-Al2O3 could be promoted by adding La2O3, and the carbon species produced over this catalyst was activated and eliminated by CO2. But CeO2 would suppress the decomposition of methane over Ni crystallite. Both La2O3 and CeO2 can inhibit aggregation of the Ni particles. Decomposition of methane over the Ni-based catalysts is structure sensitive to a certain extent.