A Rapid and Convenient Synthesis of Derivatives of Imidazoles under Microwave Irradiation

An efficient and a quick microwave‐assisted synthesis of benzimidazoles and trisubstituted imidazoles was developed. Three benzimidazoles were obtained as a result of the condensation of 1,2‐phenylenediamine with carboxylic acids and acetoacetic ester without catalyst. A series of trisubstituted imidazoles were synthesized by condensation of benzil, aromatic aldehyde and ammonium acetate in the presence of glacial acetic acid.     

An optical surface plasmon resonance biosensor for determination of tetanus toxin

Surface plasmon resonance (SPR) has been successfully applied for the simple, rapid, and label-free assay of various biomolecules. This assay evaluates a novel wavelength modulation SPR biosensor for the detection of tetanus toxin. The wavelength modulation SPR biosensor is designed based on fixing the incident angle of light and measuring the reflected intensities in the resonance wavelength range spanning 400-800 nm simultaneously. Tetanus toxin (TeNT), one of the most potent toxins known, is synthesized as a 150 kDa single polypeptide chain. The SPR biosensor has been shown to be capable of directly detecting concentration of tetanus toxin as low as 0.028 Lf ml⁻¹. Under selected experimental conditions, the SPR biosensor has a good reproducibility, sensitivity and reversibility. The results illustrate how wavelength modulation SPR biosensor can be used to detect biomolecular interactions.     

Internal energy effects in collision induced dissociation spectra

The effect of the precursor ion internal energy on the branching ratios obtained from collision induced dissociation fragmentation patterns was examined for [NH₃]⁺ and [C₂H₄N]⁺. The ion internal energy was changed by varying both the chemical ionization reagent gas and the ion source pressure. Effects observed in the collision induced dissociation fragmentation patterns as a function of the ion source pressure are explained by the reaction exothermicities and by collisional deactivation of internally excited ions (at high pressure).     

SciFinder-guided rational design of fluorescent carbon dots for ratiometric monitoring intracellular pH fluctuations under heat shock

Intracellular pH plays a significant role in various biological processes, including cell proliferation, apoptosis, metabolism, enzyme activity and homeostasis. In this work, a novel design strategy for the preparation of pH responsive carbon dots (CDs-pH) for ratiometric intracellular imaging was reported. By using SciFinder database, fluorescent CDs-pH with the required pK_a value of 6.84 were rationally designed, which is vital important for precise sensing of intracellular pH. As a result, the synthesized CDs-pH demonstrated robust ability to test pH fluctuations within the physiological range of 5.4-7.4. The CDs-pH was further utilized for fluorescent ratiometric imaging of pH in living HeLa cells, effectively avoided the influence of autofluorescence from native cellular species. Moreover, real-time monitoring of intracellular pH fluctuation under heat shock was successfully realized. This SciFinder-guided design strategy is simple and flexible, which has a great potential to be used for the development of other types of CDs for various applications.     

钒、铬、锰磷桥络合物中31P NMR化学位移的研究

ISSIe山和W6flSChllh山子1960年首次用pdCI。和二苯基磷合成出黄色的二聚络合物，后被H。yieY＊确认为具有pRZ的桥式结构．此后一系列该类结构的化合物被合成并引起了广泛的兴趣．磷可以和两个甚至多个金属原子络合构成多核金属络合物，在催化反应中有重要应用．磷原子存在多种电子态，其3d空轨道也能参与成键．P乃1的NMR谱是研究含磷化合物立体结构的有力工具．P－31与其它核素之间的耦合常数以及P－31的化学位移对阐明化合物的立体构象以及电子结构具有重要作用．近年来，West饲用计算机神经网络技术预测P－：if的化学位移，但仅…     

Elucidating dominant factors of PO43-, Cd2+ and nitrobenzene removal by biochar: A comparative investigation based on distinguishable biochars

Four distinct biochars were employed to remove three typical pollutants, meanwhile, path analysis, a multi-statistical regression method, was performed to elucidate the dominant factors of biochar adsorption. This work can provide a new insight to prepare a targeted biochar as adsorbents.     

Bis(crown-6)calix[4]arene/Cs+ Coordination Chemistry in NPME Solution

NMR spectroscopy was used to show that the symmetry of the crown ether bis(C6) is increased by an increase of the alkali metal cation radius. The EXAFS spectrum demonstrates that a seven oxygen atom coordinated configuration is present in the bis(C6)/Cs⁺/NPME system, where NPME denotes o-nitrophenylmethyl ether. The seventh oxygen in this complex, besides the six crown ether oxygens of bis(C6), may come either from a H₂O molecule or an NO₃⁻ ion.     

Synthesis and Mesogenic Properties of Liquid Crystals Containing Terminal Cyclohexylmethanol,Cyclopentylmethanol, Cyclobutylmethanol and Cyclopropylmethanol Moiety

Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 .     

Cu(I) catalyst in DMF: an efficient catalytic system for the synthesis of furans from 2-(1-alkynyl)-2-alken-1-ones

The cyclization of 2-(1-alkynyl)-2-alken-1-ones 1 proceeded very smoothly in the presence of alcohols 2 with a catalytic amount of Cu(I)Br in DMF at 80 degrees C, leading to the formation of highly substituted furans 3. The catalytic system reported herein is easy to handle, compared to the previously known system wherein the reaction between 1 and 2 needed to use moisture sensitive gold(III) chloride.     

pH值对聚四氨基酞菁钴膜电化学和紫外光谱性质的影响

用循环伏安法在导电玻璃(ITO)和玻碳电极(GC)上制备了聚氨基酞菁钴(CoTAPc)修饰电极(CoTAPc/GC)。探讨了pH值对CoTAPc膜的光谱和电化学性质的影响，发现其氧化还原电位与pH值有线性关系，电催化活性也随酸度的增加而增加。CoTAPc膜的紫外吸收带变化与溶液pH值及在溶液中浸泡时间有关。