A new biomarker of protein oxidation degree and site using angiotensin as the target by MS

Hydroxyl radicals generated from Fenton reaction were used to damage the angiotensin. The oxidative damage degree and sites of peptides were measured by HPLC–MS and MS/MS. Experimental results proved that the oxidative damage degree increased with longer reaction time. The results also showed that the side chains of phenylalanine and tyrosine in angiotension can be attacked by hydroxyl radicals to form the oxidative products. A new strategy was established to monitor the oxidative degree and sites of peptides and laid the foundation for protein oxidation. This method can be used to investigate the mechanism of protein oxidative damage caused by oxidative stress which is induced by environmental pollutants and physiological activities. There will also be a wide application in the research of pathogenesis of some disease related to oxidative stress.     

A self-catenated network containing unprecedented 0D + 2D → 2D polycatenation array

Herein, we report a new acylamide ligand and its application in the construction of a metal-organic framework. The resultant acylamide metal-organic framework, namely [Zn(2)(L)(OH)(btc)](n) (1, L = N(1),N(4)-bis(pyridin-3-ylmethyl) naphthalene-1,4-dicarboxamide, H(3)btc = benzene-1,3,5-tricarboxylic acid), was obtained by hydrothermal synthesis. The outstanding structural feature of it is the 0D + 2D → 2D polycatenation array containing a self-catenated feature which has never previously been observed. To the best of our knowledge, the coexistence of self-catenation and polycatenation phenomena is highly exceptional.     

Fluorimetric detection of Mg2+ and DNA with 9-(alkoxyphenyl)benzo[b]quinolizinium derivatives

A benzo[b]quinolizinium-benzo-15-crown-5 ether conjugate 2a is presented that enables the fluorimetric detection of Mg(2+) and DNA by a significant light-up effect, along with a change of the emission wavelength with different analytes (Mg(2+): 495 nm; DNA: 550 nm). The mechanism of the excited-state deactivation of 2a was investigated by steady-state fluorescence spectroscopy in media of varied viscosity and compared with the photophysical properties of methoxyphenyl-substituted benzo[b]quinolizinium 2b (m,p-diOMe), 2c (m-OMe), and 2d (p-OMe) as reference compounds. Compounds 2a-c, which share the m-alkoxyphenyl substituent as the common feature, have low emission quantum yields (Φ(F) < 10(-2) in water) but exhibit a significant increase of their fluorescence intensity in viscous glycerol solutions. In contrast, the viscosity of the medium does not influence the emission properties of the parent phenyl-substituted benzo[b]quinolizinium 2e and of the p-methoxyphenyl-substituted derivative 2d. Based on these observations it is concluded that the excited-state deactivation in 2a-c is mainly due to the rotation of the m-alkoxy group about the C(ar)-O bond. The interaction of 2a-c with DNA or Mg(2+) ions was studied by spectrophotometric titrations and CD spectroscopy. Notably, the association of 2a or 2b with DNA or 2a with Mg(2+) ions induces a strong fluorescence enhancement (15- and 40-fold for DNA, 450-fold for Mg(2+)), which is rationalized by the suppression of the torsional-relaxation of the alkoxy-substituent in the excited state. Additionally, the cation-induced light-up effect of 2a is selective towards Mg(2+) ions as compared with other cations such as NH(4)(+), Li(+), Na(+), K(+) and Ba(2+).     

Layer-by-layer inkjet printing of fabricating reduced graphene-polyoxometalate composite film for chemical sensors

Graphene oxide (GO) nanosheets and polyoxometalate such as H(3)PW(12)O(40) (PTA) are prepared into a multilayer film via a layer-by-layer inkjet printing method. The GO/PTA composite thin film shows linear, uniform and regular layer-by-layer growth. Under UV-irradiation, a photoreduction reaction takes place in the film which converts GO to reduced GO (rGO) due to the photoreduction activity of polyoxometalate clusters. According to the cyclic voltammograms measurement, the rGO/PTA composite film displays good electrocatalytic activity for the oxidation of dopamine (DA). The oxidation peak current (I(pa)) increases gradually with increasing the dopamine concentration, which may be used in electrochemical biosensors.     

Novel Bisthienylethene Containing Ferrocenyl‐Substituted Naphthalimide: A Photo‐ and Redox Multi‐Addressable Molecular Switch

A new photochromic bisthienylethene system (BTE? NAFc) is reported in which the ferrocene unit (Fc) is incorporated into a naphthalimide chromophore as the central ethene bridging unit. The incorporated Fc unit in the photochromic system of BTE? NAFc has several effects on optical properties, such as fluorescence‐modulation through photoinduced electron transfer (PET), a decrease in the photochromic cyclization quantum yield, and a selective two‐step oxidation process. The ability to drive ring‐opening and ring‐closing reactions with a secondary redox‐modulation provides increased functionality to the photochromic system. Based on these meaningful photo‐ and redox‐modulation properties, five unprecedented multi‐addressable states (BTE? NAFc, BTE? NAFc⁺, c‐BTE? NAFc, c‐BTE? NAFc⁺, and BTE⁺? NAFc⁺) and gated photochromism are successfully obtained within the unimolecular BTE platform, thus providing deeper insight into photochromic systems as multifunctional outputs.     

木质素模型化合物在二氧化钛纳米管上光电氧化的动力学研究(英文)

本文用电化学方法制备了二氧化钛纳米管,并用扫描电子显微镜和X衍射对其形貌及组成进行了表征.进一步研究了木质素的两个模型化合物1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanediol(DMP)和3-hydroxy-1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanone(HDM)在二氧化钛纳米管上的光电氧化.在DMP的光电氧化过程中,一个新的紫外吸收峰出现在波长304 nm处.虽然中间体的形成速率随着浓度的增加而增加,却随着温度的增加而减少.尽管HDM和DMP在结构上有很小的差别,在氧化过程中DMP却呈现出很小的吸光度变化,表明HDM不易被光电氧化.量子化学计算结果也表明,DMP更容易被氧化,这个结果与光电氧化的结果相吻合.     

Borromean‐Entanglement‐Driven Assembly of Porous Molecular Architectures with Anion‐Modified Pore Space

A series of metal–organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1? Mn?OH^?, 2? Mn?SO₄^2?, 3? Mn?bdc^2?, 4? Eu?SO₄^2? (H₂BpybcCl₂=1,1′‐bis(4‐carboxybenzyl)‐4,4′‐bipyridinium dichloride, H₂bdc=1,4‐benzenedicarboxylic acid) have been obtained by a self‐assembly process. Single‐crystal X‐ray‐diffraction analysis revealed that all of these compounds contained the same n‐fold 2D→3D Borromean‐entangled topology with irregular butterfly‐like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non‐interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1? Mn?OH^? further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π‐conjugated structures.     

Synthesis,Photophysical and Electrochemical Properties of Amide‐Linked Phthalocyanine‐Fullerene Dyad

A new amide‐linked phthalocyanine‐fullerene dyad ZnPc‐C₆₀ was synthesized and characterized. The photophysical and electrochemical properties of the ZnPc‐C₆₀ dyad were investigated. The fluorescence spectrum and quantum yield in different solvents showed the occurrence of photoinduced electron transfer (PET) from the singlet excited ZnPc to C₆₀, which was further confirmed by nanosecond transient absorption spectra and cyclic voltammetry data. The free energy change for charge separation (ΔG_CS) was estimated to be exothermic with ?0.51 eV, which favored the formation of charge‐separation state. The PET from ZnPc to C₆₀ in ZnPc‐C₆₀ made the dyad exhibit stronger reverse saturable absorption performance compared with C₆₀ and the control sample in the Z‐scan experiments, which indicated the synergistic effect of two active moieties in the dyad.     

Diastereoselective Total Synthesis of (±)‐Schindilactone A,Part 2: Construction of the Fully Functionalized CDEFGH Ring System

The successful synthesis of the highly complex model compound ( 2 ) of the CEFGH ring system of schindilactone A ( 1 ) is described. Several synthetic methodologies were developed and applied to achieve this goal, including ring‐closing metathesis (RCM) and Co–thiourea‐catalyzed Pauson–Khand reactions. Furthermore, two independent approaches were developed for the construction of the GH ring of model compound 2 , the key steps of which included Pd–thiourea‐catalyzed carbonylative annulation, methylation, and sequential RCM/oxa‐Michael‐addition reactions. The chemistry developed herein has provided a greater understanding of the synthesis of schindilactone A ( 1 ) and its analogous compounds of the same family.