Two Uranyl Complexes with Pyromellitic Acid. A Heterometallic Complex with U=O–CuII Interaction

Two uranyl complexes based on pyromellitic acid were hydrothermally synthesized, and their X‐ray single‐crystal diffraction structures were determined. Complex [UO₂(Hbtec)]^–(Himd)⁺ · H₂O ( 1 ) (H₄btec = pyromellitic acid, imd = imidazole), is an ionic complex, which shows a typical (4, 4) topological structure in the space. A heterometallic complex, UO₂Cu(btec)(phen) ( 2 ) (phen = 1,10‐phenanthroline) results from the reaction of uranyl nitrate and copper(II) bromide with pyromellitic acid. The structure of complex 2 revealed that the chains of UO₇ and CuO₃N₂ units were connected to each other through the carboxyl groups and U=O–Cu interactions to create a two‐dimensional framework.     

Syntheses,Structures, and Luminescent Properties of d10 Coordination Polymers with 2‐(4‐Carboxyphenyl)‐imidazo[4, 5‐f]‐1, 10‐phenanthroline and 1, 3‐Benzenedicarboxylate Derivatives

Four Zn^II/Cd^II coordination polymers (CPs) based on 2‐(4‐carboxy‐phenyl)imidazo[4, 5‐f]‐1, 10‐phenanthroline (HNCP) and different derivatives of 5‐R‐1, 3‐benzenedicarboxylate (5‐R‐1, 3‐BDC) (R = NO₂, H, OH), [Zn(HNCP)(5‐NO₂‐1, 3‐BDC)]_n ( 1 ), [Cd(HNCP)(5‐NO₂‐1, 3‐BDC)]_n ( 2 ), [Zn(HNCP)(1, 3‐BDC)(H₂O)₂]_n ( 3 ), and {[Zn(HNCP)(5‐OH‐1, 3‐BDC)(H₂O) · H₂O}_n ( 4 ) were synthesized under hydrothermal conditions. Compounds 1 – 4 were determined by elemental analyses, IR spectroscopy, and single‐crystal and powder X‐ray diffraction. Compounds 1 and 2 are isomorphous, presenting a 4‐connected uninodal (4, 4)‐sql 2D framework with threefold interpenetration, which are further extended into the three‐dimensional (3D) supramolecular architecture through π ··· π stacking interactions between the aryl rings of 5‐NO₂‐1, 3‐BDC. Compared to compound 1 , 3 is obtained by using different reaction temperatures and metal‐ligand ratios, generating a 3D framework with –ABAB– fashion via π ··· π stacking interactions. Compound 4 is a 1D chain, which is further extended into a 3D supramolecular net by hydrogen bonds and π ··· π stacking interactions. The thermogravimetric and fluorescence properties of 1 – 4 were also explored.     

Theoretical prediction of the host–guest interactions between novel photoresponsive nanorings and C60: A strategy for facile encapsulation and release of fullerene

A series of photoresponsive‐group‐containing nanorings hosts with 12～14 Å in diameter is designed by introducing different number of azo groups as the structural composition units. And the host–guest interactions between fullerene C₆₀ and those nanoring hosts were investigated theoretically at M06‐2X/6‐31G(d)//M06‐L/MIDI! and wB97X‐D/6‐31G(d) levels. Analysis on geometrical characteristics and host–guest binding energies revealed that the designed nanoring molecule (labeled as 7 ) which is composed by seven azo groups and seven phenyls is the most feasible host for encapsulation of C₆₀ guest among all candidates. Moreover, inferring from the simulated UV‐vis‐NIR spectroscopy, the C₆₀ guest could be facilely released from the cavity of the host 7 via configuration transformation between trans‐form and cis‐form of the host under the 563 nm photoirradiation. Additionally, the frontier orbital features, weak interaction regions, infrared, and NMR spectra of the C₆₀@7 host–guest complex have also been investigated theoretically. © 2015 Wiley Periodicals, Inc.     

Enzyme-regulated the changes of pH values for assembling a colorimetric and multistage interconnection logic network with multiple readouts

Based on enzymatic reactions-triggered changes of pH values and biocomputing, a novel and multistage interconnection biological network with multiple easy-detectable signal outputs has been developed. Compared with traditional chemical computing, the enzyme-based biological system could overcome the interference between reactions or the incompatibility of individual computing gates and offer a unique opportunity to assemble multicomponent/multifunctional logic circuitries. Our system included four enzyme inputs: β-galactosidase (β-gal), glucose oxidase (GOx), esterase (Est) and urease (Ur). With the assistance of two signal transducers (gold nanoparticles and acid–base indicators) or pH meter, the outputs of the biological network could be conveniently read by the naked eyes. In contrast to current methods, the approach present here could realize cost-effective, label-free and colorimetric logic operations without complicated instrument. By designing a series of Boolean logic operations, we could logically make judgment of the compositions of the samples on the basis of visual output signals. Our work offered a promising paradigm for future biological computing technology and might be highly useful in future intelligent diagnostics, prodrug activation, smart drug delivery, process control, and electronic applications.     

Relative Stability of Multiple Bonds between Germanium and Stibium. A Theoretical Study

Substituent effects on the potential energy surface of XGeSb (X=H, Li, Na, BeH, MgH, BH₂, AlH₂, CH₃, SiH₃, NH₂, PH₂, OH, SH, F, and Cl) were investigated by using B3LYP/Def2‐TZVP, B3PW91/Def2‐ TZVPP CCSD (T)//B3LYP/Def2‐TZVP methods. The isomers include structures with formal double (Ge=SbX) and triple (Xge=Sb) bonds to germanium‐stibium, so a direct comparison of these types of species is possible. Our model calculations indicate that electropositively substituted Ge=SbX species are thermodynamically and kinetically more stable than their isomeric Xge=Sb molecules. Moreover, the theoretical findings suggest that only the organic substitutions (such as CH₃) can make triply bonded Xge=Sb molecule more stable than the doubly bonded Ge=SbX species.     

Bioactive Trichothecenes Produced by the Myrothecium sp. QB‐1

Three new simple trichothecenes, 15‐acetyltrichoverrol B ( 3 ), 13′‐acetyltrichoverrin B ( 5 ), and 6′‐dehydroxytrichoverrin B ( 6 ), along with five known trichothecenes trichodermadienediol B ( 1 ), trichoverrol B ( 2 ), trichoverrin B ( 4 ), and roridins A ( 7 ) and D ( 8 ), have been isolated from the liquid culture of Myrothecium roridum (strain no. QB‐1). The structures of the new compounds were established by comprehensive analysis of 1D‐ and 2D‐NMR data. All the compounds were evaluated for antifungal activity, only compounds 7 and 8 showed significant antifungal activity against the tested fungi (MIC ranged from 10 to 5 μg/ml).     

Cobalt(II)‐Catalyzed C?H Alkynylation/Annulation with Terminal Alkynes: Selective Access to 3‐Methyleneisoindolin‐1‐one

A highly efficient cobalt(II)‐catalyzed alkynylation/annulation of terminal alkynes assisted by an N,O‐bidentate directing group is described. This protocol is characterized by wide substrate scope utilizing cheap cobalt catalysts, and offers a new approach to 3‐methyleneisoindolin‐1‐one, which can be converted into an oxadiazine salt in one step. Moreover, the directing group could be removed in three steps.     

Thermo-sensitive poly(DEGMMA-co-MEA) microgels: Synthesis,characterization and interfacial interaction with adsorbed protein layer

The novel microgels, poly[di(ethylene glycol) methyl ether methacrylate-co-2-methoxyethyl acrylate] poly(DEGMMA-co-MEA) microgels, were synthesized. The poly(DEGMMA-co-MEA) microgels were thermo-sensitive and exhibited a volume phase transitive temperature(VPTT) of 14–22 ?C. The incorporation of hydrophobic comonomer MEA shifted the VPTT of poly(DEGMMA-co-MEA) microgels to lower temperatures. The interfacial interaction of poly(DEGMMA-co-MEA) microgels and three model proteins, namely fibrinogen, bovine serum albumin and lysozyme, was investigated by quartz crystal microbalance(QCM). An injection sequence of "microgel-after-protein" was then established for the real-time study of the interaction of proteins and the microgels at their swollen and collapsed states by using QCM technique. The results indicated that the interfacial interaction of poly(DEGMMA-co-MEA) microgels and adsorbed protein layers was mainly determined by the electrostatic interaction. Because poly(DEGMMA-co-MEA) microgels were negatively charged in Tris-HCl buffer solution(p H = 7.4), the microgels did not adsorb on negatively charged fibrinogen and bovine serum albumin layers but strongly adsorbed on positively charged lysozyme layer. Stronger interaction between lysozyme and the microgels at collapsed state(i.e. at 37 ?C) was observed. Furthermore, the incorporation of MEA might weaken the interaction between poly(DEGMMA-co-MEA) microgels and proteins.     

氢氧混合气体爆轰波的真实化学反应模型数值模拟

采用高精度的ENO格式和基于基元化学反应的真实化学反应模型求解氢氧混合气体一维爆轰波的精细结构。采用直接起爆方法得到稳定传播的爆轰波 ,计算的爆轰波阵面参数和实验相当符合。对爆轰波反应区化学反应的研究表明 ,参与反应的不同组分具有不同类型的变化特征。网格尺寸影响的研究表明 ,计算结果的精度随着网格尺寸的增加而增加 ,并能保持较好的收敛性。移动网格研究结果表明 ,网格运动速度和爆轰速度接近时 ,两者的相互作用对计算结果产生一定影响。     

Selective Probing of Gaseous Ammonia Using Red‐Emitting Carbon Dots Based on an Interfacial Response Mechanism

Solid‐state fluorescence sensing is one of the most appealing detection techniques because of its simplicity and convenience in practical operation. Herein, we report the development of a red‐emitting carbon dots (RCDs)‐based material as a solid‐state fluorescence sensor for the selective probing of gaseous ammonia. The RCDs were prepared by a low‐cost, one‐step carbonization method using sugar cane bagasse as the carbon precursor. The pristine RCDs were then directly coated on polyvinylidene fluoride membrane to produce a new fluorescence sensor capable of selectively distinguishing toxic gaseous ammonia from other analyte vapors through sensitive fluorescence quenching with a low detection limit. More importantly, the interfacial response mechanism occurring on the surface of the RCDs has been studied by X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, and Raman measurements. The results indicate that fluorescence quenching in the RCDs might result from ammonia‐induced Michael addition through insertion of N into the C?C group and deprotonation of the carboxyl group. To the best of our knowledge, this is the first report that provides clear insight into the mechanism of surface chemistry on CDs in the solid state.