基于苯乙烯腈结构的可逆力致变色化合物的合成及性能

合成了一种棒形的化合物4,4'-二(α-腈基-4-苯丙氧基苯乙烯)联苯(Ben-DCSB), 利用核磁共振(NMR)、质谱(EI-MS)、傅里叶变换红外光谱(FT-IR)和元素分析等对其进行了结构表征. 对Ben-DCSB重结晶粉末进行研磨后, 其发光颜色从蓝绿色变成黄绿色, 荧光量子效率(Φ_F)从初始的52.7%变为38.7%, 表明该化合物具有力致变色性质. 扫描电子显微镜(SEM)、X-射线衍射(XRD)和荧光寿命等测试结果显示, 这种现象是由于在外界环境刺激下改变了Ben-DCSB在聚集态下的分子堆积结构所造成的. 研磨后的样品暴露在溶剂蒸气(乙醇、二氯甲烷、四氢呋喃或丙酮)或100 ℃温度下放置2 min又能转换回初始状态的蓝绿色荧光, 表明化合物研磨后的样品具有气致和热致变色性能, 且展现出可逆变色性能. 对该化合物进行多次“力-溶剂蒸气刺激”和“力-热刺激”循环实验, 结果显示其具有很好的荧光可逆转换性能. 热分析结果显示化合物Ben-DCSB在194 ℃和212 ℃间存在向列相(纹影织构)的液晶态; 其热分解温度为362 ℃, 表明该化合物具有较好的热稳定性.     

Modified reverse microemulsion synthesis for iron oxide/silica core–shell colloidal particles

Iron oxide/silica core–shell colloidal particles were prepared by basic reverse microemulsion (RM) method and two modified RM methods. By basic RM method, maximum particle size obtained was mere 40 nm. For building photonic crystals working in the visible range, the colloidal particles must be larger than 100 nm. Thus two modified RM methods were used. By alcohol modified RM method, short chain alcohols were used as co-surfactant. The particle size rose to near 100 nm, but the core–shell structure was comparatively poor. By emulsifier pair modified RM method, the particle size leapt to over 200 nm and a narrow growth window was found favorable to enhance the stability and rigidity of the surfactants layers. The core–shell mechanism was also discussed and a new four-step mechanism was proposed.     

A bird nest-like manganese dioxide and its application as electrode in supercapacitors

A novel bird nest-like nanostructured MnO2(BNNS-MnO2) was prepared by a facile and cost-effective strategy. Their structures and morphologies were characterized by field emission scanning electron microscopy, transmission electron microscopy and powder X-ray diffraction. Capacitive behaviors were investigated by cyclic voltammetry and galvanostatic charge-discharge. The obtained nano-MnO2 possesses a well designed loose-assembled hierarchical nanoarchitecture with an appropriate crystallinity which gives rise to excellent performances as an electrode material for supercapacitors. A maximum specific capacitance of 917 F/g has been obtained at a current density of 5 mA/cm2 in 6 mol/L KOH aqueous solution, and a specific capacitance of 210 F/g has been maintained for 500 cycles. As the low cost of MnSO4 and KCr2O7 and the low reaction temperature, the present method avoids the requirements for complicated operations, time/energy-consuming and expensive reagents, and perhaps is ready for the industrialization of nano-MnO2 production.     

Structure-Activity Relationship, Cytotoxicity and Mode of Action of 2-Ester-substituted 1,5-Benzothiazepines as Potent Antifungal Agents

Our studies examined the structural features responsible for the antifungal activity of 2-ethoxycarbonyl-1,5- benzothiazepine （7a）. Three series of 1,5-benzothiazepine derivatives were synthesized and screened for their antifungal activity. The results suggested that the ethoxycarbonyl group at the 2 position and the imine moiety on the seven-membered ring are essential for activity. The most potent of the synthesized analogues （7a, 7b） were further studied by evaluating their cytotoxicity and mode of action （for 7a）. The results showed that compounds 7a and 7b were relatively safe for BV2 cells, but compound 7a interfered with Cryptococcus neoformans cell wall integrity by increasing the chitinase activity. Therefore, compound 7a was considered safe as an antifungal agent for animal cells.     

Simultaneous,real-time measurement of nitric oxide and oxygen dynamics during cardiac ischemia-reperfusion of the rat utilizing sol-gel-derived electrochemical microsensors

In this study, we simultaneously measured nitric oxide (NO) and oxygen (O₂) dynamics in the myocardium during myocardial ischemia-reperfusion (IR) utilizing sol-gel modified electrochemical NO and O₂ microsensors. In addition, we attempted to clarify the correlation between NO release in the ischemic period and O₂ restoration in the myocardium after reperfusion, comparing a control heart with a remote ischemic preconditioning (RIPC)-treated heart as an attractive strategy for myocardial protection. Rat hearts were randomly divided into two groups: a control group (n = 5) and an RIPC group (n = 5, with RIPC treatment). Myocardia that underwent RIPC treatment (182 ± 70 nM, p < 0.05) released more NO during the ischemic period than those of the control group (63 ± 41 nM). The restoration value of oxygen tension (pO₂) in the RIPC group significantly increased and was restored to pre-ischemic levels (92.6 ± 36.8%); however, the pO₂ of the control group did not increase throughout the reperfusion period (5.7 ± 7.5%, p = 0.001). Myocardial infarct size measurements revealed a significant decrease in cell death in the myocardium region of the RIPC group (41.44 ± 6.42%, p = 0.001) compared with the control group (60.05 ± 10.91%). As a result, we showed that the cardioprotective effect of RIPC could be attributed to endogenous NO production during the ischemic period, which subsequently promoted reoxygenation in post-ischemic myocardia during early reperfusion. Our results suggest that the promotion of endogenous formation during an ischemic episode might be helpful as a therapeutic strategy for protecting the myocardium from IR injury. Additionally, our NO and O₂ perm-selective microsensors could be utilized to evaluate the effect of drug or treatment.     

Higher alcohol synthesis over Cu-Fe composite oxides with high selectivity to C2+OH

Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2+OH and C6+OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity (GHSV) on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.     

Facile Fabrication of Multi‐targeted and Stable Biochemical SERS Sensors

The direct transfer of single‐crystalline Au nanowires (NWs) onto Au substrates was achieved by a simple attachment and detachment process. In the presence of a lubricant, Au NWs grown vertically on a sapphire substrate were efficiently moved to an Au substrate through van der Waals interactions. We demonstrate that the transferred Au NWs on the Au substrate can act as sensitive, reproducible, and long‐term‐stable surface‐enhanced Raman scattering (SERS) sensors by detecting human α‐thrombin as well as Pb²⁺ and Hg²⁺ ions. These three biochemically and/or environmentally important analytes were successfully detected with high sensitivity and selectivity by Au NW‐SERS sensors bound by a thrombin‐binding aptamer. Furthermore, the as‐prepared sensors remained in working order after being stored under ambient conditions at room temperature for 80 days. Because Au NWs can be routinely transferred onto Au substrates and because the resultant Au NW‐SERS sensors are highly stable and provide with high sensitivity and reproducibility of detection, these sensors hold potential for practical use in biochemical sensing.     

Rate and Product Studies in the Solvolyses of Two Cyclic Phosphorochloridate Esters

Kinetic and product studies of the solvolyses of acyclic phosphorochloridates are extended to two cyclic diesters, 2-chloro-1,3,2-dioxaphospholane-2-oxide (1) and 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane-2-oxide (2). Slightly faster solvolyses are observed for 1 than for the acyclic dimethyl phosphorochloridate (3), and 2 solvolyzes somewhat slower than 3. An extended Grunwald–Winstein equation treatment shows similar sensitivities to changes in solvent nucleophilicity and solvent ionizing power for 1, 2, and 3, and a concerted S_N2 attack is proposed in each case. Product studies for the solvolyses of 2 in aqueous alcohols are presented.