水溶性杯[4]芳烃衍生物与稀土铽[Ⅲ]离子形成配合物的荧光行为

近年来 ,杯芳烃衍生物与稀土离子配合物的发光因在荧光免疫分析和发光材料的开发上具有潜在的应用价值而引起了人们极大的兴趣 [1～ 3] .人们已经合成了一系列带有羧基、吡啶和羰基等官能团的杯 [4]芳烃衍生物 ,并在非水溶剂中能敏化稀土离子发光 ,但在水溶液中效果并不理想 [4～ 7] .本文报道Scheme1　 The structure of calix[4]arenesulfonate水溶性杯 [4]芳烃衍生物与稀土铽 [ ]离子形成配合物的荧光行为 .结果表明 ,乙酸修饰的磺化杯 [4]芳烃 L2 在水溶液中不仅能对 Tb3+进行有效的能量传递 ,形成高效的能量传递发光体系 ,而且也能与…     

有机磷酸萃取剂的结构及其立体效应

结构为R(R’)P(O)OH的有机磷酸萃取剂的立体效应对其选择性有重要影响 ,但至今尚缺乏公认的表征有机磷酸立体效应的结构参数。本文以两个取代基与磷原子之间的夹角∠RPR’表征立体效应。在八面体构型中 ,配位于中心原子的两个有机磷酸的两对取代基大致在同一平面之中 ,夹角∠RPR’越大 ,相互作用越强 ,位阻越大。而在四面体构型中 ,两对取代基在互为正交的两个平面中 ,位阻小得多。实验表明 ,有机磷酸萃取钴时 ,八面体的钴萃合物转化为四面体的热力学参数与∠RPR’的变化趋势一致     

Synergistical assembly of multiwalled carbon nanotubes/polyaniline network for dye‐sensitized solar cells

In this study, an aniline (ANI) solution containing well‐dispersed multiwall carbon nanotubes (CNTs) has been prepared. With an aim of improving the dispersability of CNTs in ANI monomer, we synthesize CNTs/ANI complexes using a reflux technique which can be electrochemically polymerized to form well‐dispersed CNTs/polyaniline (PANI) films. The refluxed CNTs/ANI solution can be used to prepare high porous CNTs/PANI network via an electrochemical polymerization for applying as counter electrodes in dye‐sensitized solar cells. Compared with the pristine PANI, the multiwalled CNTs/PANI network shows more porous morphology and higher electrocatalytic activity, resulting in the acceleration of the reaction (triiodide (I^3?) to iodide (I^?)) of the redox electrolyte. The enhancement of the electrocatalytic activity is attributed to the interactions between multiwalled CNTs and PANI, promoting the quinoid ring structure and thus enhancing the conductivity of the polymer chains. The device, assembled with multiwalled CNTs/PANI network as counter electrodes, delivers 7.67% power conversion efficiency, which is comparable to 7.43% of that with Pt. Copyright © 2014 John Wiley & Sons, Ltd.     

From Open‐Shell Singlet Diradicaloid to Closed‐Shell Global Antiaromatic Macrocycles

A dithieno[a,h]‐s‐indacene‐ (DTI‐) based diradicaloid DTI‐2Br was synthesized and its open‐shell singlet diradical character was validated by magnetic measurements. On the other hand, its macrocyclic trimer DTI‐MC3 and tetramer DTI‐MC4 turned out to be closed‐shell compounds with global antiaromaticity, which was supported by X‐ray crystallographic analysis and NMR spectroscopy, assisted by ACID and 2D‐ICSS calculations. Such change can be explained by a subtle balance between two types of antiferromagnetic spin–spin coupling along the π‐conjugated macrocycles. The dications of DTI‐MC3 and DTI‐MC4 turned out to be open‐shell singlet diradical dications, with a singlet–triplet energy gap of ?2.90 and ?2.60 kcal mol^?1, respectively. At the same time, they are both global aromatic. Our studies show that intramolecular spin–spin interactions play important roles on electronic properties of π‐conjugated macrocycles.     

Stability and bounded of solutions to non-autonomous delay differential equations of third order

Nonlinear Dynamics - In this paper, we obtain some sufficient conditions to guarantee the uniform asymptotic stability of zero solution and bounded of all solutions to non-autonomous delay...     

Spectral studies of safranin-O in different surfactant solutions

The interaction of Safranin-O (SO), a cationic dye, with various surfactants viz., anionics; Sodiumdodecylsulfate (SDS) and Sodiumdodecylsulfonate (SDSo), nonionics; polyoxyethylenesorbitanmonolaurate (Tween 20) and polyoxyethylenedodecylether (Brij 35), cationic; Dodecyltrimethylammoniumbromide (DTAB) and zwitterionic; Laurylsulfobetaine (LSB) was studied spectrophotometrically as a function of surfactant concentration ranging from premicellar to postmicellar region in aqueous media in the absence and presence of cosolvents. The binding constants (K(b)) and fraction of bound SO to micelles (f), were calculated by means of Benesi-Hildebrand Equation. The binding tendency of SO to micelles followed the order as; Tween 20>Brij 35>SDS>SDSo>LSB. The presence of cosolvents, such as Methanol, Dimethylformamide (DMFA) and 1,4 Dioxan (DX) at various volume percentages, increased the CMC of both SDS and Tween 20 and at a certain concentration totally inhibited the micellization. The binding of SO to micelles decreased as the concentration of the cosolvents increased. This inhibitory effect of cosolvents on binding of SO to micelles followed the order as; Methanol>DMFA>DX.     

A novel resorufin based fluorescent “turn-on” probe for the selective detection of hydrazine and application in living cells

In this study, a resorufin derivative RTP-1, which is a novel fluorescent ‘‘turn-on' probe for sensitive detection of hydrazine within 30 min, is designed and synthesized. The selective deprotection of the ester group of the probe by hydrazine led to a prominent enhancement of fluorescent intensity, as well as a remarkable color change from colorless to pink, which could be distinguished by naked eye. The fluorescence enhancement showed decent linear relationship with hydrazine concentration ranging from 0 to 50 mmol/L, with a detection limit of 0.84 mmol/L. The specificity of RTP-1 for hydrazine to a number of metal ions, anions and amines is satisfactory. The sensing mechanism of RTP-1 and hydrazine was evaluated by HPLC, ESI mass spectrometry and density functional theory(DFT).Moreover, we have utilized this fluorescent probe for imaging hydrazine in living cells, and the fluorescence was clearly observed when the cells were incubated with hydrazine(100 mmol/L) for 30 min.     

一类三阶向量微分方程解的有界性和周期性

对某一类三阶向量微分方程周期解的存在性和解的毕竟有界性给出了充分条件。     

Ferrite films with enhanced stability of ferromagnetic resonance frequency

The problem of providing the frequency stability of magnetic vibrations of a ferrite film upon simultaneous changes in two magnetic parameters has been stated. The method of stabilizing the frequency of uniform ferromagnetic resonance at small deviations of the effective magnetization and the field of crystallographic magnetic anisotropy of the ferrite from initial values has been proposed. The equation that relates the frequency variation with variations in the magnetic parameters within a linear approximation has been derived. The possibility of the coefficients at the variations in the magnetic parameters to turn to zero has been investigated. It has been shown that this possibility can be implemented via the proper choice of the crystallographic film orientation and the strength and direction of the magnetizing field. In this case, the frequency shift has been determined by quadratic form over the variations in the magnetic parameters. An example of calculating the quadratic form has been given. The optimized film is compared with a film, the frequency shift of which is determined by a linear dependence on the variations in its magnetic parameters.     

Stability to vector Liénard equation with constant deviating argument

In this paper, we consider the vector Liénard equation with the constant deviating argument, τ>0, $$X''(t) + F\bigl(X(t),X'(t) \bigr)X'(t) + H\bigl(X(t - \tau)\bigr) = P(t) $$ in two cases: (i) P(.)≡0, (ii) P(.)≠0. Based on the Lyapunov–Krasovskii functional approach, the asymptotic stability of the zero solution and the boundedness of all solutions are discussed for these cases. We give an example to illustrate the theoretical analysis made in this work and to show the effectiveness of the method utilized here.