A triethylene glycol di-imine locked triazole linked bis-calix[4]arene conjugate L has been synthesised and characterised. Conjugate L exhibits high fluorescence enhancement towards Zn2+ among the 13 metal ions studied down to a lower detection limit of ~12 ppb. The absorption and visual colour change experiments differentiated the Zn2+ from the other metal ions studied. The isolated zinc complex, [Zn2L] has been used as a chemo-sensing ensemble for the recognition of anions based on their binding affinities towards Zn2+. [Zn2L] was found to be sensitive and selective towards phosphate-bearing species and in particular to adenosine triphosphate (ATP2 ? ) among the other 20 anions studied as observed based on the changes occurred in the fluorescence intensity. The selectivity of the ATP2 ? has been shown on the basis of the changes observed in the emission and absorption spectral studies. The lowest detectable concentration for ATP2 ? with the chemo-sensing ensemble [Zn2L] is 348 ppb in methanol. The fluorescence quenching by the phosphate-based anions has been modelled by molecular mechanics studies and found that the anions possessing two or more phosphate moieties can only bridge between the two zinc centres, and hence those possessing only one phosphate moiety (H2PO4? and AMP2 ? ) are ineffective. 相似文献
The hepatitis B surface antigen manufactured by recombinant DNA technology is extracted from the culture media by density gradient centrifugation using cesium salts. Cesium is considered to be toxic, because it affects active ion transport by blocking potassium channels. The residual trace levels of cesium in hepatitis B vaccine samples are determined by suppressed ion chromatography. Hepatitis B vaccines contain various buffer salts, aluminum-containing adjuvants, proteins and traces of iron. The polyvalent cations (Al3+, Fe3+) and proteins degrade the chromatographic performance in terms of decreased retention time and poor reproducibility. Different sample preparation approaches were evaluated with the aim of eliminating these foulants: (1) filtration, (2) digestion and (3) digestion-protein precipitation. Quantitative elimination of these foulants was achieved in the digestion-protein precipitation sample clean-up approach. Cesium was separated on the IonPac CS17 column with suppressed conductivity detection. The results of the ion chromatography (IC) method were compared with ICP-MS analysis. The precision of determination was better than 6.5% (relative standard deviation) with a method detection limit of 45 ng mL−1. The expanded uncertainty in the measurement at 95% confidence level (coverage factor 2) is better than 16.3%.
New 2‐(4′‐9H‐carbazole‐9‐yl)‐styryl‐1H‐phenathro[9,10‐d]imidazole‐1‐yl)benzonitrile (SPICN‐Cz) and 4‐(2‐(4‐(diphenylamino)phenyl‐styryl‐1H‐phenathro[9,10‐d]imidazole‐1‐yl)benzonitrile (SPICN‐TPA) have been synthesised, and their photophysical, electrochemical, and electroluminescent properties were analysed in comparison with their cyano‐free parent compounds, SPI‐Cz, and SPI‐TPA. Solvatochromic effects show the transformation of an excited state character from locally excited (LE) state to charge transfer (CT) state. Using time‐dependent density functional theory calculation, the excited state properties of these donor‐acceptor blue emissive materials have been analysed. Their excited state properties have been tuned by replacing the strong donor triphenylamine to weak donor carbazole to achieve the combination of high photoluminance efficiency locally excited (LE) component and high exciton‐utilizing CT component in one excited state. Hybridization processes between LE and CT components of SPICN‐Cz and SPICN‐TPA in the emissive state have been discussed. The nondoped organic light emitting diode device based on SPICN‐Cz exhibit better electroluminescent performances than those of SPICN‐TPA–based device: high external quantum efficiency of 2.58 %, current efficiency of 2.90 cd A‐1, and power efficiency of 2.26 lm W‐1 with Commission Internationale de l'Éclairage (CIE) coordinates of (0.15, 0.12). The excited state modulation and the composition of LE and CT states in the donor‐acceptor system could be useful to design low‐cost, high‐efficiency fluorescent organic light emitting diode materials. 相似文献