Mechanistic Insights into the Fluorescence Quenching of Rhodamine 6G by Graphene Oxide

The fluorescence quenching of Rhodamine 6G (R6G) by graphene oxide (GO) was interrogated by R6G fluorescence measurements using a set of controlled GO samples with varied C/O ratios as the quencher.The carbonyl groups on the GO nanosheet turned to play a dominant role in quenching the R6G fluorescence.The quenching in the static regime can be described by the "sphere of action" model.The significant absorption of the R6G fluorescence by the ground-state complex formed between R6G and GO was identified to be responsible for the static quenching.This work offers helpful insights into the fluorescence quenching mechanisms in the R6G/GO system.     

一种增色检测铜离子的新型罗丹明B衍生物探针

合成了一种新型罗丹明B衍生物,(5-醛基吡咯-2-酸乙酯)罗丹明B酰肼西夫碱(RHPS)。在含30%乙腈的Tris-HCl缓冲溶液(pH=7.0)中,该探针本身无色,加入铜离子后溶液很快变为粉红色,而对其它金属离子如铁、汞、铅和镁等都没有明显响应。该探针与铜离子的结合是一个可逆过程,因此可应用于环境中铜离子的快速实时检测,线性范围为1.0×10-7～6.0×10-6mol/L,检出限达1.2×10-8mol/L。     

动力学荧光法测定对苯二酚的研究

基于在稀H2SO4介质中,对苯二酚对H2O2氧化罗丹明B产生的荧光猝灭有显著的催化作用,建立了测定对苯二酚的动力学荧光分析法。反应在80℃的水浴中进行12 min,方法的线性范围为4.0~600.0μg/L,检出限为3.7μg/L。该方法用于水样中对苯二酚的测定,加标回收率在96.4%~101.3%之间,相对标准偏差为2.2%。     

The adsorption of dyes used in the textile industry on mesoporous materials

An adsorbent material made with a silica lamellar mesoporous material treated with chitosan has been proved to be useful to adsorb both anionic and cationic dyes used in the textile industry. The two tested dyes Tectilon Blue (anionic) and Rhodamine B (cationic) have different adsorption kinetics reflecting a complex mechanism of the phenomenon. Furthermore, the adsorption capacity and interaction strength of Tectilon Blue is higher than those of Rhodamine B. Tectilon Blue molecules are situated with the molecular plane perpendicular to the adsorbent surface, whilst that of the Rhodamine B molecule is flat and parallel to the surface. The differences may be attributed to the different regions of the adsorbent surface on which the dyes are adsorbed because of their different electric charge.     

罗丹明6G在醇溶液中的荧光频移特性分析

罗丹明6G在甲醇、乙醇、乙二醇溶液中均发出较强的荧光。当醇溶液浓度为33.3%时,基本不存在频移现象。当醇溶液浓度为99.7%时,荧光峰发生蓝移或红移,分析认为该频移是由罗丹明6G和醇类物质分子相互作用(如氢键、静电吸引)导致激发态能量升高、荧光峰蓝移,与醇类物质分子中羟基OH的孤对电子跃迁导致荧光能量降低、荧光峰红移,这两种因素相互竞争的结果,且在高浓度醇溶液中,羟基OH数量越多,红移越明显。     

Shape-controlled synthesis and photocatalytic activity of In2O3 nanostructures derived from coordination polymer precursors

In（BTC）（phen）（H₂O）nanocrystals with controllable morphology and size were successfully obtained by solvothermal method.Hierarchical straw-sheaf-like architectures,nanorods and elongated hexagons have been synthesized by varying the volume ratio of DMF:H₂O:C₂H₅OH.Phase-pure In₂O₃nanocrystals were obtained by the calcination of the precursors without significant alteration of the morphology.The products were characterized by PXRD,SEM,TEM,TGA,IR and gas adsorption measurements.The photocatalytic effect was investigated for the In₂O₃ nanocrystals with different morphology on the degradation of rhodamine B（Rh B）and it was found that the nanorods exhibited the best photocatalytic activity,which shows the degradation efficiency of 94%for 8 h.The results showed that the photocatalytic activity increased with the increase of BET surface area and pore volume.     

催化动力学光度法测定栗子和香菇中痕量Se(Ⅳ)

探讨了Se(Ⅳ)在HNO_3介质中催化KBrO3氧化罗丹明B的褪色反应及最优的动力学条件,由此建立了动力学荧光光度法测定痕量Se(Ⅳ)的新方法。测定Se(Ⅳ)的线性范围为0.2~2.2μg·L~(-1),检出限为0.004μg·L~(-1)。方法用于测定栗子和蘑菇中的痕量Se(Ⅳ),获得了满意的结果。     

Rhodamine-based chemodosimeter for fluorescent determination of Hg in 100% aqueous solution and in living cells

A rhodamine spirolactam derivative (1) bearing a hydrophilic carboxylic acid group is developed as a fluorescent chemodosimeter for bivalent mercury ions (Hg²⁺) in 100% aqueous solution. It exhibits a highly sensitive “turn-on” fluorescent response toward Hg²⁺ with a 42-fold fluorescence intensity enhancement under 1 equiv. of Hg²⁺ added. The chemodosimeter can be applied to the quantification of Hg²⁺ with a linear range covering from 3.0 × 10⁻⁷ to 1.0 × 10⁻⁵ M and a detection limit of 9.7 × 10⁻⁸ M. Most importantly, the fluorescence changes of the chemodosimeter are remarkably specific for Hg²⁺ in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the experiment results show that the response behavior of 1 towards Hg²⁺ is pH independent in neutral condition (pH 5.0–8.0) and the response is fast (response time less than 3 min). Furthermore, the ring-opening mechanism of the rhodamine spirolactam induced by Hg²⁺ was supported by NMR, MS, and DFT theoretical calculations. In addition, the proposed chemodosimeter has been used to detect Hg²⁺ in water samples and image Hg²⁺ in living cells with satisfying results.     

Computational design and fabrication of core–shell magnetic molecularly imprinted polymer for dispersive micro‐solid‐phase extraction coupled with high‐performance liquid chromatography for the determination of rhodamine 6G

A novel core–shell magnetic nano‐adsorbent with surface molecularly imprinted polymer coating was fabricated and then applied to dispersive micro‐solid‐phase extraction followed by determination of rhodamine 6G using high‐performance liquid chromatography. The molecularly imprinted polymer coating was prepared by copolymerization of dopamine and m‐aminophenylboronic acid (functional monomers), in the presence of rhodamine 6G (template). The selection of the suitable functional monomers was based on the interaction between different monomers and the template using the density functional theory. The ratios of the monomers to template were further optimized by an OA₉ (3⁴) orthogonal array design. The binding performances of the adsorbent were evaluated by static, kinetic, and selective adsorption experiments. The results reveal that the adsorbent possesses remarkable affinity and binding specificity for rhodamine 6G because of the enhanced Lewis acid‐base interaction between the B(Ш) embedded in the imprinted cavities and the template. The nano‐adsorbent was successfully applied to dispersive micro‐solid‐phase extraction coupled to high‐performance liquid chromatography for the trace determination of rhodamine 6G in samples with a detection limit of 2.7 nmol/L. Spiked recoveries ranged from 93.0–99.1, 89.5–92.7, and 86.9–105% in river water, matrimony vine and paprika samples, respectively, with relative standard deviations of less than 4.3%.     

Sensitive detection and separation of fluorescent derivatives using capillary electrophoresis with laser-induced fluorescence detection with 532 nm Nd:YAG laser

Capillary electrophoresis with laser-induced fluorescence detection (CELIF) is a powerful tool for separation and sensitive determination of fluorescent species. Biologically active compounds, such as amino acids, peptides and proteins may exhibit native fluorescence, which is however often low and/or an expensive laser is required for excitation in UV. Therefore, labelling of the analytes with a fluorescent dye is usually necessary.In this work, a home-built CELIF instrument with diode pumped frequency-doubled continuous wave Nd:YAG excitation laser with feedback power regulation (532 nm) was constructed. The suitability of this type of laser for LIF detection in a separation method was found excellent. A limit of detection (LOD) (S/N=3) of 2×10⁻¹³ mol/l was achieved with rhodamine B, which is comparable to those obtained using similar instruments with Ar⁺ laser [Y.F. Cheng, N.J. Dovichi, Science 242 (1988) 562, E.S. Yeung et al., J. Chromatogr. 608 (1992) 73]. LOD of a protein derivatized according to modified procedures [M.J. Little et al., Anal. Chim. Acta 339 (1997) 279, A. Chersi et al., Biochim. Biophys. Acta 1336 (1997) 83] was determined. Detection of the derivatives was found to be limited by insufficient reaction recovery at low analyte concentration, chemical noise, separation efficiency and quality of the derivatizing reagent rather than by the detector performance. As a consequence, a huge gap between the detection ability of CELIF instruments and LOD determined in real samples is revealed.