A novel turn-on fluorescent probe for Hg2+ detection based on rhodamine B spirolactam derivative

ABSTRACT

In this work, a new turn-on fluorescent probe 1 for Hg²⁺ ions detection based on rhodamine B spirolactam was reported. Among tested metal ions, probe 1 shows high selectivity towards Hg²⁺ in the the mixture solution of methanol and 0.02 M HEPES buffer (V/V = 9:1, pH = 7.2). No absorption and emission band of probe 1 was observed in the range from 450 to 700 nm. While only addition of Hg²⁺ to probe 1 could lead to appearance of a new absorption band centered at 553 nm and a fluorescence emission band around 577 nm upon excitation at 520 nm. Moreover, it exhibits excellent linear relationship (R² = 0.9993) between fluorescence intensity at 577 nm and the concentration of Hg²⁺ from 1.6 to 32 μM. The sensing mechanism was proven to be spirolactam ring open induced by Hg²⁺ through ¹H NMR, MS, absorption and fluorescence spectra. In addition, probe 1 could detect Hg²⁺ in real water samples and on filter paper, which demonstrates its application in environment science.     

Comment on “On the Neumann function and the method of images in spherical and ellipsoidal geometry”

In this note, we point out two errors in the article “On the Neumann function and the method of images in spherical and ellipsoidal geometry” by Dassios and Sten. Two corrections are then proposed.     

Validated UPLC‐MS/MS method for determination of moclobemide in human brain cell supernatant and its application to bidirectional transport study

A simple and sensitive analytical method based on ultraperformance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) has been developed for determination of moclobemide in human brain cell monolayer as an in vitro model of blood–brain barrier. Brucine was employed as the internal standard. Moclobemide and internal standard were extracted from cell supernatant by ethyl acetate after alkalinizing with sodium hydroxide. The UPLC separation was performed on an Acquity UPLC^TM BEH C₁₈ column (50 × 2.1 mm, 1.7 µm, Waters, USA) with a mobile phase consisting of methanol–water (29.5:70.5, v/v); the water in the mobile phase contained 0.05% ammonium acetate and 0.1% formic acid. Detection of the analytes was achieved using positive ion electrospray via multiple reaction monitoring mode. The mass transitions were m/z 269.16 → 182.01 for moclobemide and m/z 395.24 → 324.15 for brucine. The extraction recovery was 83.0–83.4% and the lower limit of quantitation (LLOQ) was 1.0 ng/mL for moclobemide. The method was validated from LLOQ to 1980 ng/mL with a coefficient of determination greater than 0.999. Intra‐ and inter‐day accuracies of the method at three concentrations ranged from 89.1 to 100.9% for moclobemide with precision of 1.1–9.6%. This validated method was successfully applied to bidirectional transport study of moclobemide blood–brain barrier permeability. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and photovoltaic properties of main chain polymeric metal complexes containing 1,10‐phenanthroline metal complexes conjugating alkyl fluorene or alkoxy benzene by C═C bridge for dye‐sensitized solar cells

Four main chain polymeric metal complexes (P1–P4) based on 1,10‐phenanthroline metal complexes via the Heck coupling have been synthesized and characterized by Fourier transform infrared spectroscopy, ¹H NMR, UV–Vis absorption, photoluminescence spectroscopy, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, elemental analysis, and cyclic voltammetry. To investigate their photovoltaic properties, the dye‐sensitized solar cells based on these polymers dyes are studied, under the illumination of AM 1.5G, 100 mW/cm². The study results show the four polymers exhibit good thermally stable and the solar cells based on them have good device performance, and the maximum power conversion efficiency is up to 0.735% for the solar cells based on P3 with a short‐circuit current (J_sc) of 1.68 mA/cm² and an open‐circuit voltage (V_oc) of 0.62 V. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on the Cationic Copolymerization of α-Pinene and Styrene with Complex SbCl3/AlCl3 Catalyst Systems. I. Effects of the Polymerization Conditions on the Copolymerization Products

Abstract

The copolymerization products of α-pinene and styrene were prepared with the compound catalyst system SbCl₃/AlCl₃ by changing the Sb/Al ratio, feeding monomer ratio, solvent, and polymerization temperature. The compositions of the copolymerization products were quantitatively characterized by the method of the combination of micro-ozonization and thin-layer chromatography in terms of the contents of the homopolymers and the copolymers containing high or low mole fractions of α-pinene, the yields of pure copolymer, and the monomer unit ratios (F ₁) of copolymers. The results show that it was easier to obtain the higher yield (up to 80%) of the pure copolymer with the complex catalyst system than with AlCl₃ alone. The F ₁ values could be controlled between 30 and 56% under the following polymerization conditions: Sb/Al  1/2, α-pinene/styrene  70%, and the conversion of styrene  90%.     

The split common fixed point problem for infinite families of total quasi-asymptotically nonexpansive operators

The main purpose in this paper is to introduce an original technique, namely, a specific way of choosing the indexes of the involved operators, by which a new iterative algorithm is developed for solving the split common fixed point problem for infinite families of total quasi-asymptotically nonexpansive operators and some strong and weak convergence theorems are established for this class of nonlinear operators in the framework of infinite-dimensional Hilbert spaces. The result is more applicable than those of other authors with related interest.     

Superresolution imaging of DNA tetrahedral nanostructures in cells by STED method with continuous wave lasers

DNA tetrahedral nanostructures are considered to be uew nanocarriers because they can be precisely controlled and hold excellent penetration ability to the cellular membrane. Although the DNA tetrahedral nanostructure is extensively studied in biology and medicine, its behavior in the cells with nanoscale resolution is not understood clearly. In this letter, we demonstrate superrcsolution fluorescence imaging of the distribution of DNA tetrahedral nanostructures in the cell with a simulated emission depletion （STED） microscope, which is built based on a conventional eonfocal microscope and can t）rovide a resolution of 70 nm.