A Ratiometric Fluorescent Sensor for Cd2+ Based on Internal Charge Transfer.

This work reports on a novel fluorescent sensor 1 for Cd2+ ion based on the fluorophore of tetramethyl substituted bis(difluoroboron)-1,2-bis[(1H-pyrrol-2-yl)methylene]hydrazine (Me4BOPHY), which is modified with an electron donor moiety of N,N-bis(pyridin-2-ylmethyl)benzenamine. Sensor 1 has absorption and emission in visible region, at 550 nm and 675 nm, respectively. The long wavelength spectral response makes it easier to fabricate the fluorescence detector. The sensor mechanism is based on the tunable internal charge transfer (ICT) transition of molecule 1. Binding of Cd2+ ion quenches the ICT transition, but turns on the π - π transition of the fluorophore, thus enabling ratiometric fluorescence sensing. The limit of detection (LOD) was projected down to 0.77 ppb, which is far below the safety value (3 ppb) set for drinking water by World Health Organization. The sensor also demonstrates a high selectivity towards Cd2+ in comparison to other interferent metal ions.

A Fluorescent Sensor Synthesized Using Silica Nanoparticles for Detecting Hg²âº in Aqueous Solution.

With the aim of detecting Hg²âº in aqueous solution, a new fluorescent nanosensor (RhB-APTES-SiNPs) for the determination of Hg²âº has been successfully developed. This senor was synthesized by immobilizing RhB-APTES on the surface of silica nanoparticles (SiNPs), which were prepared using the reverse microemulsion method. RhB-APTES-SiNPs can detect Hg²âº on-line, in real time and with the naked eye, thus providing "turn-on" fluorescence enhancement. The developed nanosensor exhibits highly sensitivity and selectivity over several cations in aqueous solution. Additionally, RhB-APTES-SiNPs exhibits an excellent ability to detect Hg²âº within a linear range from 1 to 6 µM, and its detection limit was calculated to be 0.5 ppb.

4,4'-Bipyridine-dimethyl-glyoxime (1/1).

In the title compound, C(10)H(8)N(2)·C(4)H(8)N(2)O(2), both the dimethyl-glyoxime and the 4,4'-bipyridine mol-ecules have crystallographic C(i) symmetry. The mol-ecules stack along the a-axis direction with a dihedral angle of 20.4 (8)° between their planes. In the crystal, the components are linked by O-H⋯N hydrogen bonds into alternating chains along [120] and [1[Formula: see text]0].

In situ green oxidation synthesis of Ti3+ and N self-doped SrTiO x N y nanoparticles with enhanced photocatalytic activity under visible light.

A simple in situ green oxidation synthesis route was developed to prepare Ti3+ and N self-doped SrTiO x N y nanoparticles using TiN and H2O2 as precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to characterize the crystallinity, structure and morphology. X-ray photoelectron spectroscopy (XPS) tests confirmed the presence of Ti3+ and N in the prepared SrTiO x N y nanoparticles. The resultant nanoparticles were shown to have strong absorption from 400 to 800 nm using UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The formation mechanism of the Ti3+ and N self-doped SrTiO x N y nanoparticles was also discussed. Under visible light irradiation, the obtained Ti3+ and N self-doped samples showed higher photocatalytic activity for the degradation of the model wastewater, methylene blue (MB) solution. The most active sample T-130-Vac, obtained at 130 °C under vacuum, showed a 9.5-fold enhancement in the visible light decomposition of MB in comparison to the commercial catalyst nano-SrTiO3. The sample also showed a relatively high cycling stability for photocatalytic activity.

An aqueous fluorescent sensor for Pb2+ based on phenothiazine-polyamide.

A sensitive and selective fluorescent sensor for Pb2+ ion based on phenothiazine-polyamide was built (named sensor PP). Due to introducing of four diethanolamine groups to polyamide, this sensor was totally water soluble. PP could detect Pb2+ ion within 1 min in the presence of other metal ions in aqueous solution, the detect limit was 9.11 × 10-8 M.