Flow-through room temperature phosphorescence optosensing for the determination of lead in sea water

The chelates formed between the heavy metal ion Pb(II) and the reagents 8-hydroxy-5-quinolinesulphonic acid, 8-hydroxy-7-quinolinesulphonic acid and 8-hydroxy-7-iodo-5-quinolinesulphonic acid exhibit strong room temperature phosphorescence (RTP) if retained on the surface of anion exchange resin beads. Based on the on-line formation, in a flow-injection system, of such RTP lead chelates and their transient immobilization on an anion exchange resin, three flow-through optosensing systems are investigated for lead in sea water. Optimum experimental conditions and the analytical performance characteristics of the three optosensors are discussed. Relative standard deviations (RSDs) of the order of 3% are typical at 100 ng ml−1 Pb(II) and the active sensing phases can easily be regenerated by passing 500 μl of 6 M hydrochloric acid. A lead(II) detection limit of 0.1 ng ml−1 (3×background SD, for 2 ml sample injection volumes) was achieved for the optosensor based on 8-hydroxy-7-quinolinesulphonic acid. Possible interferences present in sea water, including cations and anions which could affect the sensor response, are discussed in detail. Finally, the selected RTP flow-through optical sensor has been successfully tested for the determination of lead in sea water at a few ng ml−1.

Determination of lead using a poly(vinyl chloride)-based crown ether membrane

A poly(vinyl chloride)(PVC)-based membrane of 15-crown-5 exhibits a good response for lead(II) ions over a wide concentration range. The response time of the sensor is 30 s and the membrane can be used for more than four months without observing any divergence. The selectivity of the sensor is comparable with those reported for other such electrodes. It was possible to determine lead in polluted waters using this electrode assembly.

Solution-processable highly efficient yellow- and red-emitting phosphorescent organic light emitting devices from a small molecule bipolar host and iridium complexes

A bipolar transport compound, 2,5-bis(4-(9-(2-ethylhexyl)-9H-carbazol-3-yl) phenyl)-1,3,4-oxadiazole (CzOXD), incorporating both electron-and hole-transport functionalities, was synthesized and fully characterized by H-1 NMR, C-13 NMR, elemental analysis and mass spectrometry. Its thermal, electrochemical, electronic absorption and photoluminescent properties were studied

Red-light-emitting iridium complexes with hole-transporting 9-arylcarbazole moieties for electrophosphorescence efficiency/color purity trade-off optimizationE

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations

Efficient red organic light-emitting diode sensitized by phosphorescent Ir compound

The efficiencies of red organic light-emitting diode (OLED) using tris-(8-hydroxy-quinoline)aluminum (Alq(3)) as host and 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) as dopant were greatly increased by adding a small amount (0.3 wt%) of Ir compound, iridium(III) bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-N-',C-4) (acetyl acetonate) (Ir(C6)(2)(acac)), as a sensitizer

Red-Light-Emitting Iridium Complexes with Hole-Transporting 9-Arylcarbazole Moieties for Electrophosphorescence Efficiency/ Color Purity Trade-off Optimization

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations. The highest occupied molecular orbital levels of these complexes are raised by the integration of a carbazole unit to the iridium isoquinoline core so that the hole-transporting ability is improved in the resulting complexes relative to those with I-phenylisoquinoline ligands. All of the complexes are highly thermally stable and emit an intense red light at room temperature with relatively short lifetimes that are beneficial for highly efficient organic light-emitting diodes (OLEDs).

Red and green upconversion luminescence of Gd2O3 : Er3+, Yb3+ nanoparticles

Gd2O3:Er3+, Yb3+ nanoparticles have been synthesized by a homogeneous precipitation method with EDTA 2Na of two different concentrations. Upconversion luminescence spectra of the samples have been studied under 980 nm laser excitation. The results of XRD show that obtained Gd2O3:Er3+, Yb3+ nanoparticles are of a cubic structure. The average crystallite sizes could be calculated as 22 and 29 nm, respectively. The strong green and red upconversion emission were observed, and attributed to the H-2(11/2), S-4(3/2) -> I-4(15/2) and F-4(19/2) -> I-4(15/2) transitions of Er3+ ion, respectively.

A Dithienylbenzothiadiazole Pure Red Molecular Emitter with Electron Transport and Exciton Self-Confinement for Nondoped Organic Red-Light-Emitting Diodes

An amorphous photoluminescent material based on a dithienylbenzothiadiazole structure has been used for the fabrication of organic red-light-emitting diodes. The synergistic effects of the electron-transport ability and exciton confinement of the emitting material allow for the fabrication of efficient pure-red-light-emitting devices without a hole blocker.

DNAzyme-based Colorimetric Sensing of Lead (Pb2+) Using Unmodified Gold Nanoparticle Probes

Novel functional oligonucleotides, especially DNAzymes with RNA-cleavage activity, have been intensively studied due to their potential applications in therapeutics and sensors. Taking advantage of the high specificity of 17E DNAzyme for Pb2+, highly sensitive and selective fluorescent, electrochemical and colorimetric sensors have been developed for Pb2+. In this work, we report a simple, sensitive and label-free 17E DNAzyme-based sensor for Pb2+ detection using unmodified gold nanoparticles (GNPs) based on the fact that unfolded single-stranded DNA could be adsorbed on the citrate protected GNPs while double-stranded DNA could not. By our method the substrate cleavage by the 17E DNAzyme in the presence of Pb2+ could be monitored by color change of GNPs, thereby Pb2+ detection was realized.

Solution-Processible Red Iridium Dendrimers based on Oligocarbazole Host Dendrons: Synthesis, Properties, and their Applications in Organic Light-Emitting Diodes

A series of novel red-emitting iridium dendrimers functionalized with oligocarbazole host dendrons up to the third generation (red-G3) have been synthesized by a convergent method, and their photophysical, electrochemical, and electroluminescent properties have been investigated. In addition to controlling the intermolecular interactions, oligocarbazole-based dendrons could also participate in the electrochemical and charge-transporting process. As a result, highly efficient electrophosphorescent devices can be fabricated by spin-coating from chlorobenzene solution in different device configurations.

Highly efficient red electroluminescent polymers with dopant/host system and molecular dispersion feature: polyfluorene as the host and 2,1,3-benzothiadiazole derivatives as the red dopant

By selecting polyfluorene as the polymer host, choosing 2,1,3-benzothiadiazole derivative moieties as the red dopant units and covalently attaching 0.3 mol% of the dopant units to the side chain of the polymer host, we developed a novel series of red electroluminescent polymers of dopant/host system with molecular dispersion feature. Their EL spectra exhibited predominant red emission from the dopant units because of the energy transfer and charge trapping from the polymer backbone to the dopant units. The emission wavelength of the polymers could be tuned by modifying the chemical structures of the dopant units.

SiO2 nanoparticles as scatterers for random organic laser action in red fluorescent dye 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped polystyrene films

Random multimode lasers are achieved in 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polystyrene thin films by introducing silicon dioxide (SiO2) nanoparticles as scatterers. The devices emit a resonance multimode peak at a center wavelength of 640 nm with a mode linewidth less than 0.87 nm. The threshold excitation intensity is as low as 0.25 mJ pulse(-1) cm(-2). It can be seen that the microscopic random resonance cavities can be formed by multiple scattering of SiO2 nanoparticles.

Efficient white organic light-emitting diodes using europium complex as the red unit

Efficient white organic light-emitting diodes (WOLEDs) using europium complex as the red unit are presented. The WOLEDs were fabricated by using the structure of indium tin oxide (ITO)/N, N'-di(naphthalene-1-yl)-N, N'-diphenyl-benzidine (NPB)/4,4-N, N-dicarbazolebiphenyl (CBP) : bis(2,4-diphenylquinolyl-N, C-2) iridium (acetylacetonate) ((PPQ)(2)Ir(acac)) : Eu (III) tris(thenoyltrifluoroacetone) 3,4,7,8-tetramethyl-1,10-phenanthroline (Eu(TTA)(3)(Tmphen))/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN) : p-bis (p-N, N-di-phenyl-aminostyryl)benzene (DSA-Ph)/9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminium (Alq3)/LiF/Al.