Frontiers in chiral phosphorescent complexes for circularly polarized electroluminescence.

Materials with circularly polarized luminescence properties have attracted wide attention in recent years. One of the most important applications of these materials is for circularly polarized organic light emitting diodes (CP-OLEDs), which have potential application in 3D displays. Chiral conjugated polymers, small organic molecules and metal complexes have already been employed as emitters for CP-OLEDs. Benefiting from the ability to harvest both singlet and triplet excitons, chiral phosphorescent metal complexes always show outstanding device performance. In this article we briefly discuss the recent progress, current challenges and out look of chiral phosphorescent metal complexes.

Circularly Polarized White Organic Light-Emitting Diodes Based on Spiro-Type Thermally Activated Delayed Fluorescence Materials.

In this study, we report the first circularly polarized white organic light-emitting diodes (CP-WOLEDs) based on all thermally activated delayed fluorescence (TADF) materials. Two pairs of spiro-type TADF enantiomers, (R/S)-SPOCN (5,5'-((2,2',3,3'-tetrahydro-1,1'-spirobi[indene]-7,7'-diyl)bis(oxy))bis(4-(10H-phenoxazin-10-yl)phthalonitrile)) and (R/S)-OSFSO (2'-(trifluoromethyl)-spiro[quinolino[3,2,1-kl]phenoxazine-9,9'-thioxanthene]-10',10'-dioxide), serve as emitters with complementary emission. The CP-OLEDs exhibit warm white emission with a CIE coordinate of (0.35, 0.46). Besides, decent device performances are observed with an external quantum efficiency of up to 21.6 % at maximum and 11.8 % at 1000 cd m-2 . Obvious circularly polarized electroluminescence signals are detected with a dissymmetry factor |gEL | of around 3.0×10-3 . This is the first report of CP-WOLEDs that can harvest both singlet and triplet excitons, which provides a feasible strategy for the development of CP-WOLEDs with remarkable device performances.

Chiral Spiro-Axis Induced Blue Thermally Activated Delayed Fluorescence Material for Efficient Circularly Polarized OLEDs with Low Efficiency Roll-Off.

A spiro-axis skeleton not only introduces circularly polarized luminescence (CPL) into thermally activated delayed fluorescence (TADF) molecules but also enhances the intramolecular through space charge transfer (TSCT) process. Spiral distributed phenoxazine and 2-(trifluoromethyl)-9H-thioxanthen-9-one-10,10-dioxide act as donor and acceptor units, respectively. The resulting TADF enantiomers, (rac)-OSFSO, display emission maxima at 470 nm, small singlet-triplet energy gap (ΔEST ) of 0.022 eV and high photoluminescence quantum yield (PLQY) of 81.2 % in co-doped film. The circularly polarized OLEDs (CP-OLEDs) based on (R)-OSFSO and (S)-OSFSO display obvious circularly polarized electroluminescence (CPEL) signals with dissymmetry factor up to 3.0×10-3 and maximum external quantum efficiency (EQEmax ) of 20.0 %. Moreover, the devices show remarkably low efficiency roll-off with an EQE of 19.3 % at 1000 cd m-2 (roll-off ca. 3.5 %), which are among the top results of CP-OLEDs.

Optimized self-immolative near-infrared probe based on hemicyanine for highly specific monitoring thiophenols in living systems.

In this paper, utilizing the same recognition group dinitrophenyl and hydroxyl functional NIR fluorophore hemicyanine, directly-linked probe CyNO2 and self-immolative probe CyBNO2 were developed for evaluation of sensing PhSH. Though CyNO2 was easily synthesized and sensitive to mercapto, the probe CyBNO2 showed higher selectivity, broader linear range from 1.0 × 10-7 to 7.0 × 10-6 M with lower detection limit of 22 nM for PhSH. Moreover, CyBNO2 was successfully applied for monitoring PhSH in living cells and in vivo, indicating the great potential of self-immolative probes.

A novel weak acid activated probe for highly selective monitoring selenocysteine in living cells.

Selenocysteine (Sec, pKa 5.8) is genetically encoded 21st amino acid into the active site of selenoproteins, which have broad functions relevant to various diseases, tissues or organs and subcellular organelles. However, many selenoproteins involved cellular functions still remains unclear. In addition, since biothiols such as glutathione (GSH, pKa 8.3), possessing similar chemical properties with Sec, commonly exist in living systems at high levels. Thus, it is of great importance and high challenge to identify novel probes for selectively monitoring Sec over biothiols. In this paper, we proposed a smart strategy which allowed us to develop a lysosome targetable probe for specifically sensing Sec. By restricting weak acidic microenvironment, the probe shows a specific detection for Sec with 85-fold fluorescence enhancement owing to the remaining high activity of Sec at pH 5.0. Moreover, being low cytotoxicity to the cells verified by MTS assay, the probe was then successfully applied for imaging exogenous and endogenous Sec in lysosomes, indicating its potential for the biological investigation of Sec in subcellular organelles.

[Effect of Elodea nuttallii-Immobilized Nitrogen Cycling Bacteria on the Mechanism of Nitrogen Removal in Polluted River Water].

Surface water, Elodea nuttallii and undisturbed sediment cores from the Qinshui River in Gonghu Bay were collected to carry out a simulation experiment in a laboratory to study the effect of Elodea nuttallii-immobilized nitrogen-cycling bacteria on nitrogen removal mechanisms from the river water. In this study, the transformation and fate of ammonium among four different treatment groups were investigated by using a stable 15 N isotope pairing technique combined with high-throughput sequencing technology[Treatment A:bare sediment, Treatment B:sediment+immobilized nitrogen cycling bacteria (INCB), Treatment C:sediment+E. nuttallii, Treatment D:sediment+INCB+E. nuttallii]. The results of the 15 N mass-balance model showed that there were three pathways to the ultimate fate of nitrogen:precipitated with the sediments, absorbed by E. nuttallii, and consumed by microbial processes[denitrification and anaerobic ammonium oxidation (ANAMMOX)]. The percentages of E. nuttallii assimilated in the 15 NH4+ were 25.44% and 19.79% for treatments C and D. The sediment storage ratio of 15 NH4+ accounted for 7.94%, 5.52%, 6.47% and 4.86% in treatments A, B, C, and D, respectively. The proportion of 15 NH4+ lost as 15 N-labelled gas were 16.06%, 28.86%, 16.93% and 33.09% in the four different treatment groups, respectively. Denitrification and anammox were the bacterial primary processes in N2 and N2O production. The abundance and diversity of microorganisms was relatively higher in the treatment with E. nuttallii-immobilized nitrogen cycling bacteria (E-INCB) assemblage technology applied. Furthermore, the removal rates of 15 NH4+ were 24%, 34.38%, 48.84% and 57.74% in treatments A, B, C and D, respectively. These results show that the E-INCB assemblage technology may improve the capacity for nitrogen removal from the river water.

[Preparation of Nanocomposite Hydrogel and Its Adsorption of Heavy Metal Ions].

An acylamino and hydroxyl functionalized hydrogel [p(HMAm/HEA)] was newly prepared by the 60 Co-γ-induced polymerization of N-hydroxymethyl acrylamide (HMAm) and 2-hydroxyethyl acrylate (HEA). Then the copolymer p(HMAm/HEA) hydrogel was utilized for in situ nanosized hydrous manganese dioxide (HMO) loading to prepare nanocomposite hydrogel HMO-p(HMAm/HEA) for Pb2+ and Cu2+ removal. The nanocomposite hydrogel was characterized by SEM, TEM and FTIR, showing that p(HMAm/HEA) hydrogel was indeed a copolymer of HMAm and HEA monomers, and the loading of HMO nanoparticles onto p(HMAm/HEA) was successful. Various influencing parameters on heavy metal ions removal by HMO-p(HMAm/HEA), such as initial pH, temperature, initial heavy metal concentration, contact time and competing Ca2+ and Na+, were estimated. The results showed that the adsorption process was temperature-independent, pH-sensitive, Langmuir monolayer adsorption and followed a pseudo-second-order rate equation. The presence of high concentrations of competing Ca2+ and Na+ had no significant effect on the adsorption process. The XPS spectra analyses further indicated that Pb2+ and Cu2+ were adsorbed via the ion exchange of -OH groups. Moreover, HMO-p(HMAm/HEA) could be regenerated by 0.05 mol·L-1 of HCl, and obtained excellent repeated use.