Colloidal all‐inorganic perovskites nanocrystals (NCs) have emerged as a promising material for display and lighting due to their excellent optical properties. However, blue emissive NCs usually ...suffer from low photoluminescence quantum yields (PLQYs) and poor stability, rendering them the bottleneck for full‐color all‐perovskite optoelectronic applications. Herein, a facile approach is reported to enhance the emission efficiency and stability of blue emissive perovskite nano‐structures via surface passivation with potassium bromide. By adding potassium oleate and excess PbBr2 to the perovskite precursor solutions, potassium bromide‐passivated (KBr‐passivated) blue‐emitting (≈450 nm) CsPbBr3 nanoplatelets (NPLs) is successfully synthesized with a respectably high PLQY of 87%. In sharp contrast to most reported perovskite NPLs, no shifting in emission wavelength is observed in these passivated NPLs even after prolonged exposures to intense irradiations and elevated temperature, clearly revealing their excellent photo‐ and thermal‐stabilities. The enhancements are attributed to the formation of K‐Br bonding on the surface which suppresses ion migration and formation of Br‐vacancies, thus improving both the PL emission and stability of CsPbBr3 NPLs. Furthermore, all‐perovskite white light‐emitting diodes (WLEDs) are successfully constructed, suggesting that the proposed KBr‐passivated strategy can promote the development of the perovskite family for a wider range of optoelectronic applications.
High‐quality blue‐emitting CsPbBr3 nanoplatelets (NPLs) are synthesized via a facile potassium bromide‐enriched surface passivation. The resultant blue‐emitting (≈450 nm) CsPbBr3 NPLs show a high PLQY of 87% with excellent thermal stability and photostability. Furthermore, white light LEDs based on the mixture perovskite materials including the blue‐emitting NPLs are constructed, demonstrating a wide color gamut.
Eight bidentate NHC/Ru complexes, namely
Ru-1-Ru-8
, were designed and prepared. In particular,
Ru-2
displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols ...and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
A highly active and robust bidentate NHC/Ru complex for the acceptorless dehydrogenative coupling of alcohols and hydroxides in open air.
The direct amide synthesis from alcohols and amines applying various transition metal catalysts has been demonstrated as an attractive and promising process. Among various catalytic systems, ...N-heterocyclic carbene (NHC)-based ruthenium (Ru) ones have been testified to be active for this atom-economic transformation. Although a variety of imidazole-based NHC/Ru catalytic systems were reported to be active for this reaction, the benzimidazole-based analogs exhibited higher catalytic performance in most cases. However, these catalytic systems, which comprise a monodentate NHC ligand and a Cl or phosphine ligand as the key components, require relatively high catalyst loadings. In order to obtain more active and robust catalytic systems, we aim to bridge two monodentate ligands with one bidentate NHC ligand. Therefore, a number of CNHCC bidentate NHC precursors were designed and synthesized. Through screening of the NHC precursors and other reaction conditions, potent and phosphine-free bidentate NHC/Ru catalytic systems were discovered for the efficient amide synthesis. Interestingly, from the in situ generated catalytic system, two NHC/Ru intermediates were isolated and structurally confirmed by X-ray crystallography. Notably, these two complexes are active for the amide synthesis even at a low catalyst loading of 0.5 mol%, which could verify that they should be key intermediates during the catalysis. Probably, the current catalytic systems, featuring high efficiency and ready accessibility, could be valuable for more interesting applications.
2-Aminobenzothiazoles comprise a valuable structural motif, which prevails in versatile natural products and biologically active compounds. Herein, a switchable and scalable C–N coupling protocol was ...developed for the synthesis of these compounds from 2-chlorobenzothiazoles and primary amines. Gratifyingly, this protocol was achieved under transition-metal-free and solvent-free conditions. Moreover, introducing an appropriate amount of NaH completely switched the selectivity from mono- toward di-heteroarylation, and further investigations provided a rationale for this new finding. Furthermore, gram-scale synthesis of representative products 3a and 4a was realized by applying operationally simple and glovebox-free procedures, which revealed the practical usefulness of this work. Finally, evaluation of the quantitative green metrics provided evidence that our protocol was superior over the literature ones in terms of green chemistry and sustainability.
•Overcome the aggregation-induced quenching effect of CDs in solid state.•A novel white light-emitting nanocomposite with a core–shell structure has been synthesized.•A UV-pumped WLED with a CRI up ...to 91 has been fabricated with the nanocomposite.•Controllable blue/yellow PL intensity ratios of the prepared nanocomposite.
As a promising energy-saving technique, the eco-friendly and low-cost solid-state white light-emitting diodes (WLEDs) based on quantum dots (QDs) have been widely studied. Herein, a WLED device prepared by core–shell structure nanocomposites based on Ag-In-S/ZnS@SiO2 quantum dots (AIS@SiO2) and carbon quantum dots (CDs) was successfully constructed. CDs were combined onto the surface of AIS@SiO2 QDs to synthesize Ag-In-S/ZnS@SiO2-Carbon quantum dots (AIS-CDs) nanocomposites with a white-light emission, which successfully overcome the quenching effect of CDs induced by conventional aggregation. The as-prepared AIS-CDs nanocomposites presented high stability and a photoluminescence quantum yield (PLQY) of 35%. Moreover, the corresponding AIS-CDs nanocomposites-based WLEDs demonstrated the color coordinate of (0.32, 0.33), which is comparable to the pure white light (0.33, 0.33); furthermore, the luminous efficiency of the as-prepared WLEDs showed 15.1 lm W−1. These results reported herein may open up a new avenue for the development of high-performance, low-cost, and environmentally-friendly WLEDs.
Abstract Nonviral magnetofection facilitates gene transfer by using a magnetic field to concentrate magnetic nanoparticle-associated plasmid delivery vectors onto target cells. In light of the ...well-established effects of the Tat peptide, a cationic cell-penetrating peptide, that enhances the cytoplasmic delivery of a variety of cargos, we tested whether the combined use of magnetofection and Tat-mediated intracellular delivery would improve transfection efficiency. Through electrostatic interaction, gene transfer complexes were generated by mixing polyethylenimine-coated cationic magnetic iron beads with plasmid DNA, followed by addition of a bis(cysteinyl) histidine-rich Tat peptide. These ternary magnetofection complexes provided a 4-fold improvement in transgene expression at a dose of 1 μg of plasmid DNA per 20,000 cells over the binary complexes without the Tat peptide and transfected up to 60% of cells in vitro . The enhanced transfection efficiency was also observed in vivo in the rat spinal cord after lumbar intrathecal injection. Moreover, the injected ternary magnetofection complexes in the cerebrospinal fluid responded to a moving magnetic filed by shifting away from the injection site and mediating transgene expression in a remote region. Thus, our approach could potentially be useful for effective gene therapy treatments of localized diseases.
No method is available to predict whether patients with patent ductus arteriosus (PDA) and severe pulmonary arterial hypertension (PAH) will show persistent postprocedural PAH (PP-PAH) after PDA ...closure. This study evaluated the usefulness of trial occlusion for predicting PP-PAH after transcatheter PDA closure in patients with severe PAH.
Trial occlusion was performed in 137 patients (age ≥12 years) with PDA and severe PAH. All patients undergoing trial occlusion had a mean pulmonary artery pressure ≥45 mm Hg, pulmonary:systemic flow (Qp/Qs) ratio >1.5, and pulmonary:systemic resistance (Rp/Rs) ratio <0.7. A total of 135 patients (98%) showing stable hemodynamics during occlusion trial underwent successful device closure. Linear correlation analysis revealed weak or moderate relationships between the baseline and post-trial pulmonary artery pressures and pulmonary:systemic pressure (Pp/Ps) ratios. Patients were followed up for 1 to 10 years (median: 5 years). PP-PAH (systolic pulmonary artery pressure >50 mm Hg by Doppler echocardiography) was detected in 17 patients (13%), who displayed no significant differences in sex and age compared with patients without PP-PAH. According to discriminant analysis, the strongest discriminators between patients with and without PP-PAH were the baseline left ventricular end-diastolic volume and the baseline and post-trial systolic Pp/Ps ratios. In particular, a post-trial systolic Pp/Ps ratio >0.5 correctly classified 100% of the PP-PAH and non-PAH patients.
Trial occlusion is a feasible method to predict PP-PAH in patients with PDA and severe PAH. A post-trial systolic Pp/Ps ratio >0.5 indicates a high risk of PP-PAH occurrence after device closure.
Abstract Background Detection of pulmonary vasoreactivity is important for the evaluation of patient with pulmonary arterial hypertension (PAH). The present study aimed to investigate the acute ...hemodynamic responses to adenosine and iloprost in patients with congenital heart defects (CHDs) and severe PAH. Patients and methods From Mar 2007 to Nov 2009, 75 patients with severe PAH secondary to left-to-right shunt CHDs underwent acute vasodilator test using aerosolized iloprost ( n = 50) or intravenous adenosine ( n = 25). The hemodynamics were detected and analyzed. Results Decreased mean pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR) were observed in 39 and 43 patients in the iloprost group, and in 16 and 19 patients in the adenosine group, respectively. However, the mean PAP was higher than 40 mm Hg in both groups. No significant difference was observed in the age and baseline hemodynamics between the patients with the decrease of PVR and mean pulmonary-to-aortic pressure (Pp/Ps) ratio greater than 10% and the remaining patients. Adenosine decreased both PAP and systemic arterial pressure significantly, while iloprost inhalation selectively reduced the PAP and increased the oxygen saturation of femoral arterial blood and the pulmonary-to-systemic flow (Qp/Qs) ratio. Compared with adenosine, iloprost caused a more profound decline in the Pp/Ps ratio, PVR and pulmonary-to-systemic vascular resistance ratio, and increase in the Qp/Qs ratio. Conclusions The acute haemodynamic responses to adenosine and iloprost varied among the patients with CHDs and severe PAH. Different to adenosine, inhaled iloprost exerted selective pulmonary vasodilative effects and was beneficial for pulmonary gas exchange.
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