Enhancing operational stability of OLEDs based on subatomic modified thermally activated delayed fluorescence compounds.

The realization of operationally stable blue organic light-emitting diodes is a challenging issue across the field. While device optimization has been a focus to effectively prolong device lifetime, strategies based on molecular engineering of chemical structures, particularly at the subatomic level, remains little. Herein, we explore the effect of targeted deuteration on donor and/or acceptor units of thermally activated delayed fluorescence emitters and investigate the structure-property relationship between intrinsic molecular stability, based on isotopic effect, and device operational stability. We show that the deuteration of the acceptor unit is critical to enhance the photostability of thermally activated delayed fluorescence compounds and hence device lifetime in addition to that of the donor units, which is commonly neglected due to the limited availability and synthetic complexity of deuterated acceptors. Based on these isotopic analogues, we observe a gradual increase in the device operational stability and achieve the long-lifetime time to 90% of the initial luminance of 23.4 h at the luminance of 1000 cd m-2 for thermally activated delayed fluorescence-sensitized organic light-emitting diodes. We anticipate our strategic deuteration approach provides insights and demonstrates the importance on structural modification materials at a subatomic level towards prolonging the device operational stability.

Fine Emission Tuning from Near-Ultraviolet to Saturated Blue with Rationally Designed Carbene-Based [3 + 2 + 1] Iridium(III) Complexes.

We designed and synthesized a new class of six phosphorescent [3 + 2 + 1] iridium(III) complexes [(pbib)Ir(C^C)CN] bearing a tridentate 1,3-bis(1-butylimidazolin-2-ylidene) phenyl N-heterocyclic carbene (NHC)-based pincer ligand (pbib), bidentate imidazole-based NHC ligands (C^C), and a monodentate cyano group and investigated their photophysical, electrochemical, and thermal stabilities and electroluminescent properties. The extended π-conjugation of the imidazole-based C^C ligand is found to be the key to fine-tune the emission energies from ultraviolet blue (λ = 378 nm) to saturated blue (λ = 482 nm), as shown by electrochemical and photophysical studies, which is also revealed by the density functional theory (DFT) and time-dependent DFT calculations. Vacuum-deposited organic light-emitting diode devices have been fabricated with these newly synthesized emitters and exhibited the best external quantum efficiency of 6.4% and Commission International de L'Éclairage (CIE) coordinates of (0.163, 0.096), where the CIE y is very similar to the National Television System Committee standard blue CIE (x, y) coordinates of (0.149, 0.085). These results indicate that the novel [3 + 2 + 1] coordinated iridium(III) complexes [(pbib)Ir(C^C)CN], having a saturated blue emission, not only could alleviate the photodegradation of the emitters when compared to [(pbib)Ir(pmi)CN] but also provide new design strategies of saturated-blue-emitting iridium(III) complexes.

[Study on effect of SuperTab 40LL on compression characteristics of musk sustained-release mini-tablets based on mathematical models].

In this paper, co-processed lactose SuperTab 40 LL was selected as fillers to study the preparation of musk sustained-release mini-tablets in the Xihuang multiple-unit drug release system. Musk sustained-release tablets containing different proportions of SuperTab 40 LL and MCC were prepared under various pressures, and then the compressibility and compactibility of these prescriptions were evaluated by Walker, Heckel and Ryshkewitch-Duckworth equations. In addition, the fluidity of the prescriptions was evaluated by parameters of Kawakita equation. There was a comprehensive analysis of the effect of SuperTab 40 LL on musk sustained-release mini-tablets combined with the appearance of SuperTab 40 LL and their tensile strength. The results shown that SuperTab 40 LL had better compression process through the Heckel equation, and the direct compression process of drug powders with excipients can be analyzed by the Kawakita and Ryshkewitch-Duckworth equations. As a new type of co-processed lactose, SuperTab 40 LL had a good fluidity and compactibility. SuperTab 40 LL may undergo particle crushing and plastic deformation during the compression process, which increased the contact area and bonding sites between the particles, and aggregated and shaped the mixed powder easy. Moreover, MCC showed a synergistic effect, and the combined application with SuperTab 40 ll could effectively improve the fluidity and compressibility of the musk sustained-release powder. When the ratio of SuperTab 40 LL and MCC was 2∶1, musk sustained-release mini-tablets had a high drug loading capacity and good compactibility in line with the design objectives.

Highly Efficient Phosphorescent Blue-Emitting [3+2+1] Coordinated Iridium (III) Complex for OLED Application.

Cyclometalated iridium (III) complexes are indispensable in the field of phosphorescent organic light-emitting diodes (PhOLEDs), while the improvement of blue iridium (III) complexes is as yet limited and challenging. More diversified blue emitters are needed to break through the bottleneck of the industry. Hence, a novel [3+2+1] coordinated iridium (III) complex (noted as Ir-dfpMepy-CN) bearing tridentate bis-N-heterocyclic carbene (NHC) chelate (2,6-bisimidazolylidene benzene), bidentate chelates 2-(2,4-difluorophenyl)-4-methylpyridine (dfpMepy), and monodentate ligand (-CN) has been designed and synthesized. The tridentate bis-NHC ligand enhances molecular stability by forming strong bonds with the center iridium atom. The electron-withdrawing groups in the bidentate ligand (dfpMepy) and monodentate ligand (-CN) ameliorate the stability of the HOMO levels. Ir-dfpMepy-CN shows photoluminescence peaks of 440 and 466 nm with a high quantum efficiency of 84 ± 5%. Additionally, the HATCN (10 nm)/TAPC (40 nm)/TcTa (10 nm)/10 wt% Ir-dfpMepy-CN in DPEPO (10 nm)/TmPyPB (40 nm)/Liq (2.5 nm)/Al (100 nm) OLED device employing the complex shows a CIE coordinate of (0.16, 0.17), reaching a deeper blue emission. The high quantum efficiency is attributed to rapid singlet to triplet charge transfer transition of 0.9-1.2 ps. The successful synthesis of Ir-dfpMepy-CN has opened a new window to develop advanced blue emitters and dopant alternatives for future efficient blue PhOLEDs.

Phosphorescent [3 + 2 + 1] coordinated Ir(iii) cyano complexes for achieving efficient phosphors and their application in OLED devices.

A series of neutral [3 + 2 + 1] coordinated iridium complexes bearing tridentate bis-NHC carbene chelates (2,6-bisimidazolylidene benzene), bidentate chelates (C^N ligands, e.g. derivatives of 2-phenylpridine), and monodentate ions (halides and pseudo-halides, such as Br, I, OCN and CN ions) have been systematically designed and synthesized. X-ray single crystal structure characterization revealed that the nitrogen atom in C^N ligands is located trans to the carbon atom in the benzene ring in tridentate chelates, while the coordinating carbon atom in C^N ligands is located trans to the monodentate ligands. Photophysical studies reveal that the C^N ligands play a vital role in tuning the UV absorption and emission properties, while the tridentate bis-NHC carbene chelates influence the lowest absorption band and emission energy when compared to heteroleptic Ir(ppy)2(acac) [i.e. molar absorptivities at ∼450 nm for ppy-OCN and Ir(ppy)2(acac) are 350 M-1 cm-1 and 1520 M-1 cm-1 and emission maximum peaks are at 465 nm and 515 nm respectively]. Among monodentate ligands that the complexes bear, the group containing the cyanide ligand displays higher emission energy, higher photophysical quantum yields, longer triplet lifetimes and better electrochemical and thermal stabilities than those of cyanate and bromide. Particularly, a blue organic light-emitting diode (OLED) based on dfppy-CN exhibited a maximum external quantum efficiency of 22.94% with CIE coordinates of (0.14, 0.24). Furthermore, a small efficiency roll-off of 5.7% was observed for this device at 1000 cd m-2.

Exploring the Potential of Mesoporous Silica as a Carrier for Puerarin: Characterization, Physical Stability, and In Vivo Pharmacokinetics.

The aim of this study was to evaluate the use of a novel porous silica carrier, AEROPERL® 300 Pharma (AP), to improve the in vitro release and oral bioavailability of puerarin (PUE) in solid dispersions (SDs). PUE-AP SD formulations with different ratios of drug to silica (RDS) were prepared by the solvent method. The scanning electron microscopy (SEM) results indicated that the dispersion of PUE improved as the concentration of AP was increased. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results revealed that PUE mostly existed in an amorphous state in the SDs. The rate of drug dissolution from the SDs was significantly higher than that from the PUE powder (p < 0.05). The in vitro drug release percentage from the PUE-AP SDs increased as the RDS was reduced. The oral bioavailability of PUE from the SDs improved when using AP, as indicated by AUC(0-∞), which was 2.05 and 2.01 times greater than that of the PUE (API) and PVP K30 SDs, respectively (p < 0.05). The drug content, in vitro release profiles, and the amorphous state of PUE in the PUE-AP SDs showed no significant changes after being stored at room temperature for 6 months or under accelerated conditions (40 ± 2°C, 75 ± 5% relative humidity) for 3 months. AP has a high pore volume, large specific surface area, excellent flowability, and hydrophilic properties, making it capable of improving the dissolution and bioavailability of poorly water-soluble drugs.

Curcumin-loaded redox-responsive mesoporous silica nanoparticles for targeted breast cancer therapy.

HYPOTHESIS: The antitumor applications of curcumin (CUR) are limited because of its low water solubility, poor stability, and low bioavailability. We developed novel nanocarrier systems for tumour targeting and controlled CUR release and evaluated their therapeutic efficacy. EXPERIMENTS: The surface of mesoporous silica nanoparticles (MSN) was modified with hyaluronan (HA) or polyethyleneimine-folic acid (PEI-FA) via disulfide bonds. The capacity of the resultant nanocarriers (MSN-HA and MSN-PEI-FA, respectively) for CUR delivery was evaluated in a breast cancer cell line and a mouse xenograft model. FINDINGS: MSN/CUR-PEI-FA and MSN/CUR-HA were cytotoxic to MDA-MB-231 breast cancer cells. Both formulations showed an enhanced cellular uptake compared with that of a non-targeted nanocarrier, with a greater cellular uptake of FA-modified nanoparticles than that of HA-modified nanoparticles. Accordingly, MSN-PEI-FA showed more precise targeting and higher accumulation in tumours than did MSN-HA, as visualized by live imaging. Both types of nanoparticles had good biocompatibility and low toxicity, and MSN/CUR-PEI-FA inhibited the tumour growth to a greater degree than did free CUR. Thus, MSN/CUR-PEI-FA are a promising drug delivery system for the treatment of breast cancer.

Probe-free real-time reverse transcription polymerase chain reaction assays for the detection and typing of porcine reproductive and respiratory syndrome virus in Canada.

Porcine reproductive and respiratory syndrome (PRRS) has tremendous impact on the pork industry in North America. The molecular diagnosis of infection with PRRS virus (PRRSV) is hampered by its considerable strain diversity. In this study, 43 previously published or newly developed primers for probe-free real-time reverse transcription polymerase chain reaction (RT-PCR) were evaluated on their sensitivity, specificity, reproducibility, and repeatability, using a diverse panel of 36 PRRSV strains as well as other arteriviruses and unrelated porcine viruses. Three primer pairs had excellent diagnostic and analytical sensitivity on par with a probe-based reference assay, absolute specificity to virus genotype and species, as well as over 95% reproducibility and repeatability across a wide dynamic range.

Le syndrome dysgénésique et respiratoire du porc (SDRP) a un impact énorme sur l'industrie du porc en l'Amérique du Nord. Le diagnostic moléculaire de l'infection avec le virus du SDRP est entravée par sa diversité considérable. Dans cette étude, 43 amorces publiées antérieurement ou nouvellement développés pour RT-PCR en temps réel sans d'une sonde spécifique ont été évalués sur leur sensibilité, la spécificité, la reproductibilité et la répétabilité. Un groupe varié de 36 souches de virus du SDRP, d'autres virus appartenant au genre des arterivirus et les virus porcins indépendants a été utilisé. Trois paires d'amorces ont une excellente sensibilité de diagnostic and d'analyse qui équivaut à un test de référence basé sur des sondes. Ils avaient une spécificité absolue de génotype et des espèces du virus, et la reproductibilité et la répétabilité a été plus de 95 % sur une large plage dynamique.(Traduit par les auteurs).