Two tetradentate Pt­(II) complexes with peripheral bulky-group hindrances [Pt­(pzpyOczpy-B1) and Pt­(pzpyOczpy-B2)] were synthesized and fully investigated for their structural and blue phosphorescent properties. Both X-ray crystallography and computational simulation revealed that bulky substituents incorporated into the C-pyrazolyl and C-pyridinyl positions lie out of the cyclometallated plane, thus alleviating the intramolecular distortions as well as reducing the intermolecular interaction in the solid state. In dichloromethane, their emission peaks at 460 nm with a narrow full width at half-maximum (FWHM) of less than 50 nm, and the photoluminescent quantum yields are over 95% with short decay lifetimes (<5 μs). Solution-processed blue devices are fabricated based on the two complexes. Device A based on Pt­(pzpyOczpy-B1) shows excellent electroluminescent performances with the maximum current efficiency, power efficiency, and external quantum efficiency of 47.0 cd/A, 24.6 lm/W, and 22.9%, respectively. The understanding on inert peripheral hindrances provides an effective approach to designing Pt­(II) complexes for high-quality blue phosphorescent emitters.

Described herein is a stable complex, Pt(mpzpyOczpy-mesi), embodying efficient, narrow blue emission. The highly twisted structure of the complex improves the stability and efficiency of photo-and electroluminescence by reducing the intermolecular interactions. The complex in solution shows high photoluminescence efficiency (>95%) and radiative decay rate (K r = 2.9 × 10 5 s −1 ) with a narrow emission spectrum. The bottom-emitting phosphorescent device, BE1, exhibits durable deep blue emission with CIE coordinates of (0.145, 0.166) and 5.2 h of LT 50 at an initial luminance of 685 cd/m 2 . Top-emitting devices, TE1 and TE2, achieve ultrapure blue color with CIE x,y values of (0.141, 0.068) and (0.140, 0.071), respectively. TE4 shows high brightness of 3405 cd m −2 at 50 mA m −2 , EQE of 10.2% at 1000 cd/m 2 , and almost negligible color deviation around (0.135, 0.096) at viewing angles of 0°−60°.

In this report, a solution-processable cohost system incorporating N,N′-di(naphtalene-1-yl)-N,N′-diphenylbenzidine (NPB) and Csp 3 -annulated phenylquinoline derivatives, including spiro, is developed for highly efficient saturated red phosphorescent organic light emitting diodes (OLEDs). IAIQ, PAIQ, and m-TPA-DPIQ, designed with the increase of molecular flexibility, are systematically investigated. Solution-processable devices based on the efficient phosphorescent emitter bis[2-(3,5-dimethylphenyl)isoquinolinato](2,8-dimethyl-4,6nonanedionato)Iridium [Ir(mpiq) 2 divm] are successfully fabricated, and give electroluminescent peaks at 634−636 nm with Commission Internationale de L'Eclairage coordinates of (0.70, 0.30). Under optimized conditions, the devices incorporating IAIQ, PAIQ, and m-TPA-DPIQ exhibit high external quantum efficiency with the maximum value at 25.1%, 23.4%, and 23.3%, respectively, and all exceeding 18% at the luminance of 1000 cd/m 2 . In application, the supersaturated red devices with excellent performance could facilitate the development of wet-made displays. The newly developed Csp 3 -annulated host materials with their excitonic properties also showoff the tactic to construct cohost system for high-quality phosphorescent OLEDs.

Two novel Pt­(II) complexes of type Pt­[N̂C–O–C′̂N′], Pt­(pzpyOppz-A) and Pt­(pzpyOppz-B), were developed for excimer-based emissions. N̂C and N′̂C′ are the motifs of substituted pyrazolyl-pyridyl (pzpy) and phenyl-pyrazolyl (ppz), respectively. The complexes can readily form dimers in a solid matrix, resulting in an excimer-based emission with high photoluminescence efficiency. By utilizing dual emission bands corresponding to the monomer and excimer, efficient phosphorescent organic light-emitting diodes (PhOLEDs) with a broad spectral emission were fabricated. The device employing Pt­(pzpyOppz-A) achieves a broad yellowish-white emission with a full width at half-maximum of 152 nm at 3 wt % concentration and maximum external quantum efficiency (EQE), power efficiency (PE), and current efficiency (CE) of 20.7%, 43.9 Lm W–1, and 60.1 cd A–1, respectively, at a 5 wt % concentration. The device with 40 wt % Pt­(pzpyOppz-B) therein exhibits an exclusive excimer-based emission with the maximum EQE, PE, and CE of 25.5%, 55.5 Lm W–1, and 62.3 cd A–1, respectively. This work shows the molecular art of the Pt­(II) complex for highly performable phosphorescent devices via utilizing the in-situ-formed dimer in a simplified architecture.

Sleep deprivation impairs learning and memory. The neuroprotective function of ginsenoside Rg1 (Rg1) has been reported. This study aimed to investigate the alleviative effect and underlying mechanism of action of Rg1 on learning and memory deficits induced by sleep deprivation. Using 72 h of LED light to establish sleep deprivation model and treatment with Rg1-L (0.5 mg/ml), Rg1-H (1 mg/ml), and melatonin (positive control, 0.25 mg/ml), we investigated the behavioral performance of sleep deprivation zebrafish through 24 h autonomous movement tracking, a novel tank diving test, and a T-maze test. Brain injuries and ultrastructural changes were observed, brain water content was measured, and apoptotic events were analyzed using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining. The oxidation-associated biomarkers superoxide dismutase, catalase, and glutathione peroxidase activity and lipid peroxidation product malondialdehyde content were detected. Real-time PCR and western blotting were performed to detect the levels of apoptotic molecules (Bax, caspase-3, and Bcl-2). Rg1-treatment was observed to improve the behavioral performance of sleep-deprivation fish, alleviate brain impairment, and increase oxidative stress-related enzyme activity. Rg1 can effectively exhibit neuroprotective functions and improve learning and memory impairments caused by sleep deprivation, which could be mediated by the Bcl-2/Bax/caspase-3 apoptotic signaling pathway (see Supplementary Video Abstract, Supplemental digital content, http://links.lww.com/WNR/A702 which demonstrates our research objectives, introduction overview of Rg1, and main direction of future research).