Nomogram predictive models for adult patients with acute lymphoblastic leukaemia based on real-world treatment outcomes.

This study aimed to analyse the characteristics and treatment outcomes of adult patients with acute lymphoblastic leukaemia (ALL) and construct nomogram predictive models for prognosis prediction. Between January 2017 and June 2022, 462 adult patients with ALL were included in this retrospective analysis. Patients' ages ranged from 14 to 84 years. B-cell origin was observed in 82.7% of these patients, while 17.3% of the cases were of T-cell origin. The BCR/ABL1 fusion gene was detected in 32.9% of those with B-ALL. Complete remission was achieved in 83.7% of the patients after induction chemotherapy. The median disease-free survival (DFS) and overall survival (OS) of patients were 19.0 and 39.1 months, respectively. The 5-year DFS and OS rates were 29.5% and 41.8%, respectively. The BCR/ABL1 fusion gene had a significant adverse impact on DFS and OS when patients were treated with tyrosine kinase inhibitors (TKIs) and chemotherapy; however, this effect was eliminated when patients underwent transplantation. Multivariate analysis identified that age ≥ 35 years, white blood cell count ≥ 30 × 109/L, platelet count < 100 × 109/L, failure to achieve complete remission after induction chemotherapy, positive measurable residual disease (MRD), and absence of transplantation were independent adverse prognostic factors for DFS and/or OS. Nomogram predictive models constructed by the rms package in R software based on these prognostic factors demonstrated precise predictive value. In conclusion, adult patients with ALL experience poor survival. TKIs in combination with transplantation can eliminate the adverse effects of BCR/ABL1 fusion genes on prognosis. Nomogram predictive models were accurate for prognostic prediction and will be useful in clinical practice.

Transcriptomic profiling of Poa pratensis L. under treatment of various phytohormones.

Poa pratensis L. (Poaceae) is a valuable grass across the north hemisphere, inhabiting diverse environments with wide altitudinal span, where ubiquitous various kinds of stresses. Phytohormones would be helpful to improve tolerance to abiotic and biotic stresses, but the responses of transcriptome regulation of P. pratensis to exogenous phytohormones application remain unclear. In this study, we explored the alteration of plant physiological responses by the application of phytohormones. Aiming to achieve this knowledge, we got full-length transcriptome data 42.76 Gb, of which 74.9% of transcripts were completed. Then used 27 samples representing four treatments conducted at two time points (1 h and 6 h after application) to generate RNA-seq data. 371 and 907 common DEGs were identified in response to four phytohormones application, respectively, these DEGs were involved in "plant hormone signal transduction", "carbon metabolism" and "plant-pathogen interaction". Finally, P. pratensis basic research can gain valuable information regarding the responses to exogenous application of phytohormones in physiological indicators and transcriptional regulations in order to facilitate the development of new cultivars.

NEDD4-2 and the CLC-2 channel regulate neuronal excitability in the pathogenesis of mesial temporal lobe epilepsy.

An increasing number of studies have focused on the role of NEDD4-2 in regulating neuronal excitability and the mechanism of epilepsy. However, the exact mechanism has not yet been elucidated. Here, we explored the roles of NEDD4-2 and the CLC-2 channel in regulating neuronal excitability and mesial temporal lobe epilepsy (MTLE) pathogenesis. First, chronic MTLE models were induced by lithium-pilocarpine in developmental rats. Coimmunoprecipitation analysis revealed that the interaction between CLC-2 and NEDD4-2. Western blot analyses indicated that NEDD4-2 expression was downregulated, while phosphorylated (P-) NEDD4-2 and CLC-2 expression was upregulated in adult MTLE rats. Then, the primary hippocampal neuronal cells were isolated and cultured, and the NEDD4-2 was knocked down by shRNA vector, resulting in decreased protein levels of CLC-2. While CLC-2 absence caused increased NEDD4-2 in cells. Next, in an epileptic cell model induced by a Mg2+-free culture, whole-cell current-clamp recording demonstrated that NEDD4-2 deficiency inhibited the spontaneous action potentials of cells, and CLC-2 absence caused more significant decrease in the spontaneous action potentials of cells. In conclusion, we herein revealed that NEDD4-2 regulates the expression of CLC-2, which is involved in neuronal excitability, and participates in the pathogenesis of MTLE.

Intra-annual stem radial growth of Qinghai spruce and its environmental drivers in the Qilian Mountains, northwestern China.

Tree stem radial growth could be used to estimate forest productivity, which plays a dominant role in the carbon sink of terrestrial ecosystems. However, it is still obscure how intra-annual stem radial growth is regulated by environmental variables. Here, we monitored Qinghai spruce stem radial growth over seven years and analyzed the environmental drivers of the intra-annual stem radial changes in the Qilian Mountains at low (2700 m) and high altitudes (3200 m). We found that stem radial growth initiated when the daily mean minimum air temperature reached 1.6oC, while the cessation of stem growth was unrelated to temperatures and water conditions. Initiations of stem growth at 2700 m were significantly earlier than that at 3200 m. Maximum growth rates were observed before the summer solstice at low altitude, whereas at high altitude, the majority of them occurred after the summer solstice. Most variability in annual stem increment (AI) can be explained by the rate (Rm) than by the duration of stem growth (∆t), and 78.9 % and 69.6 % of the variability in AI were attributable to Rm for the lower and upper site, respectively. Structural equation modeling revealed that precipitation (P) could both directly positively influence stem radial increment (SRI) and indirectly positively influence SRI through influencing relative humidity (RH), but the positive effect of P on SRI was higher at low altitude than at high altitude. Daily minimum air temperature (Tmin) was also the main direct diver of SRI, and the positive effect of Tmin on SRI was higher at high altitude than at low altitude. Considering the trends in climate warming and humidification over the past decades, climate changes would result in earlier initiation of Qinghai spruce stem growth and promote the growth through positive response to increased precipitation in low altitude and through elevated temperature in high altitude, respectively.

HCN1 pathogenic variants associated with childhood epilepsy in a cohort of Chinese patients.

OBJECTIVE: HCN ion channel family has a widespread expression in neurons, and recently, increasing studies have demonstrated their roles in epilepsies. METHODS: Clinical data of the patients were gathered in a retrospective study. Exon sequencing was used for the patients with unexplained recurrent seizures and varying levels of developmental delay. RESULTS: In this study, eight de novo variants of HCN1 genes were uncovered in eight patients, including six missense variants, one nonsense variant and one frameshift insertion variant; five of them were reported for the first time. The onset age for eight patients ranges from one month to one year. Their main clinical manifestations are epilepsy and varying degrees of developmental delay, and the main type of seizure is focal secondary generalized tonic-clonic seizure. Importantly, in our study, one case presented with a form of migrating focal seizure that has not been reported in the literature. Seizures from five of the eight children were effectively controlled with antiepileptic drugs including valproic acid, levetiracetam and oxcarbazepine. One child developed normally and four children developed mild delay. One child was treated with topiramate, and the convulsion was partially controlled and showed moderate to severe developmental delay. The antiepileptic treatment failed for the other two children, and the two children were treated with sodium valproate, oxcarbazepine, lamotrigine, chlorbazan, levetiracetam and nitrodiazepam successively, but their convulsions were not controlled and showed moderate to severe developmental delay. SIGNIFICANCE: Our research reported eight variants in HCN1 gene causing epilepsy; among these variants, five variants were never reported before. HCN1-related epilepsy usually starts infantile period, and focal secondary generalized tonic-clonic seizure is the most common seizure type. Importantly, we reported the case with migrating focal seizure was rarely reported. Our study expanded both genotype and phenotype for HCN1-related epilepsy.

Mild Synthesis of Polychlorinated Arenes for Efficient Organic Light-emitting Diodes with Dual Thermally Activated Delayed Fluorescence.

Polychlorinated (hetero)arenes have shown great promise for organic optoelectronics applications. However, the harsh synthetic routes for polychlorinated compounds and the possible luminescence quenching from the compact intermolecular π-π stacking induced by chlorine atoms limit their investigations and applications in luminescent materials. Herein, two isomeric polychlorinated polycyclic aromatic hydrocarbon (PAH) compounds JY-1-Cl and JY-2-Cl consisting of rigidified aryl ketones and amine are designed and synthesized under mild conditions through nucleophilic chlorination intermediated by an electron donor-acceptor complex. Among them, as a result of the strong π-π interactions induced by chlorine atoms, JY-2-Cl exhibits bright monomer and dimer emissions with dual thermally activated delayed fluorescence (TADF) characters. Notably, compared with the non-chlorinated compounds, a high photoluminescence quantum yield is maintained after introducing multiple chlorine atoms into JY-2-Cl. The first dual-TADF organic light-emitting diodes are also successfully fabricated with maximum external quantum efficiency as high as 29.1 % by employing JY-2-Cl as emitter. This work presents a new paradigm and synthesis of polychlorinated amine-carbonyl PAHs and demonstrates the great potential of the chlorinated materials for luminescent applications.

Confining donor conformation distributions for efficient thermally activated delayed fluorescence with fast spin-flipping.

Fast spin-flipping is the key to exploit the triplet excitons in thermally activated delayed fluorescence based organic light-emitting diodes toward high efficiency, low efficiency roll-off and long operating lifetime. In common donor-acceptor type thermally activated delayed fluorescence molecules, the distribution of dihedral angles in the film state would have significant influence on the photo-physical properties, which are usually neglected by researches. Herein, we find that the excited state lifetimes of thermally activated delayed fluorescence emitters are subjected to conformation distributions in the host-guest system. Acridine-type flexible donors have a broad conformation distribution or bimodal distribution, in which some conformers feature large singlet-triplet energy gap, leading to long excited state lifetime. Utilization of rigid donors with steric hindrance can restrict the conformation distributions in the film to achieve degenerate singlet and triplet states, which is beneficial to efficient reverse intersystem crossing. Based on this principle, three prototype thermally activated delayed fluorescence emitters with confined conformation distributions are developed, achieving high reverse intersystem crossing rate constants greater than 106 s-1, which enable highly efficient solution-processed organic light-emitting diodes with suppressed efficiency roll-off.

A survey study on early detection of young children with disabilities in urban and rural areas of China.

AIM: This study aimed to understand how children and families access early intervention in China. BACKGROUND: Timely identification and high-quality intervention is expected to prevent and reduce the occurrence and severity of chronic functional impairment for children with disability and is of great significance to individuals and the society. The current study recruited 1129 caregivers of children with disabilities from rural and urban areas of China were recruited to participate in a survey. RESULTS: (a) The first concern about development was raised, usually by the parents, when a child with disabilities was 26 months of age, (b) developmental screening took place 4 months after the first concern and diagnostic evaluation happened 7 months after, (c) the types of early intervention programme varied across urban and rural areas and (d) child and family factors were found associating with age of detection. CONCLUSIONS: Findings highlight the concerningly late age of children being identified for early intervention and disparities in services between urban and rural areas in China. Implications are provided for practitioners, policy makers and future research.

Spermatophore development in drones indicates the metabolite support for sperm storage in honey bees (Apis cerana).

Developing effective long-term sperm storage strategies to maintain activity requires an understanding of the underlying spermatophore developmental phase in drones. Here we compared the developmental processes and metabolites about seminal vesicles of drones from different parentages (0-24 d)in honeybee colonies, including mated queens, virgin queens, and worker bees. The results showed a similar developmental trend of seminal vesicles in thethree groups of drones on the whole, although there were significant differences in developmental levels, as well as in other indicators. Correlation analysis showed significant positive correlations between seminal vesicle width and sperm viability. The metabolomics of the seminal vesicles in drones from mated queens showed differences of the metabolites in each stage. Particularly, squalene identified among them was validated a protective effect on sperm vitality in vitro experiments. Together the results of these assays support that there were significant differences in the developmental levels of seminal vesicles among the three groups of drones in honeybees, wherein a significant correlation between sperm viability and the developmental levels of seminal vesicles were dissected. The metabolomics analysis and semen storage experiments in vitro display signatures of squalene that may act as an effective protective agent in maintaining sperm viability. Collectively, our findings indicate that spermatophore development in drones provides metabolite support, which contributes to research on the differences of sperm viability among drones in the future.

Highly Efficient Purely Organic Phosphorescence Light-Emitting Diodes Employing a Donor-Acceptor Skeleton with a Phenoxaselenine Donor.

Purely organic room-temperature phosphorescence (RTP) materials generally exhibit low phosphorescence quantum yield (ϕP ) and long phosphorescence lifetime (τP ) due to the theoretically spin-forbidden triplet state. Herein, by introducing a donor-acceptor (D-A) skeleton with a phenoxaselenine donor, three nonaromatic amine donor containing compounds with high ϕP and short τP in amorphous films are developed. Besides the enhanced spin-orbit coupling (SOC) by the heavy-atom effect of selenium, the D-A skeleton which facilitates orbital angular momentum change can further boost SOC, and severe nonradiative energy dissipation is also suppressed by the rigid molecular structure. Consequently, a record-high external quantum efficiency of 19.5% are achieved for the RTP organic light-emitting diode (OLED) based on 2-(phenoxaselenin-3-yl)-4,6-diphenyl-1,3,5-triazine (PXSeDRZ). Moreover, voltage-dependent color-tunable emission and single-molecule white emission are also realized. These results shed light on the broad prospects of purely organic phosphorescence materials as highly efficient OLED emitters especially for potential charming lighting applications.

Radial growth of Korshinsk peashrub and its response to drought in different sub-arid climate regions of northwest China.

The increased frequency and intensity of droughts have seriously affected the stability of plantation ecosystems in the Chinese Loess Plateau. Caragana korshinskii Kom. was the dominant afforested shrub species in this region. Evaluating the radial growth of C. korshinskii and its response to drought can provide valuable information for sustainable management of plantations in the context of climate change. In this study, based on 237 shrub C. korshinskii annual ring samples from nine sites in different climate regions, we investigated the response of C. korshinskii radial growth to climate (temperature, precipitation, and monthly resolved standardized precipitation evapotranspiration index (SPEI_01)), and evaluated the differences between them using calculated indices of drought resistance, recovery, and resilience. The results demonstrate that the radial growth of C. korshinskii was mainly limited by drought stress in the previous September in arid regions and in March and June in semi-arid regions, whereas C. korshinskii in semi-humid regions was less influenced by drought stress. Recovery after drought decreased with increasing resistance, and resilience increased significantly with increasing resistance and recovery. Differences in precipitation were found to be the main factor generating variations in shrub resilience; with an increase in precipitation, the recovery and resilience after drought gradually increased. For plantation management, this study suggests that efficient utilization of precipitation resources and site-specific afforestation in different climate and site conditions may help to enhance resilience and improve the ecological service function of plantation forests in the Loess Plateau.

Efficacy and Safety of Belimumab in Patients With Lupus Nephritis: Subgroup Analyses of a Phase 3 Randomized Trial in the East Asian Population.

RATIONALE & OBJECTIVE: Belimumab improved kidney outcomes in patients with active lupus nephritis (LN) in BLISS-LN, leading to its approval in the United States and the European Union. As data on treatment of East Asian patients with LN are limited, we evaluated the efficacy and safety of belimumab in the BLISS-LN East Asian subgroup. STUDY DESIGN: Prespecified subgroup analysis of BLISS-LN, a phase 3, placebo-controlled, randomized 104-week trial. SETTING & PARTICIPANTS: Adults with biopsy-proven, active LN were randomized (1:1) to belimumab or placebo, plus standard therapy. INTERVENTION: Patients were administered intravenous belimumab 10mg/kg, or placebo, plus standard therapy (oral glucocorticoids and either cyclophosphamide for induction followed by azathioprine for maintenance, or mycophenolate mofetil for both induction and maintenance). At the investigator's discretion, 1-3 intravenous pulses of methylprednisolone, 500-1,000mg each, could be administered during induction. OUTCOMES: The primary end point was primary efficacy renal response (PERR; ie, urinary protein-creatinine ratio≤0.7g/g, estimated glomerular filtration rate no more than 20% below preflare value or≥60mL/min/1.73m2, and no treatment failure) at week 104. Key secondary end points included complete renal response (CRR; urinary protein-creatinine ratio<0.5g/g, estimated glomerular filtration rate no more than 10% below preflare value or≥90mL/min/1.73m2, and no treatment failure) at week 104; PERR at week 52; time to kidney-related event or death; and safety. ANALYTICAL APPROACH: PERR and CRR were analyzed using a logistic regression model, and time to a kidney-related event or death was analyzed using a Cox proportional hazards regression model. RESULTS: 142 patients from mainland China, Hong Kong, South Korea, and Taiwan were included (belimumab, n=74; placebo, n=68). At week 104, more belimumab than placebo patients achieved PERR (53% vs 37%; OR, 1.76 [95% CI, 0.88-3.51]) and CRR (35% vs 25%; OR, 1.73 [95% CI, 0.80-3.74]). At week 52, more belimumab than placebo patients achieved PERR (62% vs 37%; OR, 2.74 [95% CI, 1.33-5.64]). Belimumab reduced the risk of a kidney-related event or death compared with placebo at any time (HR, 0.37 [95% CI, 0.15-0.91]). Safety was similar across treatment groups. LIMITATIONS: Small sample size and lack of formal significance testing. CONCLUSIONS: Safety and efficacy profiles were consistent with BLISS-LN overall population, supporting benefits of belimumab treatment in the East Asian subgroup with LN. FUNDING: This study was funded by GSK (GSK study no. BEL114054). TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT01639339.

Ultra-fast triplet-triplet-annihilation-mediated high-lying reverse intersystem crossing triggered by participation of nπ*-featured excited states.

The harvesting of 'hot' triplet excitons through high-lying reverse intersystem crossing mechanism has emerged as a hot research issue in the field of organic light-emitting diodes. However, if high-lying reverse intersystem crossing materials lack the capability to convert 'cold' T1 excitons into singlet ones, the actual maximum exciton utilization efficiency would generally deviate from 100%. Herein, through comparative studies on two naphthalimide-based compounds CzNI and TPANI, we revealed that the 'cold' T1 excitons in high-lying reverse intersystem crossing materials can be utilized effectively through the triplet-triplet annihilation-mediated high-lying reverse intersystem crossing process if they possess certain triplet-triplet upconversion capability. Especially, quite effective triplet-triplet annihilation-mediated high-lying reverse intersystem crossing can be triggered by endowing the high-lying reverse intersystem crossing process with a 3ππ*→1nπ* character. By taking advantage of the permanent orthogonal orbital transition effect of 3ππ*→1nπ*, spin-orbit coupling matrix elements of ca. 10 cm-1 can be acquired, and hence ultra-fast mediated high-lying reverse intersystem crossing process with rate constant over 109 s-1 can be realized.

Tuning Intramolecular Stacking of Rigid Heteroaromatic Compounds for High-Efficiency Deep-Blue Through-Space Charge-Transfer Emission.

A series of ultrapure-blue thermally activated delayed fluorescence (TADF) emitters featuring through-space charge transfer (TSCT) have been constructed by close stacking between the donor and acceptor moieties in rigid heteroaromatic compounds. The obviously accelerated radiative transition of singlet excitons, the diminished vibrionic relaxation of ground and excited states, and the consequent reduced Stokes shift and the narrow emission are evident. The corresponding organic light-emitting diodes (OLEDs) based on AC-BO realize the best performance among all deep-blue TSCT-TADF emitters, with an external quantum efficiency (EQEmax ) of 19.3 %. Furthermore, the OLEDs based on QAC-BO display an EQEmax of 15.8 %, and achieve the first high-efficiency ultrapure-blue TSCT-TADF material with an excellent Commission Internationale de L'Eclairage coordinate (CIE) of (0.145, 0.076) which perfectly matches the ultrapure-blue CIE requirements (0.14, 0.08) defined by the National Television System Committee.

[Responses of radial growth of Juniperus przewalskii to different droughts over the northeastern Tibetan Plateau, China]. / 青藏高原东北部祁连圆柏径向生长对不同类型干旱的响应.

To study the responses of radial growth of Juniperus przewalskii to climate factors of the different periods (pre-growing season (February-April), growing season (May-July)), and the vulnerability (resistance, RT; recovery, RC) of J. przewalskii to different drought events (precipitation, temperature and the both caused), we used tree ring width data of J. przewalskii from 17 sampling sites across the northeastern Tibetan Plateau to analyze the correlation between radial growth and climate factors of different periods, and the vulnerability in different drought events. The results showed that radial growth of J. przewalskii had significant positive correlation with drought index and negative correlation with temperature in the growing season (P<0.1). The vulnerability of J. przewalskii to drought events of different periods had significant difference. In the pre-growing season drought events, the RT of J. przewalskii at low altitude was 2.3% higher than that at high altitude, the RC of J. przewalskii at low altitude was 25.1% lower than that at high altitude. For drought events in the growing season, the RT of J. przewalskii at low altitude was 23.7% lower than that at high altitude, the RC of J. przewalskii at low altitude was 107.1% higher than that at high altitude. The mean RC(1.68) of J. przewalskii in precipitation-caused drought events was strong, while the mean RT(1.43) of J. przewalskii in temperature-caused drought events was strong. The growth of J. przewalskii, especially for that at low altitude, would be largely limited by drought caused by global warming in the future.

Molecular Engineering of Sulfur-Bridged Polycyclic Emitters Towards Tunable TADF and RTP Electroluminescence.

Highly efficient organic thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) emitters for organic light-emitting diodes (OLEDs) generally consist of a twisted donor-acceptor skeleton with aromatic amine donors. Herein, through introducing sulfur atoms into isomeric pentaphene and pentacene frameworks, we demonstrate a set of polycyclic luminophores exhibiting efficient TADF and RTP characters. The incorporation of sulfur atoms confirms a folded molecular plane, while intensifies singlet-triplet spin-orbit coupling. Further, the isomeric effect has a significant effect on the electronic structure of excited state, giving rise to the investigated compounds tunable luminescence mechanisms of TADF and RTP. With efficient triplet harvesting ability, maximum external quantum efficiencies up to 25.1 % and 8.7 % are achieved for the corresponding TADF and RTP OLEDs, verifying the great potential of sulfur-bridged frameworks for highly efficient devices.

Asymmetric Thermally Activated Delayed Fluorescence Emitter for Highly Efficient Red/Near-Infrared Organic Light-Emitting Diodes.

Developing highly efficient red/near-infrared thermally activated delayed fluorescence (TADF) materials is of great importance for organic light-emitting diodes (OLEDs). Here, we reported an asymmetric TADF emitter (TCPQ), which exhibits a high reverse intersystem crossing rate as well as a low non-radiative rate due to molecular symmetry breaking through multiple donor substitution. The coexistence of multiple donors endows TCPQ with not only near-infrared emission but also excellent device performances. As for the TCPQ-based OLEDs, the 10 and 20 wt % doped devices exhibit outstanding external quantum efficiencies (EQEs) of 21.9 and 19.2% with red emission peaks at 612 and 642 nm, respectively. Meanwhile, the non-doped device achieves an EQE of 5.4% with an emission peak at 718 nm, showing near-infrared emission. These device efficiencies are among the best performances of red/near-infrared TADF-OLEDs, demonstrating that the asymmetry design is a potential strategy for constructing long wavelength TADF materials with high efficiency.

Abnormal Antennal Olfactory Sensilla Phenotypes Involved in Olfactory Deficit in Bactrocera correcta (Diptera: Tephritidae).

The guava fruit fly, Bactrocera correcta, is one of the most destructive pests in the genus Bactrocera and detects environmental odorants mainly through antennal olfactory sensilla phenotypes with nanopores. However, it is unclear whether there are naturally occurring abnormal antennal olfactory sensilla phenotypes that affect olfaction. Here, we found that there were abnormal bulges besides nanopores on the surface of trichoid and basiconic olfactory sensilla in the antennal flagellum of long-term laboratory rearing colony (LTC), and that nanopore number in these olfactory sensilla was also remarkably reduced. Notably, the electroantennogram (EAG) responses of LTC insects to methyl eugenol or ß-caryophyllene were inhibited, and their behavioral responses elicited by the same odorants were also impaired. These results revealed naturally occurring abnormal antennal olfactory sensilla phenotypes which were involved in olfactory deficit in B. correcta, providing a platform to further study nanopore-targeted pest control technologies in the future.

A "Flexible" Purely Organic Molecule Exhibiting Strong Spin-Orbital Coupling: Toward Nondoped Room-Temperature Phosphorescence OLEDs.

Purely organic materials usually exhibit weak spin-orbital coupling (SOC) effect because of the lack of noble heavy metals, and the generation and direct emission from the triplet state is spin-forbidden. This would lead to slow intersystem crossing, long triplet lifetime, and low phosphorescence quantum yield. Herein, strong spin-orbital coupling between singlet and triplet was observed in a "flexible" and twist thianthrene-pyrimidine-based purely organic compound in an amorphous film state, which shows a fast intersystem crossing process and a high phosphorescence rate of 1.1 × 103 s-1. The heavy atom sulfur and nitrogen atoms in the molecule can provide n-π* transition character for efficient spin-orbital coupling. Moreover, the flexible molecule skeleton enables conformational change and molecular vibration in excited states, which was proved to be vital for efficient vibrational spin-orbital coupling. Benefitting from the strong SOC effect, a nondoped purely organic phosphorescence light-emitting diode was fabricated, which achieves a maximum external quantum efficiency of 7.98%, corresponding to an exciton utilization ratio exceeding 87.6%.

Constructing Organic Electroluminescent Material with Very High Color Purity and Efficiency Based on Polycyclization of the Multiple Resonance Parent Core.

Multiple resonance thermally activated delayed fluorescence (MR-TADF) compounds have set off an upsurge of research because of their tremendous application prospects in the field of wide color gamut display. Herein, we propose a novel MR-TADF molecular construction paradigm based on polycyclization of the multiple resonance parent core, and construct a representative multiple resonance polycyclic aromatic hydrocarbon (MR-PAH) based on the para-alignment of boron and nitrogen atoms into a six-membered ring (p-BNR). Through the retrosynthesis analysis, a concise synthesis strategy with wide applicability has been proposed, encompassing programmed sequential boron esterification, Suzuki coupling and Scholl oxidative coupling. The target model molecule BN-TP shows green fluorescence with an emission peak at 523 nm and a narrow full-width at half-maximum (FWHM) of 34 nm. The organic light-emitting diode (OLED) employing BN-TP as an emitter exhibits ultrapure green emission with Commission Internationale de L'Eclairage (CIE) coordinates of (0.26, 0.70), and achieves a maximum external quantum efficiency (EQE) of 35.1 %.