Synthesis and properties of binaphthyl chiral thermally activated delayed fluorescence molecules using thioxanthone as acceptor

The currently reported axial chiral molecules based on the 3,3'-substitution of the binaphthyl skeleton are limited by intrinsic fluorescence properties,resulting in generally low device efficiencies(EQE<5%)of related organic light emitting diodes(OLEDs).Herein,we designed and synthesized four pair of chiral binaphthyl enantiomers(R/S-1-R/S-4)adopting acceptor-donor-donor-acceptor(ADDA)structure by introducing different thioxanthone modification groups on the 3,3'-position of 2,2'-dimethoxy-1,1'-binaphthalene.Among them,emitter R/S-2 and R/S-4 obtained by enhancing intramolecular charge transfer exhibited TADF characteristics due to relatively small Est of 0.12eV and 0.17eV,and relatively moderate SOC matrix elements of 0.28 cm^(-1)and 0.10 cm^(-1)between the 1CT and 3LE states.The CD spectra of these enantiomers in diluted solutions showed perfect mirror images and reasonable gabs for small organic molecules(10^(-4)-10^(-3)).And the external quantum eficiencies(EQE)of 10.9%and 8.32%for device A and B based on emitter S-2 and S-4 were highest compared with currently reported axial chiral molecules based on the 3,3'-position substitution of binaphthyl skeleton,providing simple molecular design strategies to construct efficient CP-OLED device.

A single mutation in the PBC loop of VP2 is involved in the in vitro replication of infectious bursal disease virus

To test whether amino acid mutations in the PBC and PHI loops of VP2 are involved in the replication and virulence of infectious bursal disease virus(IBDV), a pair of viruses, namely the moderately virulent IBDV(rG x-F9VP2) and the attenuated strain(rGt), were used. Residue mutations A222P(P_(BC)) and S330R(PHI), selected by sequence comparison, were introduced individually into r Gx-F9VP2 by using a reverse genetics system. In addition, the reverse mutation of either P222 A or R330 S was introduced into r Gt. The four modified viruses were then rescued and evaluated in vitro(CEF cells) and in vivo(SPF chickens). Results showed that A222 P elevated the replication efficiency of rG x-F9VP2 while P222 A reduced that of rG t in CEF cells. A mutation at residue 330 did not alter IBDV replication. In addition, animal experiments showed that a single mutation at either residue 222 or 330 did not significantly influence the virulence of IBDV. In conclusion, residue 222 in PBC of VP2 is involved in the replication efficiency of IBDV in vitro but does not affect its virulence in vivo, further facilitating our understanding of the gene-function of IBDV.

N-terminal domain of the RNA polymerase of very virulent infectious bursal disease virus contributes to viral replication and virulence

Dear Editor,Infectious bursal disease virus (IBDV) causes an economically significant disease of chickens worldwide (Berg,2000). The molecular basis for the virulence of very virulent IBDV (vvIBDV) is not fully understood. Previous studies have shown that genome segment A, especically VP2 protein, plays the most important role in the tropism and pathogenicity of serotype 1 IBDV (Brandt et al., 2001). VP2 is,however, unlikely to be the only factor for the virulence of vvIBDV (Boot et al., 2000). A chrono-phylogenetic study suggested that the worldwide expansion of vvIBDV

Nearly 100% exciton utilization in highly efficient red OLEDs based on dibenzothioxanthone acceptor

Improving the utilization of excitons has always been an important topic for the development of electroluminescence devices.In this work,we designed and synthesized three red TADF emitters TPA-DBT12,TPA-DBT3 and DTPA-DBT by employing dibenzothioxanthone(DBT)acceptor framework to stabilize the locally excited triplet state to participate in the reverse intersystem crossing(RISC)process.The fast RISC process and singlet radiation decay process gave rise to evidently enhanced exciton utilization.All of the red OLEDs based on these materials showed maximum EQE over 11% and high exciton utilization close to 100%.This work not only extend the acceptor framework for red materials but also provide a new perspective for the design of highly efficient red TADF materials with 100% exciton utilization by managing locally excited triplet state.

Ultra-fast and linear polarization-sensitive photodetectors based on ReSe_(2)/MoS_(2) van der Waals heterostructures

Recently,van der Waals heterostructures(vdWHs)constructed by transition-metal dichalcogenides(TMDCs)have come under the research spotlight owing to their excellent capabilities,multiple functionalities,and innovative architecture for advanced optoelectronic devices.Herein,novel heterojunction photodetectors composed of monolayer molybdenum disulfide(MoS2)and few-layer rhenium selenide(ReSe_(2))are explored for ultra-fast and polarization detection.Owing to the enhanced light-matter interactions and type-II band alignment of the ReSe_(2)/MoS_(2) heterostructure,the photodetector exhibits impressive performances at 638 nm in terms of a high on/off ratio~104,large photoresponsivity~3.52 A/W,high specific detectivity~1011 Jones,and large 3 dB frequency of 65.7 kHz.In addition,ultrafast rise/decay times(5.0/9.1 ms)are obtained under pulsed incident light contributed to the built-in electric field at the heterointerface,demonstrating a result one or two orders of magnitude faster than the currently reported values of group VII-TMDCs based photodetectors.Beyond the conventional photodetection,this photodetector also displays polarization detection capability with sensitivity 1.35.Such Re-based vdWHs provide superior platforms for the realization of ultra-fast and polarization-sensitive photodetection in broadband spectrum.