热活化延迟荧光蓝光小分子取代基效应的研究进展

近年来,作为第三代有机发光二极管(organic light-emitting diodes, OLED)发光材料的热活化延迟荧光(thermally activated delayed fluorescence, TADF)材料受到了学术界和产业界的广泛关注. TADF分子由于其单线态与三线态之间的能级差较小,三线态激子可以被环境热活化而通过反系间窜越上转换至单线态,理论上可实现100%的激子利用率,从而使得OLED器件外量子效率显著提高.TADF材料被认为是突破高效稳定有机电致蓝光发射瓶颈的潜在解决方案.一般, TADF分子为含有电子给体(donor, D)和电子受体(acceptor, A)的纯有机推拉电子体系.通过改变给体单元和受体单元的结构、数量和取代基及其位置可以有效调节TADF分子的单线态-三线态能级差、前线轨道分布、聚集态结构、电致发光颜色及其性能.同时取代基在调控给、受体单元的推拉电子能力及TADF材料的分子构型、聚集态结构和稳定性等物化特性方面扮演着非常重要的角色.本综述分别对D-A型和多重共振型TADF蓝光分子的取代基效应进行了综述,以期为高效稳定的蓝光TADF分...     

小分子给体/高分子受体型有机太阳能电池研究进展

有机太阳能电池具有低成本、柔性和质量轻等优势,是一种有应用前景的光伏技术,受到人们的广泛关注.有机太阳能电池的光敏活性层通常由p-型有机半导体(包括小分子和高分子)与n-型有机半导体(包括小分子和高分子)共混而成.小分子给体/高分子受体型有机太阳能电池具有形貌热稳定性优异的特点,值得深入研究.本综述旨在总结小分子给体/高分子受体型有机太阳能电池的研究进展,分别介绍了基于酰亚胺基、氰基和含硼氮配位键(B←N)的高分子受体的活性层材料体系的发展状况.在器件性能方面,通过分子设计、相分离形貌调控,改善了小分子给体/高分子受体的匹配性,将该类电池的能量转换效率从最初的0.29%提升至目前的9.51%,为性能的进一步提升总结了经验;在稳定性方面,基于该体系形貌热稳定性优异的特点,开发出高温耐受型有机太阳能电池器件.最后,展望了小分子给体/高分子受体型有机太阳能电池的未来发展方向和前景.     

Comparison of Intermolecular Interactions of Irreversible and Reversible Inhibitors with Bruton’s Tyrosine Kinase via Molecular Dynamics Simulations

Bruton’s tyrosine kinase (BTK) is a key protein from the TEC family and is involved in B-cell lymphoma occurrence and development. Targeting BTK is therefore an effective strategy for B-cell lymphoma treatment. Since previous studies on BTK have been limited to structure-function analyses of static protein structures, the dynamics of conformational change of BTK upon inhibitor binding remain unclear. Here, molecular dynamics simulations were conducted to investigate the molecular mechanisms of association and dissociation of a reversible (ARQ531) and irreversible (ibrutinib) small-molecule inhibitor to/from BTK. The results indicated that the BTK kinase domain was found to be locked in an inactive state through local conformational changes in the DFG motif, and P-, A-, and gatekeeper loops. The binding of the inhibitors drove the outward rotation of the C-helix, resulting in the upfolded state of Trp395 and the formation of the salt bridge of Glu445-Arg544, which maintained the inactive conformation state. Met477 and Glu475 in the hinge region were found to be the key residues for inhibitor binding. These findings can be used to evaluate the inhibitory activity of the pharmacophore and applied to the design of effective BTK inhibitors. In addition, the drug resistance to the irreversible inhibitor Ibrutinib was mainly from the strong interaction of Cys481, which was evidenced by the mutational experiment, and further confirmed by the measurement of rupture force and rupture times from steered molecular dynamics simulation. Our results provide mechanistic insights into resistance against BTK-targeting drugs and the key interaction sites for the development of high-quality BTK inhibitors. The steered dynamics simulation also offers a means to rapidly assess the binding capacity of newly designed inhibitors.     

聚合物材料表面微结构调控新策略

聚合物材料表面微结构对其功能化的实现具有至关重要的作用。在过去几十年的时间里,通过电纺、光刻、等离子处理等经典方法制备了各种各样的结构功能表面,实现在光、电、生物、化学等领域的广泛应用。然而为满足技术发展需求,实现表面微结构调控新策略的开发势不可挡。本文主要从分子扩散、材料内应力、外力的施加/释放,以及多种机制协同作用四个角度出发对聚合物表面结构调控的新策略进行介绍,并对今后聚合物表面结构调控的发展方向进行简要论述。     

H2+分子双H核对高次谐波辐射的贡献

理论研究了H2+分子双H核对高次谐波辐射的贡献。结果表明：在少周期激光场下，由于激光场的反对称性，负向H核辐射谐波强度高于正向H核。随着激光脉宽增大，激光波形趋于对称，因此导致双H核辐射谐波的反对称结构减小。谐波辐射的时频分析图显示，当激光场为正向时(E(t) > 0.0)，负向H核辐射谐波强度高于正向H核；当激光场反向时(E(t) < 0.0)，正向H核辐射谐波强度高于负向H核。最后，通过分析含时电子波包及H2+的缀饰态给出了电子在双H核之间转移的原因。     

Novel Inhibitors of Nicotinamide-N-Methyltransferase for the Treatment of Metabolic Disorders

Nicotinamide-N-methyltransferase (NNMT) is a cytosolic enzyme catalyzing the transfer of a methyl group from S-adenosyl-methionine (SAM) to nicotinamide (Nam). It is expressed in many tissues including the liver, adipose tissue, and skeletal muscle. Its expression in several cancer cell lines has been widely discussed in the literature, and recent work established a link between NNMT expression and metabolic diseases. Here we describe our approach to identify potent small molecule inhibitors of NNMT featuring different binding modes as elucidated by X-ray crystallographic studies.     

Strong Equatorial Crystal Field Enhances the Axial Anisotropy and Energy Barrier for Spin Reversal Process in Yb2 Single Molecule Magnets

The importance of equatorial crystal fields on magnetic anisotropy of ytterbium single molecule magnets (SMMs) is observed for the first time. Herein, we report three similar dinuclear ytterbium complexes with the formula [Yb₂(3-OMe-L)₂(DMF)₂(NO₃)₂]⋅DMF ( 1 ), [Yb₂(3-H-L)₂(DMF)₂(NO₃)₂]⋅DMF⋅H₂O ( 2 ), and [Yb₂(3-NO₃-L)₂(DMF)₂(NO₃)₂] ( 3 ), [where 3-X-H₂L=N′-(2-hydroxy-3-X-benzylidene)picolinohydrazide, X=OMe ( 1 ), H ( 2 ) NO₂ ( 3 )]. Detailed magnetic measurements reveal the presence of weak antiferromagnetic interactions between the Yb centers and a field-induced slow relaxation of magnetization in all complexes. A higher energy barrier for spin reversal was observed for complex 1 (U_eff=50 K) and it decreases in the order of 2 (47 K) to 3 (40 K). Notably, complex 1 shows a remarkable energy barrier within the frequency range of 1–850 Hz reported for Yb-based SMMs. Further, ab initio calculations show a higher axial anisotropy and lower quantum tunneling of magnetization (QTM) in the ground state for 1 compared to 2 and 3 . It was also observed that the presence of a strong crystal field in the equatorial plane (when the ∡ O1−Yb−O3 bond angle is close to 90°) enhances the axial anisotropy and improves the SMM behavior in the studied complexes. Both the experimental and theoretical analysis of relaxation dynamics discloses that Raman and QTM play major role on slow relaxation process for all complexes. To provide more insight into the exchange interactions, broken-symmetry DFT calculations were performed.     

La and Sr Composite Oxides-modified Graphite Felt for Aqueous Organic Redox Flow Batteries

In this study, aqueous organic redox flow batteries(AORFBs) with NaCl as supporting electrolyte were investigated. In AORFBs, the chlorine evolution reaction should be retarded, not the hydrogen evolution reaction. To enhance the catalytic activity of the graphite felt(GF) electrode, the metal oxides were proposed to decorate on the GF surface. Among the loading oxides, significant enhancement of the mass transfer and reaction activity was obtained by the presence of LaSrO_x nanoparticles. X-Ray photoelectron spectroscopy and contact angle measurements revealed that the content of oxygen-containing groups and the hydrophilicity were remarkably increased. After the electrode assembled in the battery, the LaSrO_x/GF electrode presented huge enhancement of the battery performance, obviously increasing in the battery capacity and efficiency. At a current of 50 Am/cm², the energy efficiency(EE) of the battery increased from 54.76% to 61.37% by the LaSrO_x/GF electrode. Furthermore, the cyclability of the system tested that no obviously fading was observed after 100 cycles, signifying the excellent stability of the LaSrO_x/GF electrode.     

Free Aluminylenes: An Emerging Class of Compounds

Aluminylenes (R−Al) are aluminium analogs of carbenes. In contrast to isolable carbenes, aluminylenes are extremely rare species. In the past years, pioneered by Schnöckel, Roesky and Power, a few free aluminylenes and their complexes have been reported. Such compounds have the aluminium atom in the oxidation state +I, which contrasts with classical organoaluminium derivatives that contain the element in the +III oxidation state. Aluminylenes, either in their free state or in the coordination sphere of a Lewis base, are capable of coordinating to transition metals and activating inert chemical bonds. Free aluminylenes are emerging as potent synthetic platforms for unusual aluminium species.