Predicting lepton flavor mixing from Δ(48) and generalized C P symmetries

We propose to understand the mixing angles and C P-violating phases from the ?(48) family symmetry combined with the generalized C P symmetry. A model-independent analysis is performed by scanning all the possible symmetry breaking chains. We find a new mixing pattern with only one free parameter, excellent agreement with the observed mixing angles can be achieved and all the C P-violating phases are predicted to take nontrivial values. This mixing pattern is testable in the near future neutrino oscillation and neutrinoless double-beta decay experiments.Finally, a flavor model is constructed to realize this mixing pattern.     

高中化学项目教学案例——探寻柠檬水中的维生素C

选取“维生素C”这一生活中常见的还原性物质,面向已经学习“氧化还原反应”基础知识的高一年级学生开展项目教学活动。通过提出项目问题、师生共同拆解项目问题设计研究方案和子任务、学生实施子任务研究等项目教学环节,在形成相应子任务成果的同时,进一步帮助学生巩固从氧化性和还原性视角认识化学物质性质的认识角度,建立基于物质性质定量分析目标物质含量的实验思路和思维框架,提升学生对于氧化还原反应功能和价值的认识。     

Geometric and Electronic Behavior of C60 on PTCDA Hydrogen Bonded Network

Self-assembled supramolecular networks are promising spacer layer for electronic decoupling from the metal substrate.However,the mechanism behind of how the intrinsic electronic structure of spacer layers affects the adsorbate is still unclear.Here a hydrogen bonded network composed of n-type semiconducting molecules 3,4,9,10-perylene-tetracarboxylic-dianhydride(PTCDA)is prepared under ultra-high vacuum to serve as a spacer layer for functional organics C60 on Au(111).The geometric and electronic information of C60 was investigated by scanning tunneling microscopy and scanning tunneling spectroscopy(STM/STS)at 5 K.Effective decoupling from the metal surface yields an energy gap of 3.67 eV for C602nd,merely considering the HOMO-LUMO peak separation.The broadening of resonance peaks in STS measurements however indicates unneglected interlayer interactions in this hetero-organic system.Moreover,we scrutinize the nucleation sites of C60 on PTCDA layer and attribute this to the decreased diffusion capability on a less dense molecular arrangement possessing inhomogeneous spatial distribution of unoccupied molecular orbitals.     

Predictable site-selective radical fluorination of tertiary ethers

In this communication,we disclose the first example of metal-free and site-selective radical fluorination of readily available tertiary alkyl ethers,enabled by synergistic photocatalysis and organocatalysis.This catalytic combination allows for exclusive fluorination of tertiary C–O bonds under mild conditions even in the presence of competing reaction sites.The excellent functional group tolerance affords valuable access to sterically hindered alkyl fluorides through late-stage modification of complex molecules.The successful use of tertiary alkyl ethers in radical fluorination enhances the structural diversity of aliphatic fluorides that can be derived from naturally abundant alcohols.     

Transformations of N-arylpropiolamides to indoline-2,3-diones and acids via C≡C triple bond oxidative cleavage and C(sp^2)–H functionalization

A new palladium-catalyzed oxidative conversion of N-arylpropiolamides and H2O to various indoline-2,3-diones and acids through the C≡C triple bond cleavage and C(sp2)–H functionalization is described,which is promoted by a cooperative action of catalytic CuBr2,2,2,6,6-tetramethyl-1-piperidinyloxy(TEMPO)and O2.The method provides a practical tool for transformations of alkynes by means of a C–H functionalization strategy,which enables the formation of one C–C bond and multiple C–O bonds in a single reaction with high substrates compatibility and excellent functional group tolerance.     

碳化终温对β-Mo2C催化喹啉加氢脱氮性能影响

以MoO_3为前驱物,CH_4/H_2为碳源,采用程序升温直接还原碳化法制备不同碳化终温(640、660、680、700和720℃)的碳化钼催化剂,通过XRD、N_2吸附-脱附、SEM、TEM、XPS和Raman表征研究碳化钼的物理性质和结构性质,并研究不同碳化终温碳化钼对喹啉加氢脱氮的催化性能。结果表明,不同碳化终温的碳化钼催化剂均为β-Mo_2C,碳化终温可显著改变碳化钼表面物种含量、平均孔径和介孔分布。碳化终温为680℃时,催化剂碳化程度较高,表面氧物种含量最低,表面C/Mo物质的量比最高,对应的催化活性也最佳,在340℃、4 MPa条件下,喹啉的转化率和脱氮率均高达99%以上,芳香族类化合物的选择性可达37.8%,显示出较低的芳环破坏性。表面组成尤其是表面氧对于β-Mo_2C上喹啉加氢脱氮反应途径的调控至关重要。     

钴催化双齿导向基辅助的1-萘胺衍生物与醇的区域选择性碳氢键烷氧基化反应

研究了吡啶酰胺双齿导向的钴催化1-萘胺衍生物的区域选择性碳氢键烷氧基化反应.研究发现不仅一元醇可以作为烷氧化剂在标准条件下较好地实现1-萘胺C(8)位的烷氧化反应,而且具有多重用途的脂肪二元醇以及低聚乙二醇,也可以以中等的收率得到相应的目标化合物,这可能是钴催化碳氢键活化构筑碳氧键的首次发现.此外,利用这个实验方法,以氘代甲醇为烷氧化试剂实现了同位素标记的8-烷氧基取代的1-萘胺衍生物的合成.通过控制实验,发现该反应中吡啶酰基是最佳的双导向基团,而且反应过程可能经历了单电子转移机理.     

无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键研究进展

C—N键广泛存在于药物分子、天然产物及功能材料中,开发简洁高效的C—N键构建方法具有重要意义.近年来,无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键取得了诸多进展.该方法反应条件相对温和,反应活性较高,为C—N键构建提供了一条新途径.根据氮源类型的不同,对近年来C(sp^2)—H键的自由基反应构建C—N键的研究进展进行简要论述.     

C.I.颜料红177中间体的制备工艺改进

本文较为系统地研究了铜粉催化剂加入方式对C.I.颜料红177中间体4,4'-二氨基-1,1'-二蒽醌-3,3'-二磺酸(DAS)合成过程中的乌尔曼偶联反应速率的影响规律。 研究结果表明,在55 ℃较佳反应温度下,先加入与溴氨酸钠质量比为2:5的铜粉,反应一段时间后再加入与溴氨酸钠的质量比为1:5的铜粉,与一次性加入与溴氨酸钠的质量比为3:5的铜粉相比较,综合反应时间可节省2~3 h。 另外,对于DAS中混有的铜盐,采取在制备过程中加入柠檬酸的方法予以去除,此举可提高DAS的纯度。 当铜粉与柠檬酸的质量比为6:1时,可使DAS中铜盐的含量小于0.001%。 此外还探究了蒸馏后滤液的剩余量对DAS收率的影响,结果表明,滤液的剩余量在20 mL时,DAS的收率在95%以上。 基于本文的研究结果提出,欲进一步提高该反应的收率,需要寻找更高效的催化剂。     

基于吡咯并吡咯二酮核心的苝二酰亚胺类受体分子的合成及光伏性能

苝二酰亚胺类小分子由于其固有的强分子聚集特性,导致活性层形貌难于调控,器件效率相对于近年来报道的受体-给体-受体型稠环小分子受体一直处于劣势.针对这一关键问题,我们设计并合成了三个以吡咯并吡咯二酮为中心核的双臂型和四臂型苝二酰亚胺类小分子受体.其中,c-PDI2和nc-PDI2两个双臂型分子分别将两个苝二酰亚胺臂置于吡咯并吡咯二酮核心骨架的碳取代位和氮取代位;四臂型PDI4是将四个苝二酰亚胺臂置于吡咯并吡咯二酮核心骨架的四个取代位.通过对三个受体小分子的光谱吸收、能级水平、薄膜形貌以及光伏性能的详细研究,发现三个受体小分子都拥有扭曲的分子结构并由此带来无定形薄膜形貌,表明其分子聚集趋势得到了有效的抑制.相对于双臂型受体分子,四臂型PDI4具有更强的光吸收能力和电子传输性能,从而获得了8.45%的最高光电转换效率,是c-PDI2器件效率的2倍和nc-PDI2器件效率的1.5倍.