Bimodal Fluorescence/Magnetic Resonance Molecular Probes with Extended Spin Lifetimes

Bimodal molecular probes combining nuclear magnetic resonance (NMR) and fluorescence have been widely studied in basic science, as well as clinical research. The investigation of spin phenomena holds promise to broaden the scope of available probes allowing deeper insights into physiological processes. Herein, a class of molecules with a bimodal character with respect to fluorescence and nuclear spin singlet states is introduced. Singlet states are NMR silent but can be probed indirectly. Symmetric, perdeuterated molecules, in which the singlet states can be populated by vanishingly small electron-mediated couplings (below 1 Hz) are reported. The lifetimes of these states are an order of magnitude longer than the longitudinal relaxation times and up to four minutes at 7 T. Moreover, these molecules show either aggregation induced emission (AIE) or aggregation caused quenching (ACQ) with respect to their fluorescence. In the latter case, the existence of excited dimers, which are proposed to use in a switchable manner in combination with the quenching of nuclear spin singlet states, is observed     

Allenyl esters as quenching agents for ruthenium olefin metathesis catalysts

In the attempt to synthesize substituted allenyl esters through a metathesis coupling of unsubstituted allenyl esters and alkenes using a variety of ruthenium catalysts, it was discovered that allenyl esters themselves cleanly arrested the activity of the catalysts. Further studies suggests possible utility of allene esters as general quenching agents for metathesis reactions. To explore this idea, several representative olefin metathesis reactions, including ring closing, were successfully terminated by the addition of simple allenyl esters for more convenient purification.     

Development of 1,3a,6a-triazapentalene-labeled enterobactin as a fluorescence quenching sensor of iron ion

1,3a,6a-Triazapentalene (TAP)-labeled enterobactin was developed as an iron ion sensor. 3-Acetylated-TAP was successfully introduced to the catechol ring of enterobactin, a well-recognized siderophore secreted by various Gram-negative bacteria. The fluorescence of TAP-labeled enterobactin decreased gradually as the amount of Fe³⁺ ion as an additive was increased, and 1.2 equiv of Fe³⁺ ion completely quenched the fluorescence. In clear contrast, when other metal ions were used, the fluorescence of TAP-labeled enterobactin remained even at 5.0 equiv.     

m-6-m型Gemini双季铵盐表面活性剂与DNA的相互作用

合成了5种m-6-m型Gemini双季铵盐表面活性剂,在对产物结构和表面活性进行分析的基础上,分别采用紫外分光光度法和荧光分光光度法考察了m-6-m型Gemini双季铵盐表面活性剂与DNA的相互作用.结果表明,m-6-m型Gemini表面活性剂的CMC随烷基疏水链的增长呈逐渐下降趋势.几种表面活性剂均没有使DNA的紫外吸收峰发生红移或蓝移现象,说明复合物无嵌插作用或氢键形成,表面活性剂与DNA作用后的吸光度随表面活性剂浓度的增大而增强,当表面活性剂的浓度相同时,吸光度随疏水链的增大而逐渐减弱.Gemini表面活性剂浓度增大导致荧光强度降低,表面活性剂与DNA作用时的猝灭为静态猝灭,随着疏水链长度的增长,荧光猝灭常数降低,表面活性剂与DNA之间的作用力减弱.     

以不同铕配合物为探针分子的温敏漆制备及性能

以氧化铕(Eu_2O_3)、甲基丙烯酸(MAA)、水杨酸(HSal)、肉桂酸(HCA)和菲咯啉(Phen)为原料制备了Eu(MAA)3Phen、Eu(Sal)_3Phen和Eu(CA)_3Phen探针分子,并将不同探针分子分别加到甲基丙烯酸甲酯(MMA)中,在过氧化苯甲酰(BPO)引发下聚合,制得一系列温敏漆样品。采用红外光谱仪、荧光光谱仪和扫描电子显微镜对探针分子的结构、发光性能、形貌和温敏漆的温度猝灭性能进行了表征,研究了不同配体对探针分子发光性能和温敏漆温度猝灭性能的影响。结果表明,探针分子Eu(MAA)3Phen的荧光强度明显高于Eu(Sal)_3Phen和Eu(CA)_3Phen,相应的3种温敏漆Eu(MAA)3Phen/PMMA、Eu(CA)_3Phen/PMMA和Eu(Sal)_3Phen/PMMA均有良好的温度猝灭特性,但是对比发现在55~65℃范围内Eu(MAA)3Phen/PMMA和Eu(CA)_3Phen/PMMA温敏漆的灵敏度较高,而在35~45℃范围内Eu(Sal)_3Phen/PMMA温敏漆的灵敏度较高,可见不同的温敏漆适用于不同的温度范围。     

Effects of the formation time of parton shower on jet quenching in heavy-ion collisions

Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma (QGP). As a multi-particle system, jets require time to develop from a highly virtual parton to a group of partons close to mass shells. In this study, we present a systematical analysis on the effects of this formation time on jet quenching in relativistic nuclear collisions. Jets from initial hard scatterings were simulated with Pythia, and their interactions with QGP were described using a Linear Boltzmann Transport (LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium. Three different estimations of the jet formation time were implemented and compared, including instantaneous formation, formation from single splitting, and formation from sequential splittings, before which no jet-medium interaction was assumed. We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets but also its dependence on the jet transverse momentum.     

基于[LnMo12]二十面体的三维稀土钼酸盐骨架的合成、结构及荧光性能

通过缓慢蒸发溶剂法合成了2例新的三维稀土钼酸盐：[Ln (H₂O)₃]₃[LnMo₁₂O₄₂]·xH₂O,其中Ln=Eu (1)、Tb (2),x=7(1),10.17(2)。这2种稀土钼酸盐中都含有新颖的二十面体[LnMo₁₂O₄₂]构建单元,该单元通过与{LnO₉}多面体进一步连接形成三维网络。光致发光测试表明,化合物1和2显示出明显不同的发射特征,这与Eu³⁺和Tb³⁺离子的不同能级跃迁密切相关。化合物1表现出较强的红色发射(CIE色度坐标为(0.66,0.33))、高发光强度、较大的荧光量子产率(约60%),对应于从⁵D0到⁷F_J (J=4、3、2、1、0)的跃迁;化合物2表现出浅绿色发射(CIE色度坐标为(0.34,0.60)),对应从⁵D₄到⁷F_J (J=6、5、4、3)的能级跃迁,其发光强度较弱和荧光量子产率较低(约20%)。有趣的是,一定量的Tb³⁺引入和大量溶剂分子的存在导致化合物2发生部分荧光猝灭,但对化合物1的荧光几乎没有影响。     

Photophysics of Silicon Phthalocyanines in Aqueous Media

Phthalocyanines have been used as photodynamic therapy (PDT) agents because of their uniquely favorable optical properties and high photostability. They have been shown to be highly successful for the treatment of cancer through efficient singlet‐oxygen (¹O₂) production. However, due to their hydrophobic properties, the considerations of solubility and cellular location have made understanding their photophysics in vitro and in vivo difficult. Indeed, many quantitative assessments of PDT reagents are undertaken in purely organic solvents, presenting challenges for interpreting observations during practical application in vivo. With steady‐state and time‐resolved laser spectroscopy, we show that for axial ligated silicon phthalocyanines in aqueous media, both the water:lipophile ratio and the pH have drastic effects on their photophysics, and ultimately dictate their functionality as PDT drugs. We suggest that considering the presented photophysics for PDT drugs in aqueous solutions leads to guidelines for a next generation of even more potent PDT agents.     

Dy3+含量对Eu2+,Dy3+共掺高硅氧发光玻璃发光性能的影响

通过控制Dy3+的掺杂浓度,制备出了不同浓度的Eu2+,Dy3+单掺和共掺高硅氧发光玻璃,测试其激发和发射光谱,讨论了Dy3+浓度对Eu2+,Dy3+共掺样品发光性质的影响。结果表明,Eu2+,Dy3+共掺高硅氧发光玻璃中存在Dy3+向Eu2+的无辐射能量传递现象,且Dy3+的引入会使高硅氧发光玻璃中Eu—O的共价作用减弱,造成Eu2+发射峰蓝移;随着Dy3+浓度的增加,Dy3+→Eu2+能量传递增强,Eu2+发光增强;Dy3+含量继续增加,则Dy3+发光出现浓度猝灭,且Dy3+→Eu2+能量传递减弱。     

荧光光谱法研究钙试剂羧酸钠与牛血清白蛋白结合反应特征

不同温度下,研究了钙试剂羧酸钠与牛血清白蛋白作用的荧光猝灭光谱、同步荧光光谱、三维荧光光谱和紫外可见吸收光谱特征;分别用SternVolmer方程和LineweaverBurk双倒数方程等处理实验数据,得到了26℃时反应的结合常数为7.664×104mol/L,结合位点数为1.522,结合反应的标准焓变、标准熵变和标准吉布斯自由能变分别为-58.36kJ/mol,-101.7J/K和-27.958kJ/mol;分析所得光谱,证实了在实验浓度和温度范围内,CCS与BSA反应可形成具有一定结构的复合物,获得了CCS对BSA构型的影响等重要信息。