有机改性先驱体对含铕配合物的凝胶玻璃结构及性能的影响

分别采用γ-缩水甘油氧基三甲氧基硅烷(CH₂OCHCH₂O(CH₂)₃Si(OCH₃)₃) (GPTMS), 甲基三甲氧基硅烷(MTMS)和乙烯基三乙氧基硅烷(VTES)作为有机改性先驱体, 采用原位合成技术, 用溶胶-凝胶法制备了Eu^3＋, β-二酮噻吩甲酰三氟丙酮(TTA)及协同体1,10-菲啰啉(phen)共掺的三种有机改性二氧化硅(ormosil)玻璃. 测量了它们的发射光谱和红外光谱, 并进行了XRD, SEM和TG-DSC测试. 探讨了不同有机改性先驱体及热处理温度对原位合成的稀土有机配合物掺杂二氧化硅凝胶玻璃的发光性能、热稳定性及机械性能的影响. 结果表明, 有机改性先驱体能使凝胶玻璃结构致密, 但同时热稳定性降低; 对于荧光性能, MTMS和VTES可使其有一定的提高, 但它们的最大含量不能超过50%, 否则凝胶易失透, 而GPTMS能大幅提高凝胶的荧光性能. 通过综合比较, 选取出各种性能都较好的配方, 为今后制备较实用的具有较强荧光的含铕的凝胶玻璃提供了一定的依据.     

圆二色光谱法研究酸度、槲皮素、锌离子对β-酪蛋白二级结构的影响

采用圆二色光谱(CD)技术研究了酸度、槲皮素(Qct)和锌离子对溶液中β-酪蛋白(β-CN)二级结构的影响. 结果表明, 酸度、Qct和锌离子均能够诱导β-CN二级结构发生改变. 在pH 7.6的条件下, β-CN各种结构分别为32.6% α-螺旋, 53.5% β-折叠, 13.9% (-转角和无规卷曲; Qct使β-CN的α-螺旋含量增加、β-折叠含量减少; 锌离子和Zn-Qct配合物导致β-CN的α-螺旋含量大幅度降低, β-折叠含量略有增加, 同时转角和无规的含量也大幅度增加.     

环状烯酮与环状1-氮杂二烯的非对映及对映选择性[4+2]环加成反应

有机胺能催化环状烯酮化合物在多个位点发生不对称合成反应. 最近,我们发展了手性伯胺催化β-取代2-环戊烯酮与从糖精衍生的1-氮杂二烯的α’,γ-区域选择性的[5+3]形式环加成反应. 这里我们将报道采用β-取代2-环己烯酮或β-未取代2-环戊烯酮时,在手性伯胺催化下却与相同1-氮杂二烯发生完全不同的α’,β-区域选择性的不对称[4+2]环加成反应,生成高度官能团化的手性[2.2.2]或[2.2.1]桥环骨架结构. 重要的是利用不同类型的手性伯胺催化剂能够实现非对映选择性的反转,分别制备高立体选择性的endo-或exo-环加成产物.     

光化学条件下(β-重氮-α,α-二氟乙基)膦酸酯与羧酸的酯化反应

利用可见光促进的O-H插入反应可以在温和条件下实现羧酸与原位生成的(β-重氮-α,α-二氟乙基)膦酸酯的酯化反应, 以良好的产率得到了含有α,α-二氟甲基膦酸酯的羧酸酯类化合物. 该反应操作简单, 对于不同的官能团具有良好的适应性. 因此, 这一反应为α,α-二氟甲基膦酸酯衍生物的合成提供了一种高效的策略.     

新型双β-环糊精键合SBA-15液相手性固定相的制备及评价

由于桥联双β-环糊精的协同包结作用和独特的多重识别功能已被广泛地用作人工模拟酶,本文尝试用桥联双β-环糊精作固定相配体,开发其手性分离功能.采用3-异氰酸丙基三乙氧基硅烷偶联剂连续反应法,首先将（6-氧-对甲苯磺酰）-β-环糊精键合到有序介孔SBA-15硅胶表面,然后与（6-乙二胺-6-去氧）-β-环糊精反应,制备一种新型的乙二胺桥联双β-环糊精键合SBA-15液相色谱手性固定相（BCDSP）.采用质谱、红外光谱、元素分析、热重分析和透射电镜等进行结构表征.在极性有机溶剂模式下,评价了新固定相的基本色谱性能,并用于β-受体阻滞剂对映体的拆分.考察了流动相中有机溶剂、三乙胺、冰醋酸改性剂用量和柱温对手性分离的影响.基于优化的色谱条件,采用双β-环糊精键合固定相成功地拆分了常用的14种β-受体阻滞剂药物对映体,其中普萘洛尔的分离度可达到2.18,卡维地洛的分离度可达到2.01,分析时间一般为10～20 min,取得了较高的分离效率.为比较研究,还制备了一种单β-环糊精固定相（CDSP）,结果发现双β-环糊精键合相可拆分14种β-受体阻滞剂,而在优化的条件下单β-环糊精键合相仅能部分拆分4种β-受体阻滞剂,且前者的分离度明显优于后者.基于实验数据对双β-环糊精和单β-环糊精固定相的分离机理的异同点展开讨论.一方面包结作用和氢键作用在桥联双β-环糊精键合相的手性分离中占重要地位,与常见的单β-环糊精固定相相似;另一方面桥联双β-环糊精固定相拥有自身的特点,两个β-环糊精腔体存在协同作用,相应于它的模拟酶功能,协同作用不仅扩大了空间识别域,还提高了立体选择性,基于双腔体的包结作用和乙二胺桥键的氢键作用等增强了固定相的手性识别能力,加上有序的SBA-15能加快传质,使得BCDSP具有较好的手性色谱性能,拥有更广泛的拆分对象、更高的分离度和更短的分析时间.新固定相的制备方法简便,手性分离功能强,色谱性能稳定,且制备成本较低.这类桥联双β-环糊精键合有序介孔SBA-15新型的快速分离材料在手性药物质量监控和药代动力学研究中存在良好的应用前景.     

氨基酸酯Katritzky盐用于β,γ-不饱和酯和γ-酮酯合成的研究

β,γ-不饱和酯和γ-酮酯是重要的合成中间体, 从丰富的氨基酸衍生的Katritzky吡啶盐出发, 在可见光照射下, 合成了一系列的β,γ-不饱和酯和γ-酮酯, 该方法具有反应条件温和, 操作简单等优点, 且有良好的官能团兼容性, 所得的产物可进一步转化.     

薤中新的甾体皂苷类化学成分

从薤(Allium chinense G. Don)的乙醇提取物中分离得到6个新甾体皂苷类化合物, 通过波谱数据及理化性质分析, 鉴定其分别为5α-cholano-22,16-内酯-3-O-β-D-吡喃葡萄糖基-(1→2)-[β-D-吡喃葡萄糖基-(1→3)]-β-D-吡喃葡萄糖基(1→4)-β-D-吡喃半乳糖苷(1)、 6-酮-5α-cholano-22,16-内酯-3-O-β-D-吡喃木糖基-(1→4)-[α-L-吡喃阿拉伯糖基-(1→6)]-β-D-吡喃葡萄糖苷(2)、 (25R)-26-O-β-D-吡喃葡萄糖基-5α-呋喃甾烷-3β,26-二醇-3-O-β-D-吡喃葡萄糖基-(1→2)-[β-D-吡喃葡萄糖基-(1→3)]-β-D-吡喃葡萄糖基(1→4)-β-D-吡喃半乳糖苷(3)、 (25R)-6-酮-26-O-β-D-吡喃葡萄糖基-5α-呋喃甾烷-3β,22α,26-三醇-3-O-α-L-吡喃木糖基-(1→4)-β-D-吡喃葡萄糖苷(4)、 (25R)-6-酮-5α-呋喃甾烷-3β,22α,24β,26-四醇-3-O-β-D-吡喃木糖基-(1→4)-[α-L-吡喃阿拉伯糖基-(1→6)]-β-D-吡喃葡萄糖苷(5)和(25R)-5α-呋甾-2α,3β,22α, 26-四醇-26-O-β-D-吡喃葡萄糖苷(6). 化合物1和2的皂苷元骨架在天然产物中首次分离得到. 选用H₂O₂诱导PC12细胞神经氧化损伤模型, 初步考察了6种新的呋甾型化合物的抗氧化活性, 实验结果表明, 化合物3对由H₂O₂诱导的细胞氧化损伤有显著的保护效果.     

有机化合物的光物理研究 ⅩⅢ.β-萘甲酸十六碳酯在L-B膜中基态二聚体及激基缔合物形成的研究

制备了β-萘甲酸十六碳酯的L-B膜。分别用Y型、Z型,以及含有硬脂酸的β-萘甲酸十六碳酯与单纯硬脂酸间隔挂法,将分子膜转移至石英载片上,研究了β-萘甲酸十六碳酯分子膜吸收以及荧光光谱。并与溶液和固态中的荧光光谱作了比较。在氯仿溶液以及在固态,β-萘甲酸十六碳酯只呈现其单体的荧光。然而,在L-B膜中,除了观察到单体的荧光外,还观察到了激发态二聚体以及激基缔合物发射的荧光。通过对β-萘甲酸十六碳酯分子膜进行热和水处理后,发现L-B膜中亲水层的介质环境有所改变,从而造成亲水层中的亲水基团的某些物理和化学性质的改变。根据实验事实,提出了β-萘甲酸十六碳酯二聚体和激基缔合物在L-B膜中形成的机制。     

β-酮烯胺类手性共价有机框架的合成及在毛细管气相色谱中的应用

利用2,4,6-三羟基-1,3,5-苯三甲醛(Tfp)和(S)-2,5-双(2-甲基丁氧基)对苯二甲酸二酰肼(Mth)作为单体, 通过席夫碱反应合成了新型的β-酮烯胺类手性共价有机框架(COF)材料TfpMth COF. 采用粉末X射线衍射、 红外光谱、 热重分析及氮气吸附-脱附等手段对制备的TfpMth COF粉末进行了表征, 结果表明其具有良好的结晶度、 高的孔隙率和优异的热稳定性. 基于此, 以该COF为新型固定相采用原位生长法制备了TfpMth COF键合毛细管柱, 成功分离了一系列直链与支链的烷烃和醇类, 以及苯/环己烷、 乙苯/苯乙烯混合物. 该结果为β-酮烯胺类COF在色谱分离中的应用提供了新思路, 也为研究新型气相色谱固定相提供了参考.     

Knorr-Paal缩合反应机制的研究Ⅰ.

从Knorr-Paal缩合反应动力学研究得出:(1)速率-pH图有钟罩形曲线;(2)负活化熵大,活化能低;(3)对-取代苯甲酸催化对-乙氧苯胺与β-二酮缩合的Brönsted α值为0.25;(4)以ρ⁺=-0.881作Hammett图与速率相关比ρ^-或ρ好;(5)苯胺类分别与β-二酮或乙酰丙酮缩合,两者有很好线性的自由能关系.可见缩合机制应是简单的羰基加成和消除(脱水)过程.     

Luminescent properties of Tb3+ and Gd3+ ions doped aluminosilicate oxyfluoride glasses

Tb³⁺ and Gd³⁺ ions doped lithium–barium–aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Tb³⁺-doped lithium–barium–aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. The luminescence intensity of Tb³⁺ ion increases for those (Tb³⁺, Gd³⁺)-codoped glasses. Energy transfer process from Gd³⁺ ion to Tb³⁺ ion is indicated.     

Luminescence properties of sol-gel derived silica gels doped and undoped with RE-complexes(RE=Eu,Tb)

The luminescence properties of silica gels and silica gels doped with two rare earth complexes,Eu(TTA)3 and Tb(o-CBA)3 (TTA=thenoyltrifluocetate,o-CBA=o-chlorobenzoic acid) are reported and discussed.Pure silica gels show a blue luminescence,and the maximum excitation and emission wavelengths depend strongly on the solvents used.Both of the studied rare earth complexes exhibit the characteristic emissions of the rare earth ions in silica gels,i.e.,Eu3+5 Do→7 FJ(J=0,1,2,3,4),Tb3+5D4→7FJ(J=3,4,5,6) transitions.Compared with the pure RE-complexes powder,the silica gels doped with RE-complexes show fewer emission lines of the rare earth ions.Furthermore the rare earth ion (Tb3+) presents a longer lifetime (1346μs) in silica gel doped with Tb(o-CBA)3 than in pure Tb(o-CBA)3 powder (744μs).The reasons responsible for these results are discussed in the context.     

Photophysical Properties of Metal Ion Functionalized NaY Zeolite

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu³⁺, Tb³⁺, Ce³⁺, Y³⁺, Zn²⁺, Cd²⁺, Cu²⁺) exchanged zeolite, rare‐earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Y³⁺ and rare‐earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Zn²⁺ are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare‐earth ion broadens the application of zeolite as a luminescent host. The Eu³⁺ ion exchanged zeolite shows white light luminescence with a great application value and Ce³⁺ exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite.     

Spectroscopic studies on the interaction of cilostazole with iodine and 2,3-dichloro-5,6-dicyanobenzoquinone

Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln³⁺). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb³⁺–FQ and Eu³⁺–FQ complexes have been investigated in this contribution. Ce⁴⁺–SO₃²⁻ in acidic conditions was taken as the CL system and sensitized CL intensities of Tb³⁺–FQ and Eu³⁺–FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb³⁺–FQ complexes show characteristic peaks of Tb³⁺ at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb³⁺–ENX, Tb³⁺–NFLX, Tb³⁺–LMFX and Tb³⁺–FLRX display relatively strong emission intensity compared with Tb³⁺–OFLX, Tb³⁺–RFX, Tb³⁺–GFLX and Tb³⁺–SPFX. Quite weak peaks with unique characters of Eu³⁺ at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu³⁺–ENX, but no notable sensitized luminescence and CL of Eu³⁺ could be observed when Eu³⁺ is added into other FQ. The distinct differences on emission intensity of Tb³⁺–FQ and Eu³⁺–FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln³⁺. The different sensitized luminescence and CL signals among Tb³⁺–FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb³⁺–FQ and Eu³⁺–FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results.     

Clustering of rare earths in GeAs sulfide glass

Clustering of rare-earth dopants in GeAs sulfide glasses was studied by fluorescence spectroscopy of Pr-doped glasses and by EPR measurements of Gd-doped samples. The linewidth of the g  2 resonance of Gd³⁺, as well as the relative intensity of emission from the ¹D₂ level of Pr³⁺, was used as a relative measure of rare-earth clustering. Rare earths were found to have low solubility in uncodoped GeAs sulfide glasses, which also displayed poor fluorescence efficiency due to severe clustering. Codoping such glasses with Ga greatly enhanced rare-earth solubility and dispersal, particularly for Ga:rare earth ratios ≥ 10:1, as evidenced by the narrower EPR resonances and more intense luminescence of Gd- and Pr-doped glasses, respectively. In, P and Sn were also observed to ‘decluster’ rare earths, although less efficiently than Ga, whereas codoping with I was found to have no effect on clustering. These phenomena are explained by a structural model in which (1) rare-earth dopants and codopants are spatially associated and (2) rare-earth dispersal is accomplished by a statistical distribution of codopants in tetrahedral network sites.     

Preparation and Optical Characterization of Organoeuropium-Doped Silica Gels

Gels have been investigated as potential matrices for rare earth luminescence. The use of complexing ligands in the sol-gel synthesis of the rare-earth doped glasses has been suggested to improve the rare earth ion luminescence properties in these matrices due to the changes in the local environment experienced by the rare earth ion. In this work, transparent Eu3+-doped gels were prepared from Si(OCH3)4 and fluorinated and/or complex-forming Eu3+ precursors (Eu(fod)3, (CF3 SO3)3Eu, (CF3CO2)Eu · 3H2O, Eu(thd)3 and Eu(acac)3). Results of emission, fluorescence line narrowing and lifetimes studies of Eu3+-doped gels derived from Si(OCH3)4 and fluorinated/chelate Eu3+ precursors are presented. The results were interpreted in terms of the evolution of the Eu3+ fluorescence in systems varying from solutions to the gels densified to 800°C. Analysis of the fluorescence decays of the 5D0 state suggests that the use of the fluorinated Eu3+ precursors reduces the hydrophobic content in the silica gels matrices. FLN studies indicate that Eu3+ clustering occurred in all densified samples.     

氧化铝对稀土有机配合物掺杂溶胶凝胶玻璃结构及发光性能的影响

Both silica glass materials singly doped with rare earth organic complex and co-doped with Al^3 were prepared by in situ sol-gel method respectively. XRD and SEM measurements were performed to verify the non-crystalline structure of the glass. The excitation spectra, emission spectra and IR spectra were measured to analyze the influence of the glass contents on the structure of the glass and the energy level of the doped Eu(IH) ions. The effect of Al^3 on the photoluminescence properties of rare earth organic complex in silica glass was investigated. The IR spectra indicated that the in situ synthesized europium complex molecule was confined to the micropores of the host and the vibration of the ligands was frozen. When Al2O3 was doped into the silica host gel, the rare earth ions in the silica network were wrapped up and dispersed by Al2O3, so the distribution of Eu(Ⅲ) complex in the host was morehomogeneous, and the luminescence intensity of ^5D0-^7F2 transition emission of the Eu^3 ions was improved. The results showed that an appropriate amount of Al^3 added to the gel glass improved the emission intensity of the complex in the silica glass, and when the content of Al2O3 reached 4 mol%, the maximum emission intensity could be obtained compared with that of other samples containing different Al2O3 contents.     

ZnO-B2O3∶Tb3+长余辉玻璃的发光性质

通过还原方法制备了Tb³⁺离子掺杂的硼酸锌玻璃，并观察到在254 nm紫外光激发后有明亮的绿色长余辉发光现象，余辉时间达6 h。通过激发与发射光谱、余辉光谱、余辉衰减曲线、热释光谱、热释光释出速率衰减曲线等得到的信息，研究了Tb³⁺离子掺杂的硼酸锌玻璃的发光性质。     

Photophysical Properties of Lanthanide (Eu3+, Tb3+) Hybrid Soft Gels of Double Functional Linker of Ionic Liquid–Modified Silane

Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu³⁺, Tb³⁺) tetrakis β‐diketonate into the covalently bonded imidazolium‐based silica through electrostatic interactions. Here, the imidazolium‐based silica matrices are prepared from imidazolium‐derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu³⁺, Tb³⁺). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β‐diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies.