荧光光谱滴定法研究对磺酸基杯[4]芳烃对吖啶的包结作用

合成了对磺酸基杯[4]芳烃(1),并用荧光光谱滴定法研究了不同温度下(1)在柠檬酸缓冲溶液(pH=5.92,0.1 mol·L-1)中对吖啶的包结行为.在一定的浓度范围内,当加入(1)后,吖啶的荧光峰有红移,且荧光强度随着所加的(1)浓度的增大而发生猝灭.结果显示二者形成了1∶1的稳定包合物.计算了在15.0,20.0,25.0及30.0℃下的包结稳定常数,它们依次为3.08×105,4.45×104,2.58×104和8.90×103,并计算了热力学参数△G,△H和△S.结果说明反应是放热的且是焓变驱动的.其包结机理可能为吖啶部分进入了对磺酸基杯[4]芳烃的空腔中,且吖啶稠环的质子化的N原子与(1)的一个SO3-基团之间以较强的静电作用成键;在此强静电作用的驱动下以及较弱的范德瓦耳斯力、疏水作用的辅助下主客体形成了1∶1的配合物.     

荧光光谱法研究儿茶素与对磺化杯[n]芳烃的相互作用

采用荧光光谱法在室温下研究了酸性(pH=2.00)、中性(pH=7.00)及碱性(pH=9.00)条件下对磺酸基杯[4]芳烃(SCX4)、对磺酸基杯[6]芳烃(SCX6)及对磺酸基杯[8]芳烃(SCX8)与儿茶素的包合作用.固定儿茶素浓度,逐渐改变对磺化杯[n]芳烃的浓度,儿茶素的荧光强度有规律地降低,表明主-客体包合物的形成.同时用最小二乘法进行非线性拟合计算出包合常数,初步验证了对磺化杯[n]芳烃与儿茶素1:1的包合模式,并且室温条件下,SCX8在pH=9.00的磷酸缓冲体系中对儿茶素的包合能力最强,包合常数为2.769×104L·mol-1.     

荧光法研究对羧基苯偶氮基杯[8]芳烃与诺氟沙星的作用

合成了一种超分子探针对羧基苯偶氮基杯[8]芳烃(简称CPAC).利用荧光光谱法研究了溶液状态下该探针与诺氟沙星(简称NFLX)的相互作用.实验表明,两者之间存在较强烈的相互作用,CPAC与NFLX形成外式包结物,静态猝灭NFLX的荧光,CPAC的杯腔体与NFLX的喹啉环间的疏水作用是主要作用方式.测定了该反应的结合常数(K=6.38×105 L·mol-1)和结合比(n=1).实验发现,小牛胸腺DNA能夺取CPAC-NFLX体系中的CPAC,使NFLX游离,说明超分子化合物CPAC可用于诺氟沙星药物的储存和定点释控.     

稀土金属离子与色氨酸相互作用的荧光光谱研究

在碱性介质中,稀土离子与色氨酸形成离子缔合型异配位络合物使色氨酸的荧光猝灭,在pH=10-11的H3BO4－HAc-H3PO4-NaOH介质中,色氨酸的荧光发射和稀土离子对其荧光猝灭均达到最大值,各个稀土离子对色氨酸的荧光猝灭强度也基本相似,本文还建立了稀土离子与色氨酸配合物的分子模型并对其荧光猝灭机理进行了探讨。     

荧光光谱法研究对-二甲氨甲基-杯[8]芳烃与DNA相互作用

首次采用阿霉素作荧光探针研究了水溶性对-二甲氨甲基-杯[8]芳烃(简称杯[8]胺或CX8)与小牛胸腺DNA相互作用,并考察了溶液的pH值、离子强度及解链DNA对DNA和杯[8]胺相互作用的影响。实验发现,DNA能猝灭阿霉素的荧光,向该体系中加入杯[8]胺时荧光又逐渐增强,这说明杯[8]胺能与DNA的磷氧负离子强烈作用。通过Scatchard图等进一步分析发现,杯[8]胺对DNA-阿霉素的影响表现为混合模式,一方面,在中性或酸性的条件下,杯[8]胺能中和DNA上的磷氧负离子,导致DNA收缩,从而影响DNA的构象,使嵌入的阿霉素从DNA中部分游离出来,荧光增强;另一方面,杯[8]胺与阿霉素也存在静电位点竞争。     

杯[4]芳烃纳米粒子的制备及其光谱性质研究

用再沉淀法制备了一种新型的有机纳米微粒子—杯[4]芳烃纳米粒子(CN),通过透射电镜观察其平均尺寸约为40 nm, 与杯[4]芳烃分子相比具有较好的荧光性能。在弱酸性条件下,适量的Fe3+能使其荧光发生明显猝灭,荧光猝灭值与Fe3+的浓度在一定范围内呈良好线性关系,据此建立了一种测定Fe3+的荧光新方法。在最优化条件下,测得Fe3+的线性范围和检出限分别为1.0×10-6～2.4×10-5 mol·L-1和3.1×10-7 mol·L-1。将其应用于水样中三价铁离子的定量分析,回收率和相对标准偏差都令人满意。     

铽-甲苯磺酸妥舒沙星稀土敏化荧光与应用

在pH=5.00的HAc-NaAc介质中,铽(Ⅲ)与甲苯磺酸妥舒沙星发生络合,产生稀土敏化荧光现象,使铽(Ⅲ)的λem=545nm处荧光增强最为显著,当适量叶酸加入时,铽(Ⅲ)的荧光强度明显下降,以此建立了简单、快速、灵敏的测定叶酸的荧光分析方法。叶酸溶液在7.3×10-5—5.6×10-8mol/L浓度范围内符合线性关系,方法检出限为8.1×10-9mol/L。该法用于叶酸片剂中叶酸含量的测定,其回收率为98.4%—102.9%。     

血卟啉衍生物与血红蛋白相互作用的光谱特性研究

采用荧光光谱法和紫外-可见吸收光谱法研究了在不同温度下,血卟啉衍生物(HPD)与血红蛋白(Hb)结合反应的荧光猝灭光谱行为。证实由于非辐射能量转换机制,HPD对Hb有较强的荧光猝灭能力。根据Stern-Volmer方程和Lineweaver-Burk双倒数函数曲线,计算其结合常数在高温时要比低温时大,并获得相关结合常量和热力学参数。根据Fster能量传递原理计算出临界结合位点R₀＝3.22 nm。     

喜树碱与DNA相互作用的光谱学研究

采用光谱法研究了抗癌药物喜树碱与DNA的相互作用。DNA引起喜树碱的吸收光谱轻微的红移和减色并导致喜树碱的荧光猝灭,说明喜树碱和DNA形成基态复合物。通过计算确定了二者的结合常数,结合位点数及主要结合力。同时考察了离子强度、磷酸根浓度、猝灭剂KI对二者相互作用的影响并比较了单、双链DNA和喜树碱相互作用的程度。变性实验确定了喜树碱-DNA复合物的熔点为60 ℃, 比纯DNA的熔点低18 ℃。实验结果表明喜树碱和DNA之间主要是沟槽作用模式。     

荧光猝灭法研究苯乙烯氧化物与DNA的相互作用

荧光猝灭法是一种可以研究苯化合物与ＤＮＡ相互作用的动态过程的方法。研究结果表明，苯乙烯氧化物与ＤＮＡ的相互作用与苯乙烯氧化物浓度的关系服从动力学一级方程。     

荧光法研究对-二甲氨甲基-杯[8]芳烃与二苯胺磺酸钠包结作用

用荧光法研究了水溶性对-二甲氨甲基-杯[8]芳烃与二苯胺磺酸钠的相互作用。发现当对-二甲氨甲基-杯[8]芳烃加入到二苯胺磺酸钠溶液时,二苯胺磺酸钠的荧光峰发生了明显的蓝移,荧光增强,可能的作用机理是二苯胺磺酸钠中的磺酸根与对-二甲氨甲基-杯[8]芳烃中带正电的氮原子之间有较强的静电作用,二苯胺磺酸钠进入了对-二甲氨甲基-杯[8]芳烃的疏水空腔。同时研究了几种有机溶剂对包结物的荧光强度的影响,初步探讨了其作用机理。     

光谱法结合分子模拟技术研究左氧氟沙星与胃蛋白酶的相互作用机理

在模拟生理条件下,采用荧光光谱法结合分子对接技术研究了左氧氟沙星与胃蛋白酶的相互作用。不同温度下的Stern-Volmer曲线结果表明,左氧氟沙星主要以静态猝灭的方式使胃蛋白酶的荧光产生猝灭。由热力学数据确定了两者之间存在的作用力主要为静电作用力。三维荧光光谱实验结果表明,在左氧氟沙星与胃蛋白酶发生作用过程中引起了胃蛋白酶中酪氨酸和色氨酸残基构象的变化,从而导致胃蛋白酶发生了猝灭作用。为了进一步探讨左氧氟沙星与胃蛋白酶相互作用的分子机理,利用分子对接技术对两者的相互作用进行模拟。结果表明两者发生作用的区域位于胃蛋白酶的催化活性中心,左氧氟沙星的进入导致酶催化中心氨基酸残基的微环境发生改变,从而对胃蛋白酶的活性造成影响,这可能也是左氧氟沙星引起消化不良的主要原因。     

Photophysics of Calix[4]biscrown-Based Ditopic Receptors of Caesium Containing One or Two Dioxocoumarin Fluorophores

The ditopic receptors Calix-COU1 and Calix-COU2 consist of a calix[4]biscrown containing one or two dioxycoumarin fluorophores, respectively, inserted into the crown. They can form 1:1 and 2:1 (metal:ligand) complexes with caesium ions. The photophysical properties of the 1:1 complexes can be explained by (i) cation tunneling through the tube-shaped cavity (composed of the four phenyl rings) of the calix[4]biscrown, (ii) photodisruption of the interaction between the bound cation and the oxygen atoms belonging to both the coumarin moiety and the crown, (iii) photoinduced motions of the cation.     

计算机模拟和光谱法研究头孢他美酯与胃蛋白酶的结合机理

采用多种光谱法及计算机模拟技术研究了298,303,310 K温度下,头孢他美酯（CFP）与胃蛋白酶（PEP）之间的结合机理。结果表明,CFP主要以非辐射能量转移的静态猝灭方式猝灭PEP的荧光,两者主要通过静电作用力结合,其结合率在310 K为74.73%~92.13%。采用同步荧光法和圆二色谱法研究CFP对PEP的反应,结果表明两者的结合诱导了PEP的构象变化,使PEP的内源荧光猝灭。采用计算机模拟CFP与PEP的对接,结果表明CFP结合在PEP的催化活性位点处,该结论与光谱法所得结果一致。利用CFP对PEP的荧光猝灭反应,可以实现对实际药品中CFP含量的快速测定。     

Quenching of Pyrene Fluorescence by Calix[4]arene and Calix[4]resorcinarenes

Interactions involving calixarene and its derivatives are of major importance due to their widespread applications as unique hosts. Fluorescence from a common probe pyrene is used to study interactions involving calix[4]resorcinarene [1a] and its tetra-morpholine derivative [1b] in 1 M aqueous NaOH. These compounds efficiently quench the pyrene fluorescence. A comparison with the fluorescence quenching behavior of N-methylmorpholine clearly indicates the presence of long-range interactions involving 1a and 1b; the interactions are specific to the calixarene molecular framework. This is not the case for a tetra-nitro-substituted calix[4]arene [2b], an electron/charge acceptor quencher, as p-nitrophenol also shows similar interactions with pyrene. Effectiveness of cesium as the quencher of pyrene fluorescence is reduced in the presence of electron/charge donating 1b; fluorescence enhancement is observed upon addition of cesium as the concentration of 1b is increased in the solution. The role of calixarene framework in interactions involving such compounds is established.     

Spectroscopic Study of the Photophysical Properties of Rare Earth Ions Encapsulated: Water Soluble Functional Calixresorcin[4]Arene

Abstract

A novel macrocyclic compound-water soluble functional calixresorcin[4]arenes—tetra para sulfo-phenylmethyl-calixresorcin[4]arenes was synthesized for the first time. the photophysical properties of terbium and europium ions encapsulated in the macrocyclic ligand were studied in detail. the triplet state energy of the calixresorcin[4]arene was determined to be 24400 cm^?1 by the low temperature phosphorescence spectrum and it was found that it can sensitize both terbium ion and europium ion. the possible energy transfer process between the functional calixresorcin[4]arene and the encapsulated Tb³⁺ and Eu³⁺ was discussed. the luminescence quantum efficiency of Tb³⁺- calixresorcin[4]arene was calculated.     

Infrared Luminescence of Ytterbium Ion in Complexes with Calix[4]resorcinarenes

New ytterbium complexes with seven calix[4]resorcinarenes containing methoxycarbonyl, methyldiethylamino groups, and bromine as the substituents in the resorcinol ring and methyl or phenyl substituents in the macro ring were synthesized. The absorption, excitation, phosphorescence, and luminescence spectra of these complexes were studied. The positions of triplet levels of the ligands were measured and the values of relative quantum yields for the complexes were calculated. The paths of ligand–lanthanide energy transfer are discussed.     

Spectroscopic Studies on the Interaction Between Aucubin and Bovine Serum Albumin Without or With Copper II or Iron III

The binding of aucubin to bovine serum albumin in the absence or presence of copper II or iron III has been studied by fluorescence, UV-Vis absorbance, synchronous fluorescence, and circular dichroism spectroscopies at pH 7.40. The results of fluorescence showed that the static quenching mechanism played a major role without or with copper II or iron III, and the quenching constant, binding constant, and binding site number decreased with copper II or iron III at three different temperatures (310 K, 300 K, and 290 K). This indicated that the drug would take effect more promptly in the presence of metal ions than in the absence of them. Thermodynamic parameters revealed that hydrophobic forces played vital roles and the binding process was spontaneous without or with copper II or iron III. The results of synchronous fluorescence showed that the polarity of the microenvironment around tryptophan and tyrosine residues changed insignificantly without or with copper II or iron III. The results of circular dichroism showed that there were slight reductions in the α-helix content of bovine serum albumin. In conclusion, copper II or iron III could reduce the binding ability between aucubin and bovine serum albumin, resulting in enhanced maximum effects of aucubin. The relative knowledge would contribute to the pharmaceutical development and clinical application of aucubin.

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