杯[8]芳烃及其C60络合物有序阵列的构筑

文章介绍了最近作者对杯芳烃及其C60络合物有序阵列的研究结果，以多孔的杯[8]芳烃阵列为模板，通过主客体相互作用，在Au(111)表面上成功构筑了高度有序的C60阵列，这一结果为富勒烯等功能分子有序阵列的制备、表面可控组装以及纳米信息存储器件的构筑等提供了又一可能性。     

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。     

Spectrofluorimetric study on the inclusion behavior of p-sulfonated calix arene with cetyltrimethylammonium bromide and analytical application

The characteristics of host-guest complexation between p-sulfonated calix [G. Arena, S. Gentile, F. G. Gulino, D. Sciotto, C. Sgarlata, Tetrahedron Lett. 45 (2004) 7091] arene (SC6A) and cationic surfactant cetyltrimethylammonium bromide (CTAB) were studied by fluorescence spectrometry. A 1:1 stoichiometry for the complexation was established and the complex constant was also calculated by a deduced equation. It was found the fluorescence of the complex could be remarkably quenched by an appropriate amount of ceftriaxone sodium (CTRX). Based on the results, a novel spectrofluorimetric method for determination of CTRX was developed with a linear range of 9.2×10⁻⁷-8.5×10⁻⁵ mol L⁻¹ and a detection of 3.5×10⁻⁷ mol L⁻¹. The proposed method was used to determine CTRX in their commercial preparations with satisfactory results. Moreover, the probable interaction mechanisms of the systems were also discussed.     

Electrochemical synthesis of Ag nanoparticles supported on glassy carbon electrode by means of p-isopropyl calix[6]arene matrix and its application for electrocatalytic reduction of H2O2

The silver nanoparticles were prepared on the glassy carbon (GC) electrode, modified with p-iso propyl calix[6]arene, by preconcentration of silver ions in open circuit potential and followed by electrochemical reduction of silver ions. The stepwise fabrication process of Ag nanoparticles was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared Ag nanoparticles were deposited with an average size of 70 nm and a homogeneous distribution on the surface of electrode. The observed results indicated that the presence of calixarene layer on the electrode surface can control the particle size and prevent the agglomeratione and electrochemical deposition is a promising technique for preparation of nanoparticles due to its easy-to-use procedure and low cost of implementation. Cyclic voltammetry experiments showed that Ag nanoparticles had a good catalytic ability for the reduction of hydrogen peroxide (H₂O₂). The effects of p-isopropyl calix[6]arene concentration, applied potential for reduction of Ag⁺, number of calixarene layers and pH value on the electrocatalytic ability of Ag nanoparticles were investigated. The present modified electrode exhibited a linear range from 5.0 × 10⁻⁵ to 6.5 × 10⁻³ M and a detection limit 2.7 × 10⁻⁵ M of H₂O₂ (S/N = 3) using amperometric method.     

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.     

Self‐assembly of p‐tert‐butyl thiacalix[4]arenes and metal cations into nanoscale three‐dimensional particles

The shape of supramolecular aggregates based on stereoisomers of p‐tert‐butyl thiacalix[4]arenes functionalized with secondary, tertiary amide and hydrazide groups at the lower rim in cone, partial cone and 1,3‐alternate conformations with several metal cations were investigated by atomic force microscopy. The examined p‐tert‐butyl thiacalix[4]arenes form host–guest complexes; dimers, spherics ellipsoids and elongated nanoscale particles depending on the conformation of macrocycles, the nature of the binding centers and the nature of the metal cation. Only associates formed by p‐tert‐butyl thiacalix[4]arenes with morpholide groups at the lower rim in cone conformation with silver cations exhibited a higher antimicrobial activity. Copyright © 2012 John Wiley & Sons, Ltd.     

A combined experimental and theoretical study on p‐sulfonatocalix[4]arene encapsulated 7‐methoxycoumarin

Host‐guest interactions are essential in chemistry, biology, medicine and environmental science. In this combined experimental and theoretical contribution, the encapsulation of 7‐methoxycoumarin (herniarin, 7MC) with p‐sulfonatocalix[4]arene (p‐SC4) is studied using absorption and fluorescence spectroscopy, cyclic voltammetry and computational approaches. The 1:1 stoichiometry is confirmed using Job's plot. Our results show that the keto group of 7MC is the main source for electrochemical conversion of this complex. The excited state 7MC radiative decay is studied using time‐correlated single photon counting technique. The computed UV‐Vis absorption spectra for this complex at gas phase and solvent are online with the experimental spectra. Moreover, we determined the binding energy and the binding constant of the 7MC‐p‐SC4 complex. Density functional theory computations revealed that stabilization of the complex formed by p‐SC4 and 7MC is due to weak noncovalent and dispersive types of interactions. A comparison with encapsulation of amino acids by p‐SC4 is also conducted. Finally, we show that the flexibility of p‐SC4 and the weak nature of its interaction with 7MC are on the origin of the reversibility of encapsulation, which is mandatory for applications such as drug delivery.     

Recognition of aromatic amino acids and proteins with p‐sulfonatocalix[4]arene – A luminescence and theoretical approach

The host–guest interaction of p‐sulfonatocalix[4]arene (p‐SC4) with aromatic amino acids (AAs) and two proteins has been studied using UV–Vis absorption, fluorescence, and theoretical methods. Spectral studies supported by binding constant and calculated binding energy (BE) values show that p‐SC4 binds more strongly with tyrosine compared with other AAs. The application of Bader's theory of atoms in molecule shows the involvement of various types of noncovalent interactions in the formation of the host–guest complexes. Both tyrosine and histidine have strong electrostatic interaction with the sulfonato group and other two AAs have dominant π?π interaction with the aromatic rings of calixarene. In addition, the role of C?H···O, C?H···π and lone pair···π (lp···π) interactions in the stabilization of p‐SC4‐AA complexes has also been realized from the atoms in molecule analysis. The electron density at the bond critical points varies with the calculated BEs and trend in BEs is in good agreement with the experimental binding constant values. The work has been extended to the binding of p‐SC4 with proteins, bovine serum albumin and ovalbumin. Ovalbumin exhibits stronger binding with p‐SC4 than bovine serum albumin. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of the inclusion behavior between p-sulfoniccalix[8]arene and norfloxacin by fluorescence spectroscopy

The host-guest complexation between p-sulfoniccalix[8]arene (SC₈A) and norfloxacin (NFLX) in aqueous solution was investigated by fluorescence spectroscopy. Strong fluorescence intensity of the NFLX aqueous solution alone and obvious fluorescence quenching of NFLX solution in the presence of SC₈A were observed. The fluorescence lifetimes of NFLX and SC₈A-NFLX inclusion complex were determined and the effect of temperature on SC₈A-NFLX inclusion complex was studied. The static quenching of the inclusion was obtained, that is the SC₈A can form a nonfluorescent ground-state inclusion complex with NFLX. As the results show, the combined ratio (n) was 1:1 and association constant K was 1.17×10⁵ L/mol. Based on the experimental results, the mechanism of the inclusion complex was explored. The space matching, electrostatic force and hydrogen bond play important effects in the inclusion process. Subsequently, the addition of bovine serum albumin (BSA) solution led to the recovery of fluorescence intensity. It is indicated that BSA can liberate the NFLX into the solution by destructing the SC₈A-NFLX inclusion complex. Hence SC₈A may be used for controlled-release drug delivery in the pharmaceutical industry.     

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.     

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。     

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.     

Theoretical study of one‐ and two‐photon absorption properties of expanded donor–acceptor calix[4]arenes

Two types of donor(D)–acceptor(A) calix[4]arenes have been theoretically studied using DFT//B3LYP/6‐31G(d) method and ZINDO/CISD method. The calculations show that the substitution of C? C by the conjugation bridge C?C and N?N plays an important part in altering one‐photon absorption (OPA) and two‐photon absorption (TPA) properties. The maximum OPA wavelengths of all studied compounds are less than 400 nm, which means high transparency. The geometry of the calixarenes strongly influences the TPA properties of the studied compounds. In addition, the nitro derivatives have a wider TPA response range than other non‐nitro derivatives. The tetrasubstituted calix[4]arenes (type B calixarenes) have a larger TPA cross‐section values than the bisubstituted calix[4]arenes (type A calixarenes). Copyright © 2009 John Wiley & Sons, Ltd.     

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.     

Phosphorylated amino derivatives of thiacalix[4]arene as membrane carriers: synthesis and host–guest molecular recognition of amino,hydroxy and dicarboxylic acids

Promising membrane transport and separation systems for selected dicarboxylic, α‐hydroxy‐ and α‐amino acids based on thiacalixarene platform have been developed. For the first time, p‐tert‐butyl thiacalix[4]arenes functionalized at the lower rim with aminophosphonate fragments have been obtained and characterized. As was established by UV–vis spectroscopy, membrane extraction and HPLC, the substitution of amino groups by α‐aminophosphonate units significantly enhances the selectivity of host molecules that bind to aspartic and glycolic acids. The aminophosphonate compounds synthesized can be used in the development of sensors and systems employed in the purification and separation of organic acids. Copyright © 2013 John Wiley & Sons, Ltd.     

水溶性磷酸盐柱[5]芳烃与吖啶橙的络合行为

本文首先构建了水溶性磷酸盐柱[5]芳烃（PP5A）与阳离子荧光染料吖啶橙（AO）主-客体络合物.然后通过紫外光谱（UV）、红外吸收光谱（IR）、分子荧光光谱（MFS）、一维和二维核磁共振（NMR）波谱技术（包括¹H NMR和NOESY）研究了PP5A与AO的络合行为.此外,还研究了pH及两种表面活性剂——十二烷基硫酸钠（SDS）和十六烷基三甲基溴化铵（CTAB）对AO/PP5A络合体系的荧光强度的影响.最后,采用分子对接计算了PP5A与AO和CTAB的络合模式及络合能.研究表明,AO与PP5A形成1：1的主-客体络合物;在pH=3~11范围内,PP5A均能使AO的荧光强度发生减弱或淬灭;SDS和CTAB的加入并不会对AO/PP5A络合体系的荧光强度产生显著影响.AO与PP5A络合时产生的荧光强度变化可为荧光传感器的设计提供理论基础.     

杯[8]芳烃-硝酸稀土配合物的红外光谱及荧光性能

合成了以对叔丁基杯[8]芳烃(LH₈)、硝酸根及DMF为配体,单一稀土RE³⁺(Sm³⁺、Eu³⁺、Tb³⁺、Dy³⁺)及混合稀土Tb³⁺:Ln³⁺(Ln=La³⁺,Gd³⁺,Y³⁺)为中心的7种稀土配合物,对其进行了元素分析、摩尔电导、热谱、红外光谱及荧光性能研究.荧光光谱的测试表明所有Tb³⁺及其共掺杂配合物具有较强的特征荧光发射,荧光惰性离子La³⁺、Gd³⁺、Y³⁺对Tb³⁺的荧光有增强作用,其中Y³⁺的荧光增强作用最大,Gd³⁺次之,La³⁺最小.     

A Preliminary Investigation of the Complexation of Dopamine by p‐Sulfonated Calix[4, 6] Arene and β‐Cyclodextrin Using Fluorescence Spectrometry

The inclusion complexes of p‐sulfonated calix[4, 6] arene and β‐cyclodextrin with dopamine were studied by fluorescence spectrometry in aqueous media. It was found that the fluorescence intensity of dopamine regularly decreased upon the addition of p‐sulfonated calix[4, 6] arene, on the contrary, it increased upon the addition of β‐cyclodextrin. ¹H NMR spectra were applied to verify the formation of the complexes. According to the experimental results, 1:1 stoichiometry for the complexes was established and their association constants at 25°C were calculated by applying a deduced equation. Judging from the magnitude of their inclusion constants, the p‐sulfonated calix[4, 6] arene showed better inclusion capability than β‐cyclodextrin. The probable interaction mechanisms are proposed.     

蚕丝蛋白的NMR研究Ⅲ.天蚕茧层固态13C CP-MASNMR研究

本文分别测定了东北天蚕茧和龙蛓天蚕茧各内,中,外三层茧层的固态¹³C CP-MASNMR波谱,对其谱峰进行了归属,估算了谱峰区主要谱线在该区所占的比例,还计算了各个茧层丝蛋白中无定形状态所占的百分含量。谱图显示了东北天蚕茧层与龙(蛓)天蚕茧层丝蛋白结构的差异。