羟基葫芦[6]脲与孟加拉红包结作用的荧光光谱研究

采用荧光光谱法研究了羟基葫芦[6]脲(HOCB[6])对孟加拉红(TSS)的包结作用,考察了HOCB[6]浓度、缓冲液pH、温度、包结时间、有机溶剂等因素对包结作用的影响,结果表明,体系的荧光强度随着HOCB[6]浓度的升高而增强,呈现显著荧光增敏现象,同时荧光峰位有一定蓝移,Hildebrand-Benesi法计算结果显示HOCB[6]与TSS形成了1∶1的包结配合物,包结反应的热力学参数表明该包结过程为自发放热过程,这可能是主客体分子之间的疏水作用与离子偶极作用所引起的。     

葫芦[n]脲超分子水凝胶的研究进展

超分子化学的发展一直是众多研究者所关注的一大热点,葫芦[n]脲作为第四代大环主体分子,拓宽了超分子化学领域的发展.水凝胶是一种具有可拉伸性、生物相容性、环境响应性等多种优异性能的软材料.人们充分利用葫芦[n]脲优异的分子识别能力和配位能力,研究出了一系列具有特殊功能的超分子水凝胶材料.本文在结合葫芦[n]脲特点的基础上...     

基于葫芦[8]脲主-客体作用的温度及pH敏感壳聚糖超分子凝胶制备与性能

壳聚糖侧链改性合成N-(4-二甲氨基苯甲基)壳聚糖(MBCS), 通过葫芦[8]脲(Q[8])与MBCS侧链之间的主客体作用制得Q[8]/MBCS超分子凝胶. 利用红外光谱、紫外光谱、¹H NMR、X-射线粉末衍射(XRD)、热重分析(TG)和差示扫描量热(DSC)等技术对改性壳聚糖及凝胶进行表征. 以5-氟尿嘧啶(5-Fu)为模型药物, 研究载药凝胶在不同pH环境下的释药行为. 结果表明Q[8]/MBCS体系在酸性条件下, 可组装形成超分子凝胶, 该凝胶体系具有温敏性和pH敏感性. 扫描电镜(SEM)图显示凝胶具有网状交联结构, ¹H NMR谱显示, 在酸性条件下, Q[8]与MBCS含氮侧链基团间发生主客体包合作用是超分子凝胶形成的主要原因. Q[8]/MBCS载药凝胶在酸性介质中对药物具有明显的缓释作用.     

葫芦脲[7]的包结作用对亚甲基蓝和吖啶橙吸收光谱的影响

利用密度泛函方法对吖啶橙和亚甲基蓝与主体葫芦脲[7]分子作用的内、外包结物结构进行了理论计算.亚甲基蓝与葫芦脲[7]的内包结构型最稳定,吖啶橙与葫芦脲[7]的内、外包结构型的热稳定性相当.在相同的理论水平上利用时间相关的密度泛函方法计算了客体分子及其各构型包结物的激发态性质预测相应的吸收光谱.比较了客体分子的跃迁轨道组成及其性质的变化,预测葫芦脲[7]的包结作用对吖啶橙和亚甲基蓝分子的轨道能级和电子跃迁性质使其吸收光谱性质的影响.     

新型准轮烷的合成及性质研究——丁烷基紫精与葫芦[6]脲的超分子自组装

通过葫芦[6]脲(CB[6])与丁烷基紫精(BV)在水溶液中于室温下进行超分子自组装, 得到一种新型的准轮烷(BVCB), 并通过¹H NMR, IR, 质谱, 元素分析对其结构进行了表征, 证实CB[6]位于BV的脂肪链上通过非共价键与BV结合, 并且 CB[6]与BV的结合摩尔比为2∶1; 通过热重分析(TGA)、紫外-可见吸收(UV-vis)和化学还原等方法对其性质进行了研究, 证实了BVCB比BV有更高的热稳定性、UV-vis吸收和更强的氧化能力; 盐效应表明 NaI是BVCB优良的沉淀剂; 环境扫描电镜(ESEM)证实BVCB比BV具有较强的刚性和较差的结晶能力.     

荧光光谱法研究葫芦[7]脲与6-巯嘌呤和腺嘌呤的包结作用

采用荧光光谱法分别研究了葫芦[7]脲(CB[7])对6-巯嘌呤(6-MP)和腺嘌呤(ADP)的包结作用。实验考察了时间、pH值以及温度对荧光强度和包结作用的影响,利用Benesi-Hildebrand方程分别计算出6-MP和ADP与CB[7]的包结常数。结果表明:酸度对体系的包结有明显的影响。在pH值为8.0和2.0左右时,6-MP和ADP分别具有稳定和最佳激发和发射波长,随着CB[7]浓度的增大,体系的荧光强度都有明显增强,包结作用迅速(小于5 min)。实验得出CB[7]与6-MP和ADP的包结比均为1∶1,在298 K时的包结常数分别为3.6797×102L·mol-1和2.2033×102L·mol-1。通过热力学参数的变化,探讨了维系包结物稳定性的主要作用力。CB[7]是葫芦脲家族中水溶性最强的主体分子,作为一种安全低毒的药物载体极具潜力。     

季铵化聚4-乙烯吡啶衍生物与葫芦脲[6]的超分子自组装及性质研究

通过葫芦[6]脲(CB[6])与季铵化聚4-乙烯吡啶衍生物2在水溶液中于室温下进行超分子组装, 得到一种新型的超分子聚合物3, 并通过¹H NMR, IR, 元素分析, X射线粉末衍射分析(XRD)对其结构进行了表征, 证实CB[6]位于2的侧基脂肪链上, 通过非共价键与2结合; 通过热重分析(TGA)、紫外-可见吸收(UV-vis)对其性质进行了研究, 证实了超分子聚合物3比相应的聚合物2有更高的热稳定性, 以及更强的UV-vis吸收.     

光谱法研究羟基葫芦[6]脲与对氨基苯磺酸的分子识别作用

光谱法研究羟基葫芦[6]脲与对氨基苯磺酸的分子识别作用;紫外光谱法;荧光光谱法;分子识别;包结作用;羟基葫芦[6]脲;对氨基苯磺酸     

荧光法研究羟基葫芦[6]脲与水溶性苯胺蓝的分子识别作用

采用荧光光谱法研究羟基葫芦[6]脲(HOCB6)与水溶性苯胺蓝(AB)、荧光素(FS)和甲基紫(MV)之间的包结作用。结果表明,HOCB6与FS和MV无相互作用,而与AB能形成1∶1型的HOCB6-AB内包结物,并测得HOCB6-AB包结物的包结常数为1.02×103L.mol-1。考察了溶液的pH值、常见有机溶剂、表面活性剂和金属离子等对该包结物的形成及荧光强度的影响,初步探讨了它们之间的作用机理。通过选用不同荧光探针作客体,揭示客体分子的大小和空间位阻对主客体包结物的形成具有决定性的影响,在空间匹配的条件下,通过疏水和氢键作用形成稳定的包结物。     

葫芦[7]脲的合成及其与甲基橙的超分子行为研究——综合性研究型实验设计

以尿素为原料合成甘脲,再与甲醛反应合成葫芦脲,然后通过红外、紫外、核磁对其进行表征。详细研究了葫芦[7]脲与甲基橙的超分子包结行为。本实验可使学生接触到超分子化学,有利于学生了解有关葫芦脲的合成方法和包结性质,提高综合分析问题和解决问题的能力。     

A supramolecular bottlebrush polymer assembled on the basis of cucurbit[8]uril-encapsulation-enhanced donor-acceptor interaction

A supramolecular bottlebrush polymer has been constructed in water through the self-assembly of a rigid electron-deficient building block and an electron-rich monomer which bears two tetraethylene glycol chains, driven by CB[8]-encapsulation-enhanced donor-acceptor interaction. The as-formed supramolecular bottlebrush polymer has been characterized by ¹H NMR titration experiment, UV-vis spectroscopy, DLS and 2D ¹H NMR DOSY.     

Cucurbit[8]uril (CB[8])‐Based Supramolecular Switches

The use of cucurbit[8]uril as a molecular host has emerged in the chemical literature as a reliable strategy for the creation of dynamic chemical systems, owing to its ability to form homo‐ and heteroternary complexes in aqueous media with appropriate molecular switches as guests. In this manner, CB[8]‐based supramolecular switches can be designed in a predictable and modular fashion, through the selection of appropriate guests able to condition the redox, photochemical, or pH‐triggered behavior of tailored multicomponent systems. Furthermore, CB[8] allows the implementation of dual/triple and linear/orthogonal stimuli‐dependent properties into these molecular devices by a careful selection of the guests. This versatility in their design gives these supramolecular switches great potential for the rational development of new materials, in which their function is not only determined by the custom‐made stimuli‐responsiveness, but also by the transient aggregation/disaggregation of homo‐ or heteromeric building blocks.     

Tuning thermal gelling behavior of <Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide based copolymer through introducing cucurbit[8]uril ternary complex on side-chain

Thermo-gelation polymers have attracted increasing attention over decades. However, rare facile tuning method of sol-gel transition temperature restricted the wider application. Preceding study indicated that supramolecular interactions demonstrated a powerful means to control the structure and property of polymeric materials. Here we designed an N-isopropylacrylamide (NIPAM) based thermo-sensitive copolymer with naphthyl (Np) on its side chain. Positive-charged side-chain ternary complex was formed with cucurbit[8]uril (CB[8]) and methylviologen (MV²⁺) via CB[8]-enhanced intermolecular charge-transfer (CT) interaction. Introducing the ternary complex CB[8]/MV²⁺/Np on side-chain altered microstructure of macromolecular chains and led to a strong tendency for thermo gelation. Altering content of CB[8] and MV²⁺ changed content of the positive-charged side-chain ternary complex and varied gelation temperature. Therefore, introducing supramolecular interaction endowed the hydrogel with tunable gelation property.     

Dimension-Controllable and Photo-Responsive Supramolecular Organic Framworks through Cucurbit[8]uril-based Self-Assembly

Dimension-controllable supramolecular organic frameworks (SOFs) with aggregation-enhanced fluorescence are hierarchically fabricated through the host-guest interactions of cucurbit[8]uril (CB[8]) and coumarin-modified tetraphenylethylene derivatives (TPEC). The three-dimensional layered SOFs could be constructed from the further stacking of two-dimensional mono-layered structures via simply regulating the self-assembly conditions including the culturing time and concentration. Upon light irradiation under the wavelength of 365 nm, the photodimerization of coumarin moieties occurred, which resulted in the transformation of the resultant TPEC\begin{document}$ _n $\end{document}/CB[8]\begin{document}$ _{4n} $\end{document} two-dimensional SOFs into robust covalently-connected 2D polymers with molecular thickness. Interestingly, the supramolecular system of TPEC\begin{document}$ _n $\end{document}/CB[8]\begin{document}$ _{4n} $\end{document} exhibited intriguing multicolor fluorescence emission from yellow to blue in the time range of 0\begin{document}$ - $\end{document}24 h at 365 nm irradiation, possessing potential applicability for photochromic fluorescence ink.     

Sequential Formation of Heteroternary Cucurbit[10]uril (CB[10]) Complexes

The globular and monocationic guest molecule trimethyl-azaphosphatrane ( AZAP , a protonated Verkade superbase) was shown to form a host:guest 1 : 1 complex with the cucurbit[10]uril (CB[10]) macrocycle in water. Molecular dynamics calculations showed that CB[10] adopts an 8-shape with AZAP occupying the majority of the internal space, CB[10] contracting around AZAP and leaving a significant part of the cavity unoccupied. This residual space was used to co-include planar and monocationic co-guest ( CG ) molecules, affording heteroternary CB[10]⋅ AZAP ⋅ CG complexes potentially opening new perspectives in supramolecular chemistry.     

紫精与八元瓜环的超分子组装及光切割质粒DNA

利用紫精可以活化水中溶解氧的特性, 设计合成了苯-紫精化合物(BEV). 利用紫外吸收、电化学及核磁等方法研究了BEV与八元瓜环CB[8] 之间的相互作用. 实验结果表明, 2种化合物可以进行主客体超分子自组装形成1∶ 1的二元包合物BEV-CB[8]. 同时, 分别考察了化合物BEV和BEV-CB[8]与小牛胸腺DNA的相互作用, 并采用琼脂糖凝胶电泳研究了氙灯光照下化合物对pBR322 DNA的切割能力. 结果表明, CB[8]的引入改变了化合物BEV与DNA的作用方式, 使嵌入作用和静电作用增强. 光照结果说明只有超分子BEV-CB[8]在光照下可以完全切割质粒DNA, 即CB[8]的存在明显提高了BEV对质粒DNA的切割效率.     

A fluorescent guest used to determinate the effective content of CB[8] and to further detect methyl viologen

A fluorescent pyrene derivate,N-allyl-1-pyrenemethylammonium hydrochloride(APA+),was reported to form a stable host–guest complex with cucurbit[8]uril(CB[8]),and this property can be utilized to determinate the purity of CB[8]via emission titration.Moreover,the 1:1 complex of APA+and CB[8]can further bind methyl viologen(MV2+),which is the main ingredient of a widely used herbicide,providing a good method to detect MV2+,especially at low concentrations.     

Chiral Adaptive Induction of an Achiral Cucurbit[8]uril-Based Supramolecular Organic Framework by Dipeptides in Water

Chiral induction by natural biomolecules can reveal the indispensable role of chiral structures in life and can be used to develop the chirality-sensing biomolecular recognition. Here, we present the synthesis and characterization of an achiral supramolecular organic framework ( SOF-1 ) constructed from cucurbit[8]uril (CB[8]) and hexaphenylbenzene (HPB) derivative ( 1 ) in water. Due to the propeller-like rotational chiral conformation of HPB units and the specific recognition properties of CB[8], SOF-1 demonstrates chiral adaptive induction in water when interacting with the N-terminal Trp-/Phe-containing dipeptides including L-TrpX and L-PheX (X is an amino acid residue), respectively, exhibiting contrasting circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. Consequently, SOF-1 has been developed as a supramolecular host and chiroptical sensor capable of recognizing and distinguishing the sequence-opposite Trp-/Phe-containing dipeptide pairs including L-TrpX/L-XTrp and L-PheX/L-XPhe based on the sequence-selective CD responses.     

Supramolecular assembly of cucurbit[6]uril and N-butyl-4-pyrrolidinopyridine

The nature of the supramolecular host–guest complex involving 4-pyrrolidinopyridine (BuPC4) and cucurbit[6]uril (Q[6]) has been investigated by NMR and UV spectroscopy, MALDI-TOF mass spectrometry, X-ray crystallography and isothermal titration calorimetry. The results revealed that the alkyl chain of the guest BuPC4 is located inside the cavity of the Q[6] host, whereas the other section of the BuPC4 guest remains outside of the portal.     

基于甲壳型液晶高分子的刚-柔型二嵌段共聚物的层状相:链伸展行为的研究

研究了一系列以聚己内酯(PCL)为柔性链段、甲壳型液晶高分子聚{2,5-二[(4-甲氧基苯基)氧羰基]苯乙烯}(PMPCS)为刚性链段的刚-柔型二嵌段共聚物(PCL-b-PMPCS)的微相分离结构.小角X射线散射(SAXS)和广角X射线衍射(WAXD)实验结果表明,当PMPCS为无定形态时,PCL-b-PMPCS的微相分离行为与柔-柔型二嵌段共聚物相似,其相形态主要取决于两段的体积分数.随温度升高,PMPCS链段采取伸展的棒状构象,形成六方柱状向列相(ΦHN),会诱导体系的微相分离结构出现"有序-有序"或"无序-有序"转变,使得在很宽的PMPCS体积分数(fPMPCS:40%~80%)内样品均呈现层状微相分离结构.我们对在200oC得到的层状相SAXS数据进行了一维相关函数分析,详细考察了层状相中PMPCS及PCL相区的厚度(LPMPCS、LPCL)与相应链段聚合度(NPMPCS、NPCL)的关系.对PMPCS相区,发现LPMPCS=0.2NPMPCS(nm).因棒状PMPCS链段与层的法线方向平行,该线性关系表明PCL-b-PMPCS的层状相为"单层近晶A相"结构,LPMPCS即为棒状PMPCS链段的长度,可通过控制PMPCS的聚合度予以精确控制.对PCL相区,则LPCL与NPCL近似有标度关系LPCL~NPCL0.85,说明处于熔融态的PCL链段受迫强烈伸展.进一步分析WAXD实验数据并计算每根PMPCS链段在层状相中的界面面积(S/X)可知,随NPMPS增大,PMPCS链段的液晶度从~20%增至~55%,S/X则从~2.4nm2增至~2.7 nm2.与此相应,PCL链段的伸展程度会略有降低,说明LPCL有较弱的NPMPCS依赖性.另一方面,LPCL与S/X的乘积与NPCL满足线性关系LPCL(S/X)=0.21NPCL(nm3),斜率即为PCL重复单元的体积.