Molecular recognition properties of acyclic cucurbiturils toward amino acids,peptides, and a protein

The binding of 1 and 2 toward 19 amino acid amides by ¹H NMR and ITC is reported. Hosts 1 and 2 bind to aromatic or hydrophobic residues by cavity inclusion leaving the cationic residues at the C=O portals. K_a values range from 10² to >10⁶ M^?1 with H-Phe-NH₂, H-Trp-NH₂, and H-Tyr-NH₂ displaying sub-micromolar K_d values. Hosts 1 and 2 bind tightly to dicationic H-Lys-NH₂ and H-Arg-NH₂ which are poor guests for CB[7]. Comparison of the affinity of 1 and 2 toward the amino acid amide, N-acetyl-amino-acid amide, and amino acid forms of Phe revealed that the removal of the NH₃⁺ to O=C and SO₃^? electrostatic interactions costs 3.8 kcal/mol whereas the introduction of an unfavourable CO₂^? to O=C and SO₃^? electrostatic interactions costs 2.1 kcal/mol. Hosts 1 and 2 bind to insulin with low micromolar affinity. Acyclic CB[n] display high affinity toward a wider range of N-terminal amino acids residues than CB[n] which suggests a broad range of applications.     

Molecules-Receptors: Different Approaches to Design Effective Catalysts

The results of studying a number of reactions catalyzed by system based on macrocyclic receptors are presented. Rh complexes with modified calix[6]- and calix[4]arene were active in the hydroformylation of unsaturated compounds. Ru catalytic system based on cucurbit[6]uril was studied in hydrogen transfer hydrogenation of water insoluble aldehydes. Molecular imprinting method application for design of catalytic systems based on cyclodextrins for naphthols dimerization and oxidative coupling styrene and benzene were discussed.     

Synthesis and the crystal structure of a supramolecular adduct of the [Mo3O4(H2O)6Cl3]+ cluster complex with macrocyclic cavitand cucurbituril

The crystalline supramolecular compound of composition {(C₃₆H₃₆N₂₄O₁₂)[Mo₃O₄(H₂O)₆Cl₃]₂}Cl₂·14H₂O was obtained by slow concentration of a hydrochloric solution of the cluster aqua complex [Mo₃O₄(H₂O)₉]⁴⁺ and macrocyclic cavitand cucurbituril (C₃₆H₃₆N₂₄O₁₂). The molecular and crystal structure of the supramolecular adduct was established by X-ray diffraction analysis.     

Synthesis and crystal structure of supramolecular adduct of tetranuclear uranyl chloride aquacomplex with macrocyclic cavitand cucurbituril

Crystals of supramolecular compound {[(UO₂)₄O₂Cl₄(H₂O)₆](H₂OC₃₆H₃₆N₂₄O₁₂)}·4H₂O were obtained under conditions of hydrothermal synthesis from solutions of uranyl(vi) nitrate and cucurbituril in the presence of rubidium chloride. The crystal and molecular structure were determined by X-ray diffraction analysis.     

Synthesis and the crystal structure of the supramolecular complex [Cl3InW3S4(H2O)9]2+ with cucurbituril

The supramolecular complex {[Cl₃InW₃S₄(H₂O)₉]₂(C₃₆H₃₆N₂₄O₁₂)}Cl₄·28H₂O was prepared by mixing solutions of [Cl₃InW₃S₄(H₂O)₉]²⁺ and cucurbituril in hydrochloric acid. The molecular and crystal structure of the resulting complex was established by X-ray diffraction analysis.     

Complex Formation of Crown Ethers with the Cucurbit[6]uril–Spermidine and Cucurbit[6]uril–Spermine Complex in Aqueous Solution

Alkyl amines are able to form complexes with either crown ethers or cyclodextrins or cucurbit[6]uril. The same is known for polyamines such as spermidine and spermine. However, the simultaneous formation of such polyamines with crown ethers and cucurbit[6]uril has not been studied. The ability of polyamines such as spermidine and spermine to form mixed complexes with different ligands, e.g. crown ethers and cucurbit[6]uril has been studied in aqueous solution using pH-metric and calorimetric titrations. The thermodynamic data of reaction between crown ethers with spermidine, spermine and their cucurbit[6]uril complexes have been determined. The presence of cucurbit[6]uril on the polyamines has no important influence upon the reaction of these amines with crown ethers. The reactions between polyamines, cucurbit[6]uril and crown ethers are simple examples for the self organization of molecules due to specific interactions. Received in final form: 26 January 2005     

Synthesis and Crystal Structure of Cucurbit[6]uril Adduct of Hydrogen-bonded Cluster Complex [Mo3(μ3-Se)(μ2-O)3(H2O)6Cl3]+

Reaction of [MoOCl₅]²⁻ with in situ generated H₂Se under hydrothermal conditions (4M HCl, 140 °C) leads to reduction of Mo(V) to Mo(IV) with the formation of a triangular cluster Mo₃(μ₃-Se)(μ-O)₃⁴⁺ in high yield. It is present in HCl solutions as aqua chlorocomplex [Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]⁺ which was isolated and structurally characterized as supramolecular adduct with cucurbit[6]uril (CB[6]), {[Mo₃(μ₃-Se)(μ-O)₃(H₂O)₆Cl₃]₂CB[6]}Cl₂·15H₂O. Dedicated to Professor Dieter Fenske on the Occasion of his 65th Birthday     

钡离子驱动荧光准轮烷

含有水溶性季铵盐基团的4-正己氨基-1,8-萘酰亚胺化合物在水中与葫芦脲[6]通过疏水及氢键作用形成准轮烷结构,而且体系荧光波长红移了17nm,荧光强度降低32%.研究表明,往准轮烷溶液中加入与葫芦脲[6]具有强结合力的Ba2+离子会使准轮烷结构离解,体系荧光恢复;而再往溶液中加入SO42-,Ba2+以BaSO4沉淀的形式被除去,这时准轮烷又重新生成.核磁氢谱、紫外-可见吸收光谱、荧光光谱和荧光寿命对体系的结合/离解过程的研究表明这种结合/离解过程是可逆的.本体系可以模拟插头/插座的连接和断开动作.     

Supramolecular Assemblies with Near‐Infrared Emission Mediated in Two Stages by Cucurbituril and Amphiphilic Calixarene for Lysosome‐Targeted Cell Imaging

A two‐stage mediated near‐infrared (NIR) emissive supramolecular assembly for lysosome‐targeted cell imaging is presented. 4,4′‐Anthracene‐9,10‐diylbis(ethene‐2,1‐diyl))bis(1‐ethylpyridin‐1‐ium) bromide (ENDT) was synthesized as an organic dye with weak fluorescence emission at 625 nm. When ENDT complexes with cucurbit[8]uril (CB[8]), this binary supramolecular complex assembles into nanorods with a near‐infrared fluorescence emission (655 nm) and fluorescence enhancement as the first stage. Such supramolecular complexes interact with lower‐rim dodecyl‐modified sulfonatocalix[4]arene (SC4AD) to form nanoparticles for further fluorescence enhancement as the second stage. Furthermore, based on a co‐staining experiment with LysoTracker Blue, such nanoparticles can be applied in NIR lysosome‐targeted cell imaging.