Study On The Supramolecular Self-assembly And Host-guest Interaction Of Cyclopentyl Cucurbit

In this study,we investigated the interaction of a fully substituted cyclopentano cucurbit[6]uril?CyP₆Q[6]?with alkaline earth cations(AE²⁺)and corresponding supramolecular assemblies in the presence of tetrachloridozincate anions([Zn?H₂O?Cl₃]^-or[ZnCl₄]^2-).Single-crystalX-raydiffractionanalysisrevealedthatthe CyP₆Q[6]-Mg²⁺-ZnCl₂-HCl interaction system yielded an adduct of[Mg?H₂O?₆]²⁺with CyP₆Q[6].The CyP₆Q[6]-Ca²⁺,Sr²⁺and Ba²⁺-ZnCl^2--HCl interaction systems yielded linear AE²⁺/CyP₆Q[6]/AE²⁺-type coordination polymers that filled the cells in the[ZnCl₄]^{2_</sup>-based honeycomb-like framework.Unlike unsubstituted Q[n]systems in which[ZnCl₄]2-anions surround Q[n]molecules via outer surface interaction of Q[n],electrostatic interactions between[ZnCl₄]2-anions and the coordinated AE2+cations results in the formation of[ZnCl4]2--based honeycomb-like frameworks.Coordinationandsupramolecularassembliesofafullysubstituted cyclopentanocucurbit[6]uril?CyP₆Q[6]?with a series of lanthanide cations(Ln3+)have been investigated in the presence of tetrachlorozincate anion([ZnCl₄]2-).X-ray single crystal diffraction analysis has revealed that the interaction of CyP₆Q[6]and a series of Ln3+cations unexpectedly results in the formation of at least seven different CyP₆Q[6]-based coordination complex adduct and supramolecular assemblies groups,including with 1)La3+,Ce3+cations;2)Pr3+,Nd3+cations;3)Eu3+,Gd3+,Tb3+,Dy3+with P-1 or P1 space group,in which CyP₆Q[6]molecules coordinate alternatively with Ln3+cations and form linear coordination polymers;4)CyP₆Q[6]molecules interact alternatively with[Ho?H₂O?₈]3+aqueous complexes and form linear supramolecular chains;CyP₆Q[6]molecules can assemble two different Ln3+free porous supramolecular assemblies from CyP₆Q[6]–Ln?NO₃?₃–ZnCl₂–HCl systems,Ln=Tm,Yb and Lu;however,no solid crystals were obtained from system containing Er3+cation.Thus,these differences could lead CyP₆Q[6]to be useful in not only the isolation of lighter lanthanides from their heavier lanthanides but also special selectivity for different volatile organic compounds.The binding interactions of CyP₆Q[6]with a series of alkyl diammonium?+H₃N?CH₂?_nNH₃+,n=2,4,6,8,10,12?and aryl diammonium?p-phenylenediammonium and p-xylenediammonium?ions both in aqueous solution and solid state have been studied by1H NMR spectroscopy,X-ray crystallography,and isothermal titration calorimetry?ITC?techniques.1H NMR data indicate that all guests exhibit endo binding with CyP₆Q[6]except for the ethanediammonium ion,which bound exo to CyP₆Q[6].p-xylenediammonium ions shows mixed behavior?exo and endobinding with CyP₆Q[6]?.X-ray crystallography clearly display the extended and contorted conformations of the guests when bound within CyP₆Q[6].ITC study points out that the CyP₆Q[6]complex formations with all guests are mainly driven by enthalpy,which arises from the ion–dipole interactions and the hydrophobic effects.}