The Semi-cucumber Ring Interacts With The Host And Object Of The Electrically Neutral Object

The host-guest interactions between electron neutral small molecules and Hemi Q[6 or12] have been studied in this work.The o-,m-,and p-aminophenols(Guest1,Guest2,Guest3),Schiff-base made salicylaldehyde(Guest4)and ferrocene(Guest5)have been employed as the guests,and the host-guest interactions with Hemi Q[6 or 12] have been characterized by means of 1H NMR,13 C NMR,UV-vis,fluorescence spectroscopy,isothermal titration calorimetry,quantitative calculation and cyclic voltammetry.The host-guest interactions between o-,m-,and p-aminophenols and hemicucurbit[6 and 12]urils have been investigated by using 1H NMR spectrometry and isothermal titration calorimetry.The 1H NMR spectra support the interactions between guests and hemicucurbiturils,and the thermodynamic data obtained from isothermal titration calorimetry indicate the formation of host-guest interactions between the hemicucurbiturils and aminophenols in a ratio of 1:1.The host-guest interactions of hemicucurbit[6 and 12]urils with the Schiff-base guest4 has been investigated.1H NMR spectra suggest hemicucurbit[6 and 12]urils bind to guest 4 by the formation of hydrogen bonds between the phenol hydroxyl group of guest 4 and carbonyl groups on the hosts.The formation of interaction complexes are also supported by fluorescence emission spectroscopy.The moderate association constants of the interaction complexes in a ratio of 1:1 are obtained to be(3.2 ±0.6)×105 L mol-1 for Hemi Q[6] host and(5.5 ±0.8)×105 L mol-1 for Hemi Q[12],respectively,via non-linear curve fitting,which illumine that the formation of hydrogen bonds are important in the host-guest interactions.The supramolecular interaction between Hemi Q[6] and ferrocene was investigated using 1H and 13 C NMR spectroscopy,cyclic voltammetry(CV),ITC and quantum chemistry.The results from 1H NMR,13 C NMR spectra and Cyclic voltammetry confirm the host-guest interaction.Isothermal titration calorimetry provides thermodynamic data for the host-guest interaction and an association constant of Ka =4.9×104 L mol-1 in a 1:1 ratio has been obtained.Quantum chemistry suggests the encapsulation complex was stabilized by the formation of hydrogen bond between the aromatic protons on the ferrocene guest and the carbonyl groups on hemicucurbit[6]uril,and therefor,the electron transfer of the interaction complex was more easy than that in free ferrocene.