Synthesis, Separation, Oxidation And Supramolecular Self-assembly Of Partially Methyl Substituted Melon Rings

Cucurbit[n]urilis?Q[n]s?,a kind of relevant new macrocyclic compounds emerging from the field of supramolecular chemistry besides crown ethers,cryptands,cyclodextrins,and calixarenes.Q[n]s are characterized by their highly symmetrical hydrophobic cavities and hydrophilic carbonyl portals.However,as a class of host molecules in the field of supramolecular chemistry,the special chemical stability prevents the preparation of functionalized Q[n]s in high purity,particularly,for larger Q[n]s and alkyl substituted Q[n]s.Therefore,the research of the synthesis and separation of functionalized Q[n]s has become an important research area of Q[n] chemistry.In this work,mono-and di-hydroxylated symmetrical octamethylcucurbit[6]urils{?OH?OMeQ[6] and trans-?OH?₂OMeQ[6]} were prepared using a photochemical method to introduce limited alcohol group?s?directly to their parent symmetrical octamethylcucurbit[6]uril?OMeQ[6]?,and the resulting compounds were verified by1 HNMR,Xevo Q-TOF MS,and X-ray crystallography.Allylation could be readily carried out on the mono-and di-hydroxylated hydroxyl group for the furher chemical modification.This could open up a new avenue for controlling the chemical modification of Q[n],especially larger Q[n]s or alkyl-substituted Q[n]s.Coordination of cucurbit[n]urils?Q[n]s?to metal ions through their portal carbonyl oxygen atoms constitutes an important research area,that is,Q[n]-based coordination chemistry,which has developed greatly in the last decade.Design and synthesise a series of supramolecular polymers based on direct coordination of metal ions to the cucurbit[n]urils by using an induced strategy is a new research direction in the Q[n]-based coordination chemistry.the back-intractions include 1)electrodonating effect of the alkyl-substituted groups on the back of cucurbit[n]urils;2)p???p stacking between portal carbonyl groups of cucurbit[n]uril as well as C–H??? p interaction between methine or methylene moieties on the back of cucurbit[n]urils and aromatic moiety of organic structure inducers;3)unusual hydrogen bonding between methine or methylene moietieson the back of cucurbit[n]urils as well as ion-dipole interactions between positive portal carbonyl carbon of cucurbit[n]urils and chloride anion from polychlorometallate anions;4)coordination interaction between hydroxyl groups on the back of cucurbit[n]urils with metal ions.The interaction of the alkaline-earth metal ions with the symmetricaloctamethyl-substituted cucurbituril,OMeQ[6],in the presence of [CdCl4]2-/[Cd2Cl8]4-anions as structure-directing agent?s?in HCl solution has been investigated.Interaction of the larger Ba²⁺ ion with OMeQ[6] gives rise to a different assembly type displaying a porous linear polymer arrangement.Its absorption profile shows maximum absorption for methanol.The interaction of OMeQ[6] with alkali metal ions has been investigated in the presence of different structure-directing agents such as CdCl2 or p-hydroxybenzoic acid?Hyb?,and there were a variety of modes of interaction,it showed that in the presence of these different structure-directing agents,OMeQ[6] or OMeQ[6]/A⁺complexes can form different supramolecular assemblies based on the outer surface interaction of Q[n].And then the interactions of alkali metal?A?cations with mono-hydroxylated octamethylcucurbit[6]uril {?OH?OMe Q[6]} have been investigated.It results in the formation of?OH?OMeQ[6]-based coordination complexes from?OH?OMeQ[6]–ACl–CdCl2–HCl systems.