Cucurbit[8]uril-regulated face-to-face dimerization assembly enhanced photosensitization and photocatalysis

In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests(G1–G3) were encapsulated by cucurbit[8]uril(Q[8]) to construct Q[8]_(3)/G_(2) complexes, in which the encapsulated G molecules exist as an exact face-to-face dimer. These complexation behaviors have been indicated by proton nuclear magnetic resonance(~1H NMR) spectroscopy and isothermal titration calorimetry(ITC),and have been confirmed by X-ray single crystal structural analysis of Q[8]_(3)/G2_(2). While free guests G1–G3 have no ability to sensitize singlet oxygen, they all become effective singlet oxygen sensitizers when complexed with Q[8]. By irradiation of white light, Q[8]_(3)/G_(2) complexes induced selective oxidation of aryl sulfide to aryl sulfoxide in good yields and selective oxidation of dimethyl sulfide(DMS) to dimethyl sulfoxide(DMSO) in excellent yields without over-oxidation to dimethyl sulfone(DMSO_(2))even for elongated irradiation. High-yield photo-oxidation of DMS to DMSO_(2) was only achieved by irradiation of blue light in the presence of Q[8]_(3)/G1_(2), which was also effective in photobleaching of Rhodamine B in water. The higher photo-oxidation power of Q[8]_(3)/G1_(2) has been ascribed to an additional generation of reactive oxygen species besides singlet oxygen.

Tunable organic particles:An efficient approach from solvent-dependent Schiff base macrocycles

The synthesis of cyclopolymers upon controlling the degree of macrocyclic polymerization,followed by the discovery of new properties has attracted increasing attention in supramolecular chemistry.Herein,a Schiff-base condensation method performed at room temperature was used to control the formation of[1+1]and[2+2]macrocycles.In pure MeOH,the isomer[1+1]macrocycles were synthesized and organic particles such as dendritic,rods,and solid microspheres were directly precipitated from the reaction solution.The[1+1]macrocycles can be efficiently converted into their corresponding[2+2]macrocycles accompanied by the tunable morphology of the organic particles when n-hexane was added to the MeOH solution.Further studies showed that these organic particles have potential application toward the selective removal of Cd^(2+)ions with different adsorption ability in MeOH solution.

Host-guest interaction tailored cucurbit[6]uril-based supramolecular organic frameworks(SOFs) for drug delivery

An approach for the construction of crystalline porous supramolecular organic frameworks (SOFs) via outer-surface interactions of cucurbit[6]uril (Q[6]) with high yield is presented. This approach enables the noncovalent integration of guest molecules into ordered topologies and creates new host-guest-complex-based SOFs;i.e., the topology can be predesigned and constructed by using [ZnCl_(4)]^(2-) anions to induce the formation of solid Q[6]-SOFs, and the pore wall surface can be easily modified by the Q[6]-encapsulated guest molecules. In addition, one of prepared solid Q[6]-SOFs showed a high drug-loading capacity and smart potential release control for drug-delivery applications.

Unprecede nted tunable hydrophobic effect and anion recognition triggered by AIE with Hofmeister series in water

An un precedented tun able hydrophobic effect in self-assembly of a small cationic organic fluorophore(NI-TPy^(+))-based with aggregation-induced emission(AIE)property was realized in aqueous solution.The amplification of hydrophobicity was found to be significantly dependent upon the increasing aggregates of NI-TPy^(+),which enabled the study of the hydrophobic binding of chaotropic anions with the Hofmeister series.

Involvement of unusual noncovalent interactions in the self-assembly of cucurbit[6]uril with [CdCl_4]^(2-) anions

The [CdCl_4]^（2-） anion as a structure inducer has proved to be useful in the construction of cucurbit[n]urilmetal coordination architectures and materials. In order to better understand the role and influence of the structure inducer in Q[n] systems, we report herein the self-assembly of Q[6] solely in the presence of[CdCl_4]^（2-）anions and in the presence of both a linear cationic organic guest and [CdCl_4]^（2-）anions. X-ray diffraction analysis revealed that 1D Q[6] porous channels were formed by the noncovalent interactions between Q[6] and [CdCl_4]^（2-）anions, but the ＇＇honeycomb effect＇＇ was not observed in the present study.However, it seems that the ＇＇honeycomb effect＇＇ and the self-assembly of Q[6] with [CdCl_4]^（2-）anions can be significantly modified and switched in the presence of a linear cationic dibutylamine guest through some unusual noncovalent interactions.

pH-Switched fluorescent pseudorotaxane assembly of cucurbit[7]uril with bispyridinium ethylene derivatives

The host-guest properties of cucurbit[7]uril （0_[7]） and bispyridinium ethylene derivatives have been studied by 1H NMR spectroscopy, UV-vis absorption spectra, and fluorescence emission analysis. The proton shifts associated with the guest encapsulated by the host suggested that the Q[7]-based [2] pseudorotaxane behaves like a fast molecular shuttle along the bispyridinium ethylene axle of the guest upon protonation and deprotonation of the terminal carboxylates. In particular, the distinct fluorescent response signals indicated that the bispyridinium component for the pseudorotaxane system, but also ~uest comDlexation. ethylene moiety not only behaves as the axle acts as an optical reporting unit during the host-

Complexation of sym-bis(benzimidazole)-2,2'-ethylene salts with cucurbit[6]uril derivatives:A potential axle molecule for pseudorotaxanes

Sym-bis（benzimidazole）-2,2＇-ethylene cations act as a new axle template for threading cucurbit[6]uril derivatives on,forming[2]pseudorotaxane and[3]pseudorotaxane.These new complexes have been studied using 1 H NMR,UV-vis absorption spectroscopy and X-ray analysis.Changes in the 1 H NMR spectra indicate that the two types of pseudorotaxane can be formed by varying the host concentration. UV-vis absorption titration experiments at different pH values demonstrate that interesting pK_a shifts of the bis-benzimidazole derivatives can be induced by the host-guest complexation.The associated constants were calculated to be 2.81×10^4 L/mol and 9.06×10^6 L/mol for the[2]pseudorotaxanes and ｜3]pseudorotaxanes,respectively.Furthermore,X-ray diffraction studies of the solid state structures provide unequivocal proof of the host concentration dependent pseudorotaxane,which is strongly in line with the evidences in solution.

Controllable fabrication of a supramolecular polymer incorporating twisted cucurbit[14]uril and cucurbit[8]uril via self-sorting

A linear supramolecular polymer with controllable features based on twisted cucurbit[14]uril(tQ[14])and cucurbit[8]uril(Q[8])was firstly fabricated via an effective self-sorting strategy.Herein we designed a monomer,1–butyl–1?-(naphthalen-2-ylmethyl)-4,4?-bipyridinium bromide(BNB),that contains bipyridyl,aliphatic butyl and aromatic naphthyl groups,simultaneously.Two host molecules,tQ[14]and Q[8]were employed to develop an effective strategy for constructing a linear supramolecular polymer with con-trollable features.The alkyl groups on both sides of BNB could insert into the two cavities of tQ[14],the naphthyl part of BNB viaπ-πstacking in Q[8]cavity,serving as the driving force for supramolecular polymerization.Through self-sorting of the monomer,tQ[14]and Q[8],led to the formation of the linear supramolecular polymer.Depolymerization could be achieved by addition of adamantane hydrochloride(AH)which driven two BNB guest molecules out of the Q[8]cavity.This self-sorting strategy has great potential,not only for designing supramolecular polymer materials with different controllable structures through introduction of multiple functional groups,but also for broadening the application of twisted cucurbit[14]uril in supramolecular chemistry.