Synthesis of Copillar[5]arenes and Their Host-Guest Complexation with Two Types of Guests

A series of novel copillar[5]arenes 1a-1f containing different substituents were synthesized.And their com-plexation with two types of guests was investigated.For symmetrical guests,1,4-dibromobutane(DBB)could thread in the cavity of copillar[5]arenes to form inclusion complexes.But for the unsymmetrical guests,copillar-[5]arene 1f bearing 4-(naphthalen-1-yloxy)butoxy could not complex with sec-butyl iodide(SBI)and sec-butyl bromide(SBB)at all,while 1f showed weak interaction with sec-butylamine•HCl(SBA)outside the cavity.These results indicated that the modified group of copillar[5]arene and the symmetry of guest played an important role in the complexation model and selectivity.

新型二酰胺穴醚与吡啶N-氧化物的络合作用研究

通过大环化合物4和9分别与5-叔丁基间苯二甲酰氯反应得到了新型穴醚5和10,并通过氢谱、碳谱、低分辨质谱和高分辨质谱进行了结构表征.采用ESI-MS和1H NMR方法研究了主体化合物穴醚5和10与客体吡啶N-氧化物的相互作用,通过核磁滴定测定了主客体络合物的络合常数.结果表明:穴醚5和10都能与吡啶N-氧化物形成1∶1络合物,而且对于相同的客体,环状"空腔"较大的主体化合物10的络合常数Ka比主体化合物5的络合常数大23倍.

Pagoda[5]arene with Large and Rigid Cavity for the Formation of 1∶2 Host-Guest Complexes and Acid/Base-Responsive Crystalline Vapochromic Properties

Pagoda[5]arene(P5),which is composed of five 2,6-dimethoxylanthracene(2,6-DMA)subunits bridged by methylene groups at 1,5 positions,was conveniently synthesized in 43%by trifluoroacetic acid(TFA)-catalyzed one-pot condensation of commercially available 2,6-DMA and paraformaldehyde in 1,2-dichlorobenzene(o-DCB)at room temperature.P5 showed a highly symmetrical pentagonal structure with a large and deep electron-rich cavity,which made it form stable 1∶2 host–guest complexes with various aryl-pyridinium,bipyridinium,and stilbazolium salts in solution.Interestingly,P5 could complex two or even three guests with its intrinsic cavity and the pseudocavity formed by the adjacent macrocycles in solid states.Moreover,the strong intermolecular charge-transfer(ICT)interactions between P5 and the guests were observed.Especially,the complexes formed by P5 and the protonated pyridinium or bipyridinium salts showed acid/base-responsive color changes in solution and remarkable crystalline vapochromic properties by two kinds of processes:from ICT to no ICT and from ICT to enhanced ICT interaction or vice versa.We believe that the easily available P5 with the specific structure and intriguing 1∶2 host–guest complexation can find wide application in supramolecular assemblies and functional materials.

Theoretical Study on the Conformational Conversion of 1,3-Dioxane Inside a Capsular Host

The mechanism for the conformational conversion of 1,3-dioxane guest encapsulated inside a capsular host was theoretically investigated using semiempirical PM3 method and DFT methods. The free-state process of the conformational conversion of 1,3-dioxane was also investigated to make a comparison between the two different states using the same theory. The influences of the inner phase of the capsule on the conformational conversion of guest molecule were discussed via analyzing the comparative results. It was found that the capsular host could accommodate 1,3-dioxane within its cavity by the weak attractive interactions between host and guest, and it responds to the conformational conversion of guest by the deformation of hydrogen-bonding seam at the middle of the capsule. When entrapped in the capsule, the guest molecule undergoes the conformational conversion from chair form to twist-boat form slower than that under the free condition. The deformation of the capsule is favorable to maximize the attractive interactions between host and guest.

Complexation Selectivities of Pillar[5]arenes with Primary Ammonium Salts

The complexation of alkyl-substituted pillar[5]arenes with primary ammonium salts is investigated. 1,4-Bis- （methoxy）pillar[5]arene （MeP5） can form strong complexes with the primary ammonium salts in CDC13. However, 1,4-bis（ethoxy）pillar[5]arene （EtP5） shows weak interaction with these guests, and 1,4-bis（butoxy）pillar[5]arene （BuP5） can not form such a complex at all. These results indicate that the modified alkyl chains of pillar[5]arene play an important role in the complexation selectivity.

Host-Guest Interactions of Cyclopentanocucurbit[6]uril with Alkyl Imidazolium Hydrochlorides

The host-guest interactions between cyclopentanocucurbit-[6]uril(CyP_(6)Q[6])as host and six alkyl imidazolium hydrochloride as guests(g1,g2,g3,g4,g5,and g6)have been studied by various techniques,such as^(1)H NMR spectroscopy,isothermal titration calorimetry,mass spectrometry,and single-crystal X-ray diffraction analysis.The experimental results showed that CyP6Q[6]formed 1:1 inclusion complexes with each of guests g1-g6.The part of the guest entered the cavity of CyP_(6)Q[6]changes as the alkyl chain increases in length.It can be seen that the length of the alkyl chain plays a key role in determining the mode of host-guest interactions.

Studies on the Intramolecular Inclusion Complexes of Functionalized Calixarenes with CH_3X (X=CN, NO_2)

Two functionalized calixarenes in cone conformation L 2-3 have been synthesized and their intramolecular inclusion complexes (1∶1) with organic neutral molecules CH 3CN and CH 3NO 2 have been prepared and characterized, respectively. The X-ray crystallographic analysis shows that L 2 in L 2·CH 3CN·C 2H 5OH has C 4 symmestry and L 3 in L 3·CH 3NO 2 exhibits C 2 symmestry. The CH-π aromatic interactions between the CH group of the guest and the phenyl rings of the calix backbond have been proved to be able to stabilize the intramolecular inclusion complexes formed. The interaction is directional, but it is independent of the acidity of the guest. To gain information on CH-π interactions, suitable geometrical parameters have been calculated from the crystal data of intramolecular inclusion complexes. The results show that L 3·CH 3NO 2 with L 3 in C 2 symmestry can also be bound stably in the intramolecular inclusion complex, being consistent with the thermal analysis. The geometrical parameters and the results of the thermal analysis of L 1·CH 3CN and L 1·CH 3NO 2 were also given and discussed.

Cucurbit[7]uril/CuCl promoting decomposition of 4-nitrobenzenediazonium in aqueous solution

4-Nitro-benzendiazonium (4-NBD) was found to form a 1:1 host-guest complex (NBD@CB) with cucurbit[7]uril (CB[7]) in aqueous solution and 4-NBD enters into the cavity of CB[7] with a binding constant of1.28 x 10~5 L/mol. NBD@CB can be decomposed into a nitrobenzene/4-nitrophenol mixture in a high total yield (61 %+ 33%) in the presence of CuCl, unlike the decomposition of 4-NBD in the presence of either CB[7] or CuCl, or both absence, where would result in significant amounts of unknown byproducts. This work might provide an economic and effective way to obtain arenes or phenols through the substitution of diazonium salts.

Construction of Supramolecular Architectures via Self-assembly

1 Results In this paper we report supramolecular polymeric nano networks formed by the molecular-recognition-directed self-assembly between a calix[5]arene and C60[1]. Covalently-linked double-calix[5]arenes take up C60 into their cavities[2]. This complementary interaction creates a strong non-covalent bonding; thus,the iterative self-assembly between dumbbell fullerene 1 and ditopic host 2 can produce the supramolecular polymer networks (See Fig.1).

Metal-organic supramolecular nanoarchitectures by Ru(Ⅱ)bis-(terpyridine)-bridged pillar[5]arene dimers with triphenylamine

A metal-organic photoinduced electron transfer(PET) supramolecular nanoarchitecture comprised of Ru(Ⅱ) bis(terpyridine)-modified pillar[5]arene(electron acceptor) and triazole triphenylamine amyl cyanide(electron donor) has been designed and constructed.Through the comparison of diverse solvents and acceptors,the two conditions,i.e.,modification of pillar[5]arene to donor and weak polar solvent are benefit for the occurrence of "efficient PET" because of shorter D-A distance in the presence of pillar[5]arene.Crucially,the fluorescence and PET process of the supramolecular assembly could be further modulated by solvent conversion and another competitive guest.The study provides a supramolecular method to design and construct tunable PET systems and PET-based smart materials.