Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Several novel macrocyclic arenes that are composed of six indole subunits,so-called bisindole[3]arenes(BID[3]s),were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole derivatives and paraformaldehyde in dichloromethane at room temperature.Their macrocyclic structures were demonstrated by X-ray single-crystal studies,and the presence of the macrocyclic cavities made it possible to accommodate specific small organic molecules.The BID[3]s have exceptionally high iodine adsorption ability due to the strong and synergic interaction of indole units toward iodine,exhibiting significant morphology changes upon adsorption and desorption of iodine.Iodine uptake capacity of up to 5.12 g·g^(−1) was found with MeBID[3],which is the highest value ever reported for macrocyclic arenes.

Insertion of pillar[5]arene into Troger’s base-derived porous organic polymer for promoted heterogeneous catalytic performance in Knoevenagel condensation and CO_(2)fixation

Development of new metal-free heterogeneous catalysts has long been the focus of intense research interest.The integration of multifunctional monomers into the skeletons of porous organic polymers(POPs)provides an efficient pathway to achieve this goal.Herein,we rationally designed and successfully prepared a new Troger’s base(TB)-derived POPs by insertion of pillar[5]arene macrocycle as a positively auxiliary group.Combined the both merits of pillar[5]arene macrocycle and TB moiety,the as-prepared polymer was further explored as an effective metal-free heterogeneous catalyst and exhibited promoted catalytic performance in Knoevenagel condensation and CO_(2)conversion.This work provides a new strategy to fabricate metal-free heterogeneous catalysts based on macrocyclic POPs.

Hexnut[12]arene and its derivatives: Synthesis, host-guest properties, and application as nonporous adaptive crystals

Hexnut[12]arene(HN[12])and its derivatives,a new class of sixfold macrocyclic arenes,were designed and synthesized in reasonable yield by a one-pot reaction at room temperature using dimethoxymethane as a methylene source.HN[12],which bears a large,symmetric,and rigid cavity,was easily functionalized at both the methylene bridges and the hydroquinone units.A water-soluble fluorescent HN[12]was synthesized and used as a host to encapsulate benzyl viologen dichloride in water with a high binding affinity of(3.4±0.2)×10^(6)M^(-1).The nonporous adaptive crystal(NAC)of HN[12]was found to capture not only inorganic molecules(iodine)but also trace amounts of large organic molecules(basic fuchsine)from water,which greatly expands the scope of NACs for adsorption.

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.

Prospering the biphen[n]arenes family by tailoring reaction modules

Reported here is the comprehensive investigation on the formation of biphen[n]arenes by tailoring reac-tion modules.Five new macrocyclic arenes and four oligomers were synthesized by the condensation of monomers possessing different multimethoxyphenyl reaction modules and paraformaldehyde.We proved that the number and sites of methoxy on reaction modules greatly affected the reaction activity,shape,and connection mode of macrocycles.Moreover,the triangular and saddle-shaped configuration of macro-cycles were revealed by single crystal structures.The results provided a typical and fundamental guidance in designing new macrocyclic arenes.