High adsorption and separation performance of CO_(2) over N2 in azo-based(N=N)pillar[6]arene supramolecular organic frameworks

Azo-based pillar[6]arene supramolecular organic frameworks are reported for CO_(2) and N_(2) adsorption and separation by density functional theory and grand canonical Monte–Carlo simulation.Azo-based pillar[6]arene provides suitable environment for CO_(2) adsorption and selectivity.The adsorption and selectivity results show that introducing azo groups can effectively improve CO_(2) adsorption and selectivity over N_(2),and both CO_(2) adsorption and CO_(2) selectivity over N_(2) follow the sequence pillar[6]arene N_(4)>pillar[6]arene N2>pillar[6]arene.Pillar[6]arene N_(4) exhibits CO_(2) adsorption capacity of1.36 mmol/g,and superior selectivity of CO_(2) over N_(2) of116.75 with equal molar fraction at 1 bar(1 bar=105 Pa)and 298 K.Interaction analysis confirms that both the Coulomb and van derWaals interactions between CO_(2) with pillar[6]arene frameworks are greater than that of N_(2).The stronger affinity of CO_(2) with pillar[6]arene N_(4) than other structures and the larger isosteric heat differences between CO_(2) and N2 rendered pillar[6]arene N4 to present the high CO_(2) adsorption capacity and high CO_(2) selectivity over N_(2).Our results highlight the potential of azo-functionalization as an excellent means to improve pillar[6]arene for CO_(2) capture and separation.

A stable metal-covalent-supramolecular organic framework hybrid: enrichment of catalysts for visible light-induced hydrogen production

Cubic metal-covalent-supramolecular organic framework(MCSOF-1)hybrid has been created from the reaction of two molecular components and subsequent co-assembly with cucurbit[8]uril(CB[8])in water.In the presence of CB[8],[Ru(bpy)_3]^(2+)-based acylhydrazine 1·2Cl reacted with aldehyde 2·Cl to quantitatively yield six-armed precursor 3·8Cl through the generation of MCSOF-1.MCSOF-1 combines the structural features of metal-,covalent-and supramolecular organic frameworks.Its periodicity in water and in the solid state was confirmed by synchrotron X-ray scattering and diffraction experiments.MCSOF-1could enrich discrete anionic polyoxometalates(POMs),maintain periodicity in acidic medium,and remarkably facilitate visible light-induced electron transfer from its[Ru(bpy)_3]^(2+)units to enriched POMs,leading to enhanced catalysis of the POMs for the reduction of proton to H_2in both aqueous(homogeneous)and organic(heterogeneous)media.

Loading-free supramolecular organic framework drug delivery systems(sof-DDSs) for doxorubicin:normal plasm and multidrug resistant cancer cell-adaptive delivery and release

Four water-soluble porous supramolecular organic framework drug delivery systems（sof-DDSs） have been used to adsorb doxorubicin（DOX） in water at physiological pH of 7.4,which is driven exclusively by hydrophobicity.The resulting complexes DOX@SOFs are formed instantaneously upon dissolving the components in water.The drug-adsorbed sof-DDSs can undergo plasm circulation with important maintenance of the drug and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells.DOX is released readily in the cancer cells due to the protonation of its amino group in the acidic medium of cancer cells.In vitro and in vivo experiments reveal that the delivery of SOF-a-d remarkably improve the cytotoxicity of DOX for the MCF-7/Adr cells and tumors,leading to 13-19-fold reduction of the 1C_（50）values as compared with that of DOX.This new sof-DDSs strategy omits the indispensable loading process required by most of reported nano-scaled carriers for neutral hydrophobic chemotherapeutic agents,and thus should be highly valuable for future development of low-cost delivery systems.

In situ-prepared homogeneous supramolecular organic framework drug delivery systems(sof-DDSs)：Overcoming cancer multidrug resistance and controlled release

Water-soluble three-dimensional porous supramolecular organic frameworks（SOFs） have been demonstrated as a new generation of homogeneous polycationic platforms for anti-cancer drug delivery.The new SOF drug delivery systems（sof-DDSs） can adsorb dianionic pemetrexed（PMX）,a clinically used chemotherapeutic agent instantaneously upon dissolving in water,which is driven by both electrostatic attraction and hydrophobicity.The in situ-prepared PMX@SOFs are highly stable and can avoid important release of the drug during plasm circulation and overcome the multidrug resistance of human breast MCF-7/Adr cancer cells to enter the cancer cells.Acidic microenvironment of cancer cells promotes the release of the drug in cancer cells.Both in vitro and in vivo studies have revealed that sofDDSs considerably improve the treatment efficacy of PMX,leading to 6-12-fold reduction of the IC50 values,as compared with that of PMX alone.The new drug delivery strategy omits the loading process required by most of reported nanoparticle-based delivery systems and thus holds promise for future development of low-cost drug delivery systems

[5]Rotaxane, linear polymer and supramolecular organic framework constructed by nor-seco-cucurbit[10]uril-based ternary complexation

Here we use nor-seco-cucurbit[10]uril(ns-CB[10]) based ternary complexation to construct [5]rotaxane,linear supramolecular dynamic rotaxane polymers and cubic 3D supramolecular organic framework.A [5]rotaxane is constructed by ns-CB[10], TMe CB[6] and short linear derivatives of 4,4'-bipyridinium(M2). ns-CB[10], CB[7] and long linear derivatives of 4,4'-bipyridinium(M3) self-assemble into a linear supramolecular dynamic rotaxane polymer. ns-CB[10] and tetracationic tetrahedral monomer selfassemble and form a three-dimensional supramolecular organic framework. The above results demonstrate that ns-CB[10]-based ternary complexation is a versatile platform to build various supramolecular systems.

Successive construction of cucurbit[8]uril-based covalent organic frameworks from a supramolecular organic framework through photochemical reactions in water

Functional framework materials have been developed for many applications including adsorption, asymmetric catalysis, sensing,drug delivery, optical device, and so on. Here, we report the successive construction of two cucurbit[8]uril-based covalent organic frameworks(COFs) including tetraphenylethene-based COF(COF-1) and phenanthrene-based COF(COF-2) from a two-dimensional(2D) periodic cucurbit[8]uril-based supramolecular organic framework(SOF-1) as the prearranged structure via the intermolecular photocycloaddition of the coumarin units and the intramolecular photocyclization of the tetraphenylethene(TPE) units under ultraviolet(UV) irradiation(365 nm) in water. In this case, oxygen(O_(2)) plays an important role in the photocyclization of the TPE units into the phenanthrene units in the transform process from SOF-1 or COF-1 to COF-2. As the TPE units further form phenanthrenes after UV-irradiation, COF-2 exhibits aggregation-caused quenching effect and weak green emission, while COF-1 displays a strong yellow emission due to the aggregation-induced emission. Besides, the adaptive chirality of cationic COF-1 as a biomolecular sensor can be efficiently induced by chiral anionic biomolecules including adenosine-5′-triphosphate(ATP) and adenosine-5′-diphosphate(ADP) to exhibit sensitive negative circular dichroism responses in water. This supramolecular approach to construct COF from SOF via photochemical reactions may open a new opportunity for the construction and application of the water-soluble COFs with well structural controllability, unique photophysical properties,and favorable biocompatibility.

Toward a Two-Dimensional Supramolecular Organic Framework with High Degree of Internal Order via Amphiphilic Modification

Solution-phase self-assembly of two-dimensional(2D)networks with a high degree of internal order and long-range periodicity is a great challenge.Herein,we report a rational design to improve 2D self-assembly in water through amphiphilic modification of the building block.An amphiphilic tritopic molecule(1)is designed and synthesized by introducing three hydrophilic oligo(ethylene glycol)moieties and three hydrophobic hexyl chains.The assembly of 1 and cucurbit[8]uril(CB[8])leads to the formation of a Janus 2D supramolecular organic framework(SOF),which further creates unique bilayer supramolecular networks and exhibits an unprecedentedly high degree of internal order and long-range periodicity.In contrast,the assembly of a nonamphiphilic analog(2)with CB[8]only generates a 2D SOF with a lower degree of internal order,suggesting that the inherent amphiphilicity of 1 plays a crucial role in improving its 2D self-assembly in aqueous phase.

Dimension-Controllable and Photo-Responsive Supramolecular Organic Framworks through Cucurbit[8]uril-based Self-Assembly

Dimension-controllable supramolecular organic frameworks(SOFs)with aggregation-enhanced fluorescence are hierarchically fabricated through the host-guest interactions of cucurbit[8]uril(CB[8])and coumarin-modified tetraphenylethylene derivatives(TPEC).The three-dimensional layered SOFs could be constructed from the further stacking of two-dimensional mono-layered structures via simply regulating the self-assembly conditions including the culturing time and concentration.Upon light irradiation under the wavelength of 365 nm,the photodimerization of coumarin moieties occurred,which resulted in the transformation of the resultant TPECn/CB[8]4n two-dimensional SOFs into robust covalently-connected 2D polymers with molecular thickness.Interestingly,the supramolecular system of TPEC/CB[8]exhibited intriguing multicolor fluorescence emission from yellow to blue in the time range of 0-24 h at 365 nm irradiation,possessing potential applicability for photochromic fluorescence ink.

Chiral supramolecular 2D halogen-bonded organic frameworks constructed by post-synthetic modified cross-linking strategy

The development of preparation methods for XOFs,as a new class of organic frameworks,plays a crucial role in shaping their structures,functions,and potential applications.In this study,we presented the construction of chiral supramolecular 2D halogen-bonded organic frameworks(XOFs)through a post-synthetic modification strategy.A linear halogen-bonded organic polymer(XOP),XOP-DPBA,decorated with aldehyde groups,was initially prepared to validate the feasibility of post-synthetic modification for XOF construction and functionalization.XOP-DPBA exhibited excellent reactivity with amines,forming imine bonds.By utilizing this reactivity,a series of cross-linked 2D XOFs were efficiently prepared through post-synthetic modified cross-linking reactions.Furthermore,we successfully introduced chiralα/β-cyclodextrins(α/β-CD)into the XOF skeletons via host-guest interactions,resulting in the fabrication of chiral supramolecular 2D XOFs.These chiral XOFs displayed the induced circular dichroism(ICD)signals and assembled them into helical fibers.The post-synthetic modification strategy demonstrated its versatility and simplicity for the construction and functionalization of XOFs.

Viologen derivatives with extendedπ-conjugation structures:From supra-/molecular building blocks to organic porous materials

Recently,increasing atte ntion has been paid on extending theπ-conjugation structures ofviologens(1,1’-disubstituted-4,4’-bipyridylium salts)by incorporating planar aromatic units into the bipyridinium backbones.Various viologen derivative s with extendedπ-conjugation structures have been synthesized,including the N-termini aromatic substituted viologens,the extendedπ-conjugated viologens(denoted as ECVs)as well as theπ-conjugated oligomeric viologens(denoted as COVs).These compounds typically exhibit interesting properties distinguished from those of an isolated viologen unit,which make them as new class of electron deficient supra-/molecular building blocks in supramolecular chemistry and materials science.In this review,we would like to highlight the recent advances of viologen derivatives with extendedπ-conjugation structures in versatile applications ranging from electrochromic and energy storage materials,the ECV/COV-based supramolecular self-assembly systems including the linear supramolecular polymers and 2D/3D supramolecular organic frameworks(SOFs),to the viologen-based covalent organic frameworks(COFs)/networks.We hope this review will serve as an in-time summary worthy of referring,more importantly,to provide inspiration in the rational design of novel molecules with unexplored properties and functions.

A self-assembled framework that interpenetrates in crystal but does not interpenetrate in solution

A porous supramolecular framework has been for the first time revealed to undergo interpenetration in crystal and noninterpenetration in solution.A new supramolecular organic framework Bu-SOF has been constructed from the co-assembly of a tetracationic tetrahedral monomer and cucurbit[8]uril(CB[8])in water through the encapsulation of two anti-parallel n-butyl chains by CB[8].X-ray diffraction analysis reveals that Bu-SOF forms 3-fold interpenetrated networks in crystals grown by evaporation of its solution in water.1 H NMR,dynamic light scattering and isothermal titration calorimetric experiments confirm that Bu-SOF is also formed in water.Solid samples,prepared by lyophilizing the aqueous solution of Bu-SOF,can adsorb nanoscaled organic dyes,supporting the porosity of the framework and thus non-interpenetration in solution.The avoidance of interpenetration of Bu-SOF in solution has been attributed to the filling of water inside the porous framework as well as the electrostatic repulsion of the appended bipyridinium units of the tetrahedral building block.

光响应有机模块自组装导致的氧自由基转化及其光催化应用

在光催化反应中实现对活性氧物种的单线态氧和超氧阴离子自由基的有效控制仍然是一个巨大挑战.本工作报道了一个从光敏模块构筑主客体超分子有机框架(SOF)策略,有效地实现了单线态氧到超氧阴离子自由基的转化.该TPA-BP-SOF结构中的光敏模块由四个4,4′-联吡啶盐(BP)单元修饰的苯基桥接双(三苯胺)衍生物(TPA-BP)构成.来自于不同的TPA-BP中的两个BP单元通过与葫芦[8]脲(CB[8])发生首尾相连的强络合作用,形成了具有周期性孔结构和均匀溶解度的二维超分子有机框架纳米片结构.与单体TPA-BP中检测到的生成单线态氧的能量转移机制不同,通过主客体相互作用形成的TPA-BP-SOF能够有效促进电子转移高效产生超氧阴离子自由基.同时,该TPA-BP-SOF生成的超氧阴离子自由基能有效地用于水相芳基硼酸的氧化羟基化和N-苯基四氢异喹啉的氧化,收率分别高达88%和83%.本研究提出了一种利用SOF实现II型光敏剂向I型光敏剂有效转化的新方法,成功展示了其在光催化有机转化中的实际应用.