An integrated supramolecular fungicide nanoplatform based on pH-sensitive metal–organic frameworks

The construction of an integrated nanoplatform with controlled fungicide delivery features in the specific microenvironment produced by fungal pathogens is a highly desirable strategy to improve the utilization of fungicides. Herein, we report a supramolecular fungicide delivery system based on benzimidazolemodified NH_(2)-MIL-101(Fe) metal–organic frameworks(B-MIL-101(Fe) MOFs) as carriers loaded with osthole(OS), and β-cyclodextrin(β-CD) as nanovalves to form β-CD@B-MIL-101(Fe)-OS. The nanoplatform can release the loaded OS for fungus control through self-degradation of the MOFs skeleton in an oxalic acid microenvironment produced by Botrytis cinerea. The experimental results exhibit that the constructed supramolecular fungicide delivery system could effectively inhibit mycelial growth and protect the tomatoes from infection by B. cinerea during the ripening stage. This strategy constructs a facile and integrated supramolecular drug delivery system for B. cinerea control and opens up a new avenue for the sustainable development of modern agriculture.

Smart phosphorescence from solid to water through progressive assembly strategy based on dual phosphorescent sources

Developing smart room-temperature phosphorescence(RTP)materials with facile and efficient strategies have attracted increasing attention.Herein,tunable RTP materials with two phosphorescent sources and stepwise enhanced phosphorescence in water are obtained through an in-situ self-assembly strategy based on the sensitization of phosphors by trimesic acid(TMA)through simple doping and the rigidification of phosphors by hydrogen-bonded organic frameworks(HOFs).As expected,doped TMA+phosphors simultaneously promote the RTP emission of phosphors and maintain TMA phosphorescence.In-situ assembled HOF(MATMA)@phosphors facilitate smart RTP emission in water due to the coexistence of phosphorescent HOF(MA-TMA)host and phosphors guest.Additionally,such RTP materials with good processability demonstrate the application potential in information security,benefitting from their varied afterglow lifetimes and easy luminous recognition in the darkness.This work will inspire the design of dual phosphorescent source RTP systems and provide new strategies for the development of smart RTP materials in water.

Stimuli-responsive fluorescent supramolecular polymer network based on a monofunctionalized leaning tower[6]arene

A fluorescent supramolecular polymer network with an excellent triple-stimuli responsive property based on metal-ligand coordination and host-guest interactions has been constructed from a terpyridine-monofunctionalized leaning tower[6]arene,a tetraphenylethylene AIEgen,and a bridging coordination ion(Zn^2+).Addition of competitive binding agents,trifluoroacetic acid,and/or pillar[5]arene can break the metal coordination and/or host-guest inclusion complexation,and thermal heating can weaken the non-covalent interactions in the supramolecular polymer gel,all leading to the gel-to-sol transition.

Gold nanoparticles functionalized with supramolecular macrocycles

Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins （CDs）, cucurbit[n]urils （CB[n]）, calix[n]arenes, and pillar[n]arenes （PIn]A）. Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.

Applications of covalent organic frameworks(COFs)：From gas storage and separation to drug delivery

Covalent organic frameworks（COFs） are an emerging class of porous covalent organic structures whose backbones were composed of light elements（B,C,N,O,Si） and linked by robust covalent bonds to endow such material with desirable properties,i.e.,inherent porosity,well-defined pore aperture,ordered channel structure,large surface area,high stability,and multi-dimension.As expected,the abovementioned properties of COFs broaden the applications of this class of materials in various fields such as gas storage and separation,catalysis,optoelectronics,sensing,small molecules adsorption,and drug delivery.In this review,we outlined the synthesis of COFs and highlighted their applications ranging from the initial gas storage and separation to drug delivery.

Controlled drug delivery systems based on calixarenes

In recent years, cancer has become the number two cause of death around the world, and scientists have exploited various treatment maps. Calixarenes, with diversified features, have been widely applied into drug delivery systems, which can respond to multi-stimuli and exhibit excellent performance. In this mini-review, we summarize the recent advances on controlled drug delivery systems based on calixarenes, in the form of inclusion complexes, amphiphilic self-assembly nanocarriers including micelles, hydrogels, vesicles and liposomes, and supramolecular nanovalves on mesoporous silica nanomaterials.

Electrochemical determination of paraquat using a glassy carbon electrode decorated with pillararene-coated nitrogen-doped carbon dots

An electrochemical sensor(carboxylatopillar[5]arene-coated nitrogen-doped carbon dots,namely CCDs)based on carboxylatopillar[5]arene(CP[5])functionalized nitrogen-doped carbon dots(N-CDs)has been developed in a facile and economic manner.To improve the performance of this electrochemical sensor in pesticide detection,the optimal solution pH(pH 7)and loading amount of CCDs on the electrode(0.50 mg/mL)have been determined.By virtue of the good conductivity of N-CDs and the molecular recognition property of CP[5],CCDs modified glassy carbon electrode,namely CCDs/GCE,shows excellent anti-interference capability,selectivity,stability,and reproducibility in the sensitive detection of paraquat.The peak currents are proportional to the paraquat concentration(from 0.1μmol/L to 10μmol/L)with a detection limit of 6.4 nmol/L(S/N=3),indicating a great potential in pesticide detection.In comparison with the electrochemical sensors that require expensive metal nanoparticles and complex preparation processes,CCDs/GCE exhibits excellent detection capability of paraquat with lower cost and simpler preparation processes.

Temperature-sensitive polypeptide brushes-coated mesoporous silica nanoparticles for dual-responsive drug release

A biopolymer-inorganic hybrid system(MSN@PBLGF) is designed and fabricated from mesoporous silica nanoparticles(MSNs) and folic acid(FA)-terminated temperature-sensitive synthetic polypeptide,i.e.,poly(γ-benzyl-L-glutamate)(PBLG) derivative,through a thiol-disulfide exchange reaction,where MSNs with high drug loading capacity serve as drug nanocarriers and the biocompatible PBLG biopolymer brushes installed on MSN surface through disulfide bonds endow the system with tumor-specific recognition ability and GSH/temperature dual-stimuli responsiveness.Controlled drug release experiments indicate that DOX can be tightly hosted in the system with limited premature release,but efficiently released in response to an increased concentration of GSH and/or an elevated temperature.Intracellular experiments demonstrate that the DOX-loaded MSN@PBLGF nanohybrid shows outstanding cellular uptake and cell-growth inhibition effects on human lung cancer cell line A549 in comparison with healthy human cells such as hepatocyte cells LO2.

A Binary Supramolecular Assembly with Intense Fluorescence Emission, High pH Stability, and Cation Selectivity: Supramolecular Assembly-Induced Emission Materials

We construct a fuorescent supramolecular system(TPE-Q_(4)⊂DSP5)of excellent tolerance to a wide range of pH by the facile selfassembly of a new pillar[5]arene bearing disulfonated arms(DSP5)with an AIE-active tetraphenylethene-based tetratopic guest bearing four quaternary ammonium binding sites(TPE-Q_(4)),which exhibits strong blue emission even in dilute aqueous solutions along with much higher quantum yield and longer fuorescence lifetime than TPE-Q_(4) itself.Tis appreciable property can be attributed to the supramolecular assembly-induced emission(SAIE)mechanism endowed by the host-guest inclusion complexation based on synthetic macrocycles.Remarkably,the enhanced fuorescence of the supramolecular assembly is quenched efciently and exclusively by ferric ions in water with a high Stern–Volmer formula constant of 1.3×10^(5) mol^(−1),demonstrating the excellent cation selectivity and visualized responsiveness in ion sensing and detection.

Aggregation-induced emission systems involving supramolecular assembly

Aggregation-induced emission(AIE),as an exciting photophysical phenomenon,has been regarded as one frontier research topic within both ranges of molecular luminescence and materials science over the last two decades.Since controllable molecular ensembles with particular morphologies and tunable functions can be elegantly constructed in the realm of supramolecular chemistry,the integration of supramolecular assembly and AIE systems can expectedly bring about luminescent materials with tunable emission and tailorable well-ordered architectures.In this review,we will provide a summary of the creation and working mechanisms of AIE systems involving supramolecular systems that are driven by different supramolecular driving forces including hydrogen bonding,host−guest interactions,metal coordination,and π-π interactions.The morphological and photoluminescent features of these AIE-active supramolecular assemblies will be elucidated,and the regulated fluorescence properties of the AIEgens induced by the assembling-disassembling processes will be discussed in detail.

Molecular-scale drug delivery systems loaded with oxaliplatin for supramolecular chemotherapy

Smart strategies that can decrease the side effect and enhance the therapeutic efficacy of chemotherapy are in urgent need to meet the special demands of cance r therapy.Herein,two wate r-soluble macrocyclic hosts,i.e.,a carboxylated leaning tower[6]arene(CLT6) and a carboxylated [2]biphenyl-extended pillar[6]arene(CBpP6),are used to load chemotherapy drug oxaliplatin(OxPt) by forming inclusion complexes(OxPtСCLT6 and OxPtСCBpP6) through host-guest interactions.Interestingly,OxPt can be released from the macrocyclic cavities of these drug delivery systems(DDSs) via the competitive binding effect of spermine(SPM) because of the stronger binding abilities of CLT6/CBpP6 toward SPM as compared with OxPt,leading to enhanced cytotoxicity on SPM-overexpressed cancer cells,such as breast cancer MCF-7 cells.Moreover,compared to free OxPt,due to the low concentration of SPM in normal cells,OxPtСCGT6 and OxPtСCBpP6 demonstrated a decreased cytotoxicity on liver L02 cells,which is beneficial fo r reducing the side effect of anticancer drug during chemotherapy.Such a strategy might be extended to other antitumor drugs and water-soluble macrocycles with suitable cavity sizes to achieve controllable drug delivery and enhanced anticancer ability in supramolecular chemotherapy.

Carboxylatopillarene-Modified Reduced Graphene Oxides with High Water Dispersibility for Fluorescent Dye Sensing

Carboxylated pillar[5]arene(CP5)macrocycles were modified onto the surface of reduced graphene oxide(RGO)via covalent bonds to form new pillarene-functionalized RGO nanosheets,i.e.,RGO-CP5.The obtained RGO-CP5 nanosheets capable of molecular recognition exhibited much better water-dispersibility and enhanced fluorescence-quenching property as compared with native RGO.This new sensing platform holds great potentials in the sensing and detection of analytes,such as organic dye molecules and pesticides,in aqueous solutions.

Special Issue of“Pillararenes”

Organic supramolecular chemistry based on syn-thetic macrocycles has been playing a crucial role in chemistry,biology,materials science,and environ-mental science.As a rapid developing class of syn-thetic macrocycles with intrinsic characteristics and excellent properties first discovered in 2008,pil-lararenes(or pillarenes)have become more and more attractive on account of their unique features and great potentials in fabricating functional materials and devices.The past seven years have witnessed the innovative efforts of Chinese supramolecular chem-ists in developing and revolutionizing pillararene chemistry,and in particular,in seeking the real appli-cations of pillararenes in many research disciplines.

High-Performance n-Hexane Purification by Nonporous Adaptive Crystals of Leaning Pillar[6]arene

The production of high-purity n-hexane under mild conditions is of great significance in both the petrochemical industry and synthetic chemistry.Here,we report an easy-to-operate and energy-efficient n-hexane purification strategy using nonporous adaptive crystals of perethylated leaning pillar[6]arene(EtLP6).Adaptive EtLP6 crystals preferentially absorb n-hexane over other branched or cyclic C6 alkanes with similar boiling points.This selectivity arises from the different thermodynamic stabilities and variabilities of EtLP6 crystalloids loaded with n-hexane and other C6 alkanes.Moreover,the reversible transformations between the nonporous guest-free and n-hexane-containing structures make the EtLP6 crystals highly recyclable.

Functional Materials with Pillarene Struts

Pillar[n]arenes(pillarenes for short)are a relatively new generation of macrocyclic host compounds with rigid cylinder architectures containing several hydroquinone units that are bridged by methylene(−CH2−)at their para positions.The investigation of pillarenes has expanded from the sole domain of supramolecular chemistry to invoke immense interest among scientists striving to exploit intelligent materials or functional systems,with regard to their fascinating attributes such as symmetric structures,tailorable functionalization,and unique host−guest properties.Over the past few years,researchers have focused on the construction of prominent supramolecular architectures such as supramolecular switches,supramolecular polymers,and self-assembled amphiphilic systems on the basis of host−guest chemistry in collaboration with other noncovalent interactions.One of the most attractive characteristics of these supramolecular assemblies relies on the tunable mechanical motions via switching of the most conformationally and thermally stable structures in a dynamic and reversible manner,which could be affected by the external conditions and enable the reciprocal effect with surrounding environments.Consequently,macrocyclic arenes are the key components of stimuli-responsive supramolecular assemblies,serving as important candidates in the construction of advanced supramolecular materials,including organic functional systems and organic−inorganic hybrid systems.In this Account,we present a relatively elaborate summary of the significant and typical intelligent systems containing pillarenes and their extended versions with a focus on our own contributions to this field during the past decade.Finally,in the last section of the review,challenges and perspectives are given.