Photoactive donor-acceptor conjugated macrocycles:New opportunities for supramolecular chemistry

The design and synthesis of photoactive macrocyclic molecules continue to attract attention because such species play important roles in supramolecular chemistry as well as photoelectronic applications.Donoracceptor(D-A)conjugated macrocycles are an emerging class of photoactive molecules due to their D-A conjugated structural characteristics and tunable optical properties.In addition,the well-defined cavities in such D-A macrocycles endow them with versatile host-guest properties.In this review,we provide a comprehensive summary of D-A conjugated macrocycle chemistry,detailing recent progress in the area of synthetic methods,optical properties,host-guest chemistry and applications of the underlying chemistry to chemical sensors,bioimaging and photoelectronic devices.Our objective is to provide not only a review of the fundamental findings,but also to outline future research directions where D-A conjugated macrocycles and their constructs may have a role to play.

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

Metal–metal cooperativity effects have been extensively explored in olefin polymerization,along with the design and preparation of many binuclear transition metal catalysts.However,their synthesis and the tuning of metal–metal distance are complicated and time-consuming.In this contribution,a supramolecular chemistry strategy was used to construct multinuclear olefin polymerization catalysts.Urea functional groups were installed into severalα-diimine palladium catalysts to enable hydrogenbonding-induced self-assembly.

Cellulose-based hydrogels regulated by supramolecular chemistry

Supramolecular hydrogels based on cellulose attract increasing attention because of their novel structures and broad potential applications.In this review,hydrogels composed of cellulose are summarized according to category of supramolecular interactions in the networks including hydrogen bonds,electrostatic interactions,host-guest interactions,and others.Supramolecular cellulose-based hydrogels constructed by noncovalent bonding usually exhibit environmental friendliness,designing flexibility and diverse functions,and their properties are variable with incorporating different interactions in hydrogel networks.Moreover,with proper structures and networks,the supramolecular cellulose-based hydrogels are adaptable in diverse fields of research and practical applications,such as self-healing,shape memory,drug delivery,and some other renewable/sustainable materials.The future developments and challenges of the supramolecular hydrogels based on cellulose are discussed as well.

Supramolecular flow chemistry: Construction of multiscale supramolecular assemblies by micro/nanofluidic techniques

The rapid and precise fabrication of multiscale supramolecular assemblies using micro/nanofluidic techniques has emerged as a dynamic area of research in supramolecular chemistry, materials chemistry, and organic chemistry. This review summarizes the application of micro/nanofluidic techniques in constructing supramolecular assemblies, including nanoscale supramolecular assemblies such as macrocycles and cages, microscale supramolecular assemblies such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs), and macroscale supramolecular assemblies such as supramolecular hydrogels. Compared to conventional synthesis methods, micro/nanofluidic techniques for the production of supramolecular assemblies have significant advantages, including enhanced safety, high reaction rates, improved selectivity/yield, and scalability. Additionally, micro/nanofluidic systems facilitate the creation of precisely controllable micro/nanoconfined environments, allowing for a unique flow behavior that improves our understanding of the supramolecular self-assembly process. Such systems may also lead to the development of novel supramolecular assemblies that differ from those generated via traditional methods.

Syntheses and Crystal Structures of Two New Supramolecular Architectures Constructed from the Main Group Metal Chloride and Protonated 2-(3-Pyridyl)benzimidazole

The reactions of SbCl3 and HgCl2 with 2-（3-pyridyl）benzimidazole （PyBIm） in solution acidified with HCl have been investigated. The PyBIm ligands are protonated into 2-（3-pyridinio）benzimidazolium （H2PyBIm） cations and the corresponding metal ions are bonded with chloride atoms into coordination anions, forming two new coordination compounds, namely, （H2PyBIm）（SbCl5） 1 and （H2PyBIm）2（Hg2Cl8） 2. Both compounds were characterized by X-ray crystallography. Crystal data for 1： triclinic, space group P1^- with a = 5.7030（7）, b = 9.0625（11）, c = 16.5929（18） A, α = 91.808（7）°, β = 93.234（6）, γ = 99.216（7）°, C12H11N3SbCl5, Mr = 496.24, V = 844.44（17） A^3, Z = 2, Dc = 1.952 g/cm^3, μ（MoKα） = 2.419 mm^-1, F（000） = 480, the final R = 0.0496 and wR = 0.1382 for 3433 observed reflections （I 〉 2σ（I））. Crystal data for 2： monoclinic, space group P21/c with a = 7.8061（5）, b = 15.8127（9）, c = 12.2435（9） , β = 91.955（4）o, C24H22N6Hg2Cl8, Mr = 1079.26, V = 1510.40（17） 3, Z = 2, Dc = 2.373 g/cm3, μ（MoKα） = 10.889 mm-1, F（000） = 1008, the final R = 0.0293 and wR = 0.0562 for 2854 observed reflections （I 〉 2σ（I））. X-ray diffraction analysis reveals that the antimony（III） is five-coordinated, exhibiting a slightly distorted square-pyramidal coordination geometry; while in 2, a dimeric [Hg2Cl8]^4-anion consists of two trigonal bipyramids sharing two common edges. The organic cations and coordination anions are connected into a one-dimensional belt and a two-dimensional sheet through N-H···Cl hydrogen bonding interactions in compounds 1 and 2, respectively; both are further aggregated into 3D frameworks by strong π-π contacts.

Gear-like array of (H_2O)_(12) as building blocks in one-dimensional supramolecular assembly

The preparation and crystal structure of complex Co（Hsae）2·2H2O （1, H2sae = N-salicylidene-2-iminoethanol） are reported. X- ray analysis revealed that every six Co（Hsae）2 forms a cyclic chip and every 12 water forms a novel gear-like cluster. Acting as building blocks, the gear-like water cluster and complex chip are connected in A-B fashion and extend into one-dimensional supramolecular chain. Hydrogen bond is the primary bridging force in the formation of supramolecular framework.

Supramolecular Self-assembly and Functionalization of Porphyrin-based Systems

Porphyrins are abundant in nature. They have been frequently employed as building blocks in the construction of nanoarchitectures and functional supramolecular systems. Recently, a series of novel porphyrin molecules including small molecules and polymers have been originally designed and synthesized with the aim of producing nanostructures with controllable-growth and materials with high-performance. Literature coverage is through 2004-2012. This review gives a full summary of related studies in our group.

A Novel Layered Supramolecular Network Constructed from Heterohexanuclear La(Ⅲ)-Cr(Ⅲ) Complexes by Hydrogen Bonding

The complex [La2(m-ox){Cr(bipy)(m-ox)(ox)}4(H2O)6]?2.3(H2O) (C58H68.6N8O54.3Cr4La2) 1 has been obtained from the reaction of La(Ⅲ) salt with [Cr(bipy)(ox)2]- (bipy = 2,2?bipyridine and ox = oxalate dianion) building blocks in aqueous solution and structurally characterized by X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/c with a = 10.740(2), b = 17.943(4), c = 22.388(5) ? V = 4314(2) 3, Z = 2, Mr = 2232.43, Dc = 1.719 g/cm3, F(000) = 2234, m(MoKa) = 1.565 cm-1 and T = 293(2) K. With the use of 5202 observed reflections (I > 2s(I)), the structure was refined to R = 0.0742 and wR = 0.1554. Complex 1 shows a two-dimensional open network constructed from hexanuclear {La2Cr4} units through the intermolecular hydrogen interactions.

Supramolecular Architecture from the Self-assembly of One-dimensionalCoordination Polymers and Hydrogen Bonds

The novel one-dimensional coordination polymer {[Cu(L)2(H2O)]?2BF4?6H2O}∞ [1, L=1,2-bis(4-pyridinecarboxamido)ethane] was synthesized as single crystals and characterized by means of X-ray diffraction analysis, elemental analysis, IR spectroscopy and TG measurement. Structure 1 consists of looped chains. In addition, linked by hydrogen bonds, the one-dimensional chains were transformed into three-dimensional framework, which shows channels filled with anions and uncoordinated water molecules.

Polysaccharide based supramolecular injectable hydrogels for in situ treatment of bladder cancer

Implantable system maximizes drug concentration and continuously releases drugs near the tumor,which is an effective tool to solve the difficult retention of chemotherapy drugs in bladder cancer.In this work,a novel polysaccharide supramolecular injectable hydrogel(CCA hydrogels for short)is rapidly constructed by simply mixing cationic chitosan,anionic sulfobutyl etherβ-cyclodextrin(SBE-β-CD)and a trace amount of silver ions.The injected hydrogel reconstituted and regained its shape in less than 1 h,and it can still maintain the elasticity suitable for the human body.By packaging the drug directly,the gel achieves a high concentration of doxorubicin,an anticancer drug.Using MB49-luc cells as the model of bladder tumor for anti-tumor in vivo,the CCA-DOX gel has obvious inhibitory effect on bladder tumor,and its inhibitory effect is much greater than that of free DOX.Therefore,this self-healing injectable hydrogel has great potential for in situ treatment of bladder cancer.

Differentiated self-assembly through orthogonal noncovalent interactions towards the synthesis of two-dimensional woven supramolecular polymers

Molecular weaving is a powerful approach to make molecularly woven materials that have showed unprecedented characteristics and properties intrinsically distinct to those of non-woven materials.We here report a facile and efficient approach for the synthesis of 2D woven supramolecular polymers by differentiated self-assembly through orthogonal noncovalent interactions.Importantly,the difference in binding strength of two orthogonal noncovalent interactions can be used to control the process of molecular weaving.Consequently,single-layered 2D woven supramolecular polymers were synthesized and fully characterized by various techniques.This study demonstrates a controllable method for molecular weaving,and will significantly hasten the development of molecularly woven materials.

Stabilization and detection of labile reaction intermediates in supramolecular containers

Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways.However,most reactive intermediates are unstable and present at low concentrations;their short lifetimes make them difficult to detect and characterize.Supramolecular containers offer opportunities for the stabilization and characterization of those labile species,through isolation from the media and protection inside the cavity of the host.In this review,we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers.The container compounds include carcerands,deep cavitands and amide naphthotubes.We focus on unstable guest species-cyclobutadiene,benzocyclopropenone,o-benzyne,1,2,4,6-cycloheptatetraene,anti-Bredt's olefin,fluorophenoxycarbene,O-acylisoamide,and hemiaminalthat act as intermediates in certain organic reactions.

Supramolecular cyclization induced emission enhancement in a pillar[5]arene probe for discrimination of spermine

Early diagnosis and treatment of cancer requires the development of tools that are both sensitive and selective in detecting spermine.In this study,we presented a"supramolecular cyclization-induced emission enhancement"strategy for the sensitive and selective detection of spermine.A new pillar[5]arene probe(P1)demonstrated excellent solution/solid dual-state emission properties,and the addition of certain spermine(Spm)resulted in fluorescence enhancement due to the synergy of multiple weak interactions that restricted the free motion of P1 in the P1⊃Spm complex.This mechanism was further confirmed by time-resolved spectroscopy,DFT calculations,and IGM analysis.With its low limit of detection and high selectivity,P1 is a promising tool for measuring spermine in artificial urine samples.

Supramolecular Manipulation of Intracellular Acidic Vesicles to Improve Cellular Self-Repair and Self-Defense

Lysosomes are the“cell stomach”that digests various species including macromolecules and pathogens for self-repair and self-defense upon fusion with endosomes,autophagosomes,and phagosomes.Therefore,artificially manipulating intracellular vesicles could potentially promote lysosome-mediated intracellular digestion for disease prevention and treatment.Herein,a supramolecular strategy to efficiently tether and fuse acidic vesicles(i.e.,lysosomes,late endosomes,autolysosomes,and phagosomes)has been developed for the first time to enhance the digestion of cellular wastes and foreign matter,including pathogens.A linear polyethylene glycol(PEG)derivative dually tagged with morpholine(MOR)and adamantane(ADA)on the opposite side,namely,MOR-PEG-ADA,was designed to target intracellular acidic vesicles via MOR and to decorate their surfaces with ADA.Subsequently,the addition of cucurbit[7]uril(CB[7])grafted hyaluronic acid(HA)induced supramolecular tethering and fusion of acidic vesicles via strong host-guest interactions between CB[7]of CB[7]-HA and ADA residing on the surface of acidic vesicles.As a proof-ofconcept,the overall cellular metabolism,including endogenous autophagy and the exogenous endocytosis and phagocytosis,was effectively upregulated,demonstrating that supramolecular regulation of the dynamics of intracellular acidic vesicles may promote the lysosome’s digestion to significantly improve cellular self-repair and self-defense.

Supramolecular Thermally Activated Delayed Fluorescence Materials via Through-Space Charge Transfer

Thermally activated delayed fluorescence(TADF)polymeric materials based on through-space charge transfer(TSCT)have emerged as a highly studied topic in recent years.However,the construction of TSCT TADF materials via a supramolecular approach is still a big challenge.In this work,we report the noncovalent synthesis of TSCT TADF materials using a cyclic peptide-based bottle-brushed supramolecular polymer as a scaffold.By bringing the TSCT donor and acceptor in close proximity in space using the supramolecular scaffold,distinctive TADF emission in both solution and solid states could be achieved.Furthermore,the TADF system could be utilized as a sensitizer to coassemble with fluorescence acceptors to build thermally assisted fluorescence systems,resulting in color-tunable delayed fluorescence with high efficiency and color purity.Our findings provide a facile yet effective approach to designing and fabricating TSCT TADF materials,which might hold great potential for applications in the fields of organic light-emitting diode,bioimaging,and sensing.

Improvement of hybridization signals of gold label silver stain gene detection

The factors that influence the colorimetric gene detection of gold label silver stain and improve the detection signals were studied. The influence of amino DNA probes and thiol DNA modified gold nanoparticles was investigated based on a sandwich hybridization system. An increase in amino probe concentration brought about an increase in hybridization signal which reached a threshold corresponding to the saturated concentration of amino probes bounded onto a glass slide surface. Since the steric hindrance effect of nanoparticles was dominant over the influence of a surface area, the bigger gold nanoparticles led to weaker hybridization signals. The hybridization efficiency enhanced significantly with the increase of the thiol DNA modified nanoparticle concentrations. Experimental results showed that 125 μmol/L of the amino DNA probe concentration, 15 nm of the gold nanoparticle diameter, and 4.07 nmol/L of the thiol DNA modified gold nanoparticle concentration were optimal for the detection system. The hybridization signals can be improved remarkably by choosing optimal hybridization conditions.

A Colorimetric Receptor Based on SchiffoBase Bearing Azo-Phenolic Hydroxy Group

A novel N-（2-hydroxy-5-chlorodibenzophenone）-N＇-[2-hydroxy-5-azophenyl-benzaldehyde]- 1,2-diaminobenzene receptor has been synthesized by simple steps with good yields. The anion recognition properties were studied by ultraviolet-visible spectroscopy. The results showed that the receptor had a higher affinity to F-, AcO-, and H2PO4-, but no evident binding with Cl-, Br-, and l-. Upon addition of the three former anions to the receptors in DMSO, the solution exhibited an obvious color change from colorless to yellow, which could be observed by the naked eye, thus the receptor could act as a fluoride ion sensor even in the presence of other halide ions. The UV-Vis data indicates that a 1：1 stoichiometric complex is formed through hydrogen bonding interactions between receptor and anions.

The Paramagnetic 2D Chiral-porous Polymer of L-Phenylalanine and Manganese

Mn(L-Phe)2稨2O]n (Phe=phenylalanine) with a single stranded coordination poly- mer has been synthesized by self-assembly of manganese salt and phenylalanine and characterized by X-ray single-crystal diffraction method. The complex crystallizes in the orthorhombic, space group P212121 with a = 6.0911(1), b = 10.3642(1), c = 30.4321(7) ? V = 1921.16(6) ?, Z = 4, Dc = 1.387 g/cm3, C18H22N2O5Mn, Mr = 401.32, F(000) = 836 and m(MoKa) = 0.717 mm-1. The final R = 0.0614 and wR = 0.1412 for 2291 observed reflections with I > 2s(I). The magnetic behavior study shows that there exist super-exchange antiferromagnetic interactions between the magnetic centers through the effective exchange pathway of the carboxylate group.

Recent progress in supramolecular chiral photochemistry

Chiral photochemistry appears to be a highly challenging topic and still very much in its infancy, especially if comparing to its well-developed thermochemical counterpart.Significant efforts have been devoted in order to improve stereoselectivity of chiral photoreactions,among which,the supramolecular strategy proven the most promising.The present review,motivated by the rapid progress in the supramolecular chiral photochemistry,concentrates on advancements achieved mainly in the last decade.The features and advantages of supramolecular chiral photochemistry are exemplified by representative photoreactions in terms of the chiral hosts/assemblies.

Recent Progress in Constructing Structurally Ordered Polymeric Architectures via Dynamic Covalent Chemistry

Although dynamic covalent chemistry(DCvC)has been widely utilized to synthesize small molecules and polymers,it remains challenging to construct highly ordered polymeric architectures via DCvC.Further exploration of novel dynamic linkages(in addition to commonly used imine and boronate ester)will expand the library of readily accessible dynamic linkages,diversify the polymeric structures,and unlock new functionality.In this mini-review,the DCvC-based synthetic strategies for enhancing the structural orders of polymeric architectures will be discussed from both thermodynamic control and kinetic control aspects.The relationship between the structure,stability,and dynamic behavior of a DCvC bond will be presented.Then recent examples of constructing polymers with DCvC and supramolecular bonding interactions,such as metal-ligand coordination,host-guest binding,and hydrogen bonding,will be reviewed to demonstrate their synergistic relationship.Furthermore,polymers featuring relatively unexplored DCvC will be highlighted to underscore how developing novel dynamic linkages and fundamental DCvC studies can broaden the scope of functional polymeric architectures.In the end,the challenges in the current field and possible future directions will also be discussed.Advancements in using these design principles will undoubtedly lead to the development of intriguing chemistries,polymeric architectures,and functionality.