Non-statistical assembly of multicomponent [Pd2ABCD] cages

Self-assembled hosts, inspired by biological receptors and catalysts, show application potential in sustainable synthesis, energy conversion and medicine. Implementing multiple functionalities in the form of distinguishable building blocks, however, is difficult without risking narcissistic self-sorting or a statistical mess. Here we report a systematic series of integratively self-assembled heteroleptic cages in which two square-planar PdII cations are bridged by four different bis-pyridyl ligands, A, B, C and D, via synergistic effects to exclusively form a single isomer-the lantern-shaped cage [Pd2ABCD]. This self-sorting goal-forming just one out of 55 possible structures-is reached under full thermodynamic control and can be realized progressively (by combining progenitors, such as [Pd2A2C2] with [Pd2B2D2]), directly from ligands and PdII cations or by mixing all four corresponding homoleptic cages. The rational design of complex multicomponent assemblies that enables the modular incorporation of diverse chemical moieties will advance their applicability in functional nanosystems.

Pathway Complexity in Supramolecular Copolymerization and Blocky Star Copolymers by a Hetero-Seeding Effect

This study unravels the intricate kinetic and thermodynamic pathways involved in the supramolecular copolymerization of the two chiral dipolar naphthalene monoimide (NMI) building blocks (O-NMI and S-NMI), differing merely by a single heteroatom (oxygen vs sulfur). O-NMI exhibits distinct supramolecular polymerization features as compared to S-NMI in terms of its pathway complexity, hierarchical organization, and chiroptical properties. Two distinct self-assembly pathways in O-NMI occur due to the interplay between the competing dipolar interactions among the NMI chromophores and amide-amide hydrogen (H)-bonding that engenders distinct nanotapes and helical fibers, from its antiparallel and parallel stacking modes, respectively. In contrast, the propensity of S-NMI to form only a stable spherical assembly is ascribed to its much stronger amide-amide H-bonding, which outperforms other competing interactions. Under the thermodynamic route, an equimolar mixture of the two monomers generates a temporally controlled chiral statistical supramolecular copolymer that autocatalytically evolves from an initially formed metastable spherical heterostructure. In contrast, the sequence-controlled addition of the two monomers leads to the kinetically driven hetero-seeded block copolymerization. The ability to trap O-NMI in a metastable state allows its secondary nucleation from the surface of the thermodynamically stable S-NMI spherical "seed", which leads to the core-multiarmed "star" copolymer with reversibly and temporally controllable length of the growing O-NMI "arms" from the S-NMI "core". Unlike the one-dimensional self-assembly of O-NMI and its random co-assembly with S-NMI, which are both chiral, unprecedentedly, the preferred helical bias of the nucleating O-NMI fibers is completely inhibited by the absence of stereoregularity of the S-NMI "seed" in the "star" topology.

Kinetically controlled narcissistic self-sorting of Pd(II)-linked self-assemblies from structurally similar tritopic ligands

Although many examples of self-sorting have been reported, self-sorting of structurally similar building blocks is potentially difficult. Herein, we present the narcissistic self-sorted state from two kinds of structurally similar...

Acid-Activated Motion Switching of DB24C8 between Two Discrete Platinum(II) Metallacycles

The precise operation of molecular motion for constructing complicated mechanically interlocked molecules has received considerable attention and is still an energetic field of supramolecular chemistry. Herein, we reported the construction of two tris[2]pseudorotaxanes metallacycles with acid-base controllable molecular motion through self-sorting strategy and host-guest interaction. Firstly, two hexagonal Pt(II) metallacycles M1 and M2 decorated with different host-guest recognition sites have been constructed via coordination-driven self-assembly strategy. The binding of metallacycles M1 and M2 with dibenzo-24-crown-8 (DB24C8) to form tris[2]pseudorotaxanes complexes TPRM1 and TPRM2 have been investigated. Furthermore, by taking advantage of the strong binding affinity between the protonated metallacycle M2 and DB24C8, the addition of trifluoroacetic acid (TFA) as a stimulus successfully induces an acid-activated motion switching of DB24C8 between the discrete metallacycles M1 and M2. This research not only affords a highly efficient way to construct stimuli-responsive smart supramolecular systems but also offers prospects for precisely control multicomponent cooperative motion.

Sequence-controlled supramolecular copolymer constructed by self-sorting assembly of multiple noncovalent interactions

A sequence-controlled supramolecular copolymer was constructed by self-sorting assembly of metal coordination and two types of host–guest interactions.

Two-dimensional covalent organic frameworks with hierarchical porosity

This review highlights the state-of-the-art progress achieved in two-dimensional covalent organic frameworks (COFs) with hierarchical porosity, an emerging class of COFs constructed by integrating different types of pores into one framework.

Engineering orthogonality in the construction of an alternating rhomboidal copolymer with high fidelity via integrative self-sorting

An alternating rhomboidal copolymer was prepared through the combination of orthogonal self-assembly between metal-coordination and host-guest chemistry as well as integrative self-sorting strategy associated with molecular size and steric effect.

Threading carbon nanotubes through a self-assembled nanotube

Achieving the co-assembly of more than one component represents an important challenge in the drive to create functional self-assembled nanomaterials. Multicomponent nanomaterials comprised of several discrete, spatially sorted domains of components with high degrees of internal order are particularly important for applications such as optoelectronics. In this work, single-walled carbon nanotubes (SWNTs) were threaded through the inner channel of nanotubes formed by the bolaamphiphilic self-assembly of a naphthalenediimide-lysine (NDI-Bola) monomer. The self-assembly process was driven by electrostatic interactions, as indicated by ζ-potential measurements, and cation-π interactions between the surface of the SWNT and the positively charged, NDI-Bola nanotube interior. To increase the threading efficiency, the NDI-Bola nanotubes were fragmented into shortened segments with lengths of <100 nm via sonication-induced shear, prior to co-assembly with the SWNTs. The threading process created an initial composite nanostructure in which the SWNTs were threaded by multiple, shortened segments of the NDI-Bola nanotube that progressively re-elongated along the SWNT surface into a continuous radial coating around the SWNT. The resultant composite structure displayed NDI-Bola wall thicknesses twice that of the parent nanotube, reflecting a bilayer wall structure, as compared to the monolayer structure of the parent NDI-Bola nanotube. As a final, co-axial outer layer, poly(p-phenyleneethynylene) (PPE-SO3Na, M W = 5.76 × 104, PDI - 1.11) was wrapped around the SWNT/NDI-Bola composite resulting in a three-component (SWNT/NDI-Bola/PPE-SO3Na) composite nanostructure.

A nano-cocktail of an NIR-II emissive fluorophore and organoplatinum(ii) metallacycle for efficient cancer imaging and therapy

The scarcity of efficient imaging technologies for precise cancer treatment greatly drives the development of new nanotheranostic based platforms that enable both diagnostic and therapeutic functions, together in a single formulation. Owing to the complicated physiological microenvironment, nanosystems designed with the possibility of noninvasive real-time monitoring of therapeutic progression in the second near-infrared channel (NIR-II, 1000-1700 nm) could substantially improve the current cancer therapies. Herein, we design a novel NIR-II theranostic nanoprobe, PSY (size ∼110 nm), by incorporating organoplatinum(ii) metallacycles P1 and an organic NIR-II molecular dye, SY1030, into the FDA-approved polymer Pluronic F127. Preliminary in vitro and in vivo studies suggest that PSY is capable of being internalized into glioma U87MG-cells with no significant internalization in non-cancerous tissues. In addition, it shows excellent photostability and minimal background for real-time monitoring the process of therapy in the NIR-II region. Furthermore, in U87MG xenografts and orthotopic breast tumor, PSY demonstrat significantly improved anticancer efficacy compared to a clinically approved Pt(ii)-based anticancer drug, cisplatin. The engineered nano-cocktail PSY offers a simple strategy for delivering the organoplatinum(ii) macrocycle P1 and NIR-II fluorophore SY1030 as a cocktail of diagnostic and therapeutic functions and highlights its promising capacity for future cancer treatment.

Palladium(II)-Based Self-Assembled Heteroleptic Coordination Architectures: A Growing Family

Metal-driven self-assembly is one of the most effective approaches to lucidly design a large range of discrete 2D and 3D coordination architectures/complexes. Palladium(II)-based self-assembled coordination architectures are usually prepared by using suitable metal components, in either a partially protected form (PdL') or typical form (Pd; charges are not shown), and designed ligand components. The self-assembled molecules prepared by using a metal component and only one type of bi- or polydentate ligand (L) can be classified in the homoleptic series of complexes. On the other hand, the less explored heteroleptic series of complexes are obtained by using a metal component and at least two different types of non-chelating bi- or polydentate ligands (such as L^a and L^b ). Methods that allow the controlled generation of single, discrete heteroleptic complexes are less understood. A survey of palladium(II)-based self-assembled coordination cages that are heteroleptic has been made. This review article illustrates a systematic collection of such architectures and credible justification of their formation, along with reported functional aspects of the complexes. The collected heteroleptic assemblies are classified here into three sections: 1) [(PdL')_m (L^a )_x (L^b )_y ]-type complexes, in which the denticity of L^a and L^b is equal; 2) [(PdL')_m (L^a )_x (L^b )_y ]-type complexes, in which the denticity of L^a and L^b is different; and 3) [Pd_m (L^a )_x (L^b )_y ]-type complexes, in which the denticity of L^a and L^b is equal. Representative examples of some important homoleptic architectures are also provided, wherever possible, to set a background for a better understanding of the related heteroleptic versions. The purpose of this review is to pave the way for the construction of several unique heteroleptic coordination assemblies that might exhibit emergent supramolecular functions.

Self-assemblies of nucleolipid supramolecular synthons show unique self-sorting and cooperative assembling process

The inherent control of the self-sorting and co-assembling process that has evolved in multi-component biological systems is not easy to emulate in vitro using synthetic supramolecular synthons. Here, using the basic component of nucleic acids and lipids, we describe a simple platform to build hierarchical assemblies of two component systems, which show an interesting self-sorting and co-assembling behavior. The assembling systems are made of a combination of amphiphilic purine and pyrimidine ribonucleoside-fatty acid conjugates (nucleolipids), which were prepared by coupling fatty acid acyl chains of different lengths at the 2'-O- and 3'-O-positions of the ribose sugar. Individually, the purine and pyrimidine nucleolipids adopt a distinct morphology, which either supports or does not support the gelation process. Interestingly, due to the subtle difference in the order of formation and stability of individual assemblies, different mixtures of supramolecular synthons and complementary ribonucleosides exhibit a cooperative and disruptive self-sorting and co-assembling behavior. A systematic morphological analysis combined with single crystal X-ray crystallography, powder X-ray diffraction (PXRD), NMR, CD, rheological and 3D X-ray microtomography studies provided insights into the mechanism of the self-sorting and co-assembling process. Taken together, this approach has enabled the construction of assemblies with unique higher ordered architectures and gels with remarkably enhanced mechanical strength that cannot be derived from the respective single component systems.

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

The synthesis of conjugates of perylene diimide (PDI) and naphthalene diimide (NDI) modified with two benzo-21-crown-7 ethers (B21C7) are herein described. Their self-assembly behavior in various solvents was investigated particularly in aqueous medium, due to the recently discovered hydrophilic properties of B21C7 crown macrocycle. An unexpected fluorescence quenching phenomenon was observed in the PDI-B21C7 macrocycle conjugate in chloroform. The detailed UV-vis absorption and fluorescence spectra of these PDI/NDI derivatives in different solvents as well as their morphologies were investigated.

Self-Assembled Amphiphilic Janus Double Metallacycle

A double metallacycle was prepared via the size-selective integrative self-sorting of four different building blocks driven by a reversible metal-ligand coordination interaction. A hydrophobic dendron was placed on a metallacycle and a hydrophilic dendron was attached to the other metallacycle, producing a two-faced Janus-type supramolecule with two distinct functionalities. In aqueous media, hierarchical self-assembly of the supramolecular system was induced by the combination of coordination interactions and hydrophobic-hydrophilic interactions resulting in the formation of micrometer-sized fiber-like structures, a morphology distinct from metallacycles bearing only one type of functionality. This study provides a versatile approach for the construction of Janus-type molecules and demonstrates that integrative self-sorting of a supramolecular coordination system can be utilized for the preparation of complex supramolecular systems with predesigned functionalities and morphologies.

Selective Metal-Phenolic Assembly from Complex Multicomponent Mixtures

Selective self-assembly in multicomponent mixtures offers a method for isolating desired components from complex systems for the rapid production of functional materials. Developing approaches capable of selective assembly of "target" components into intended three-dimensional structures is challenging because of the intrinsically high complexity of multicomponent systems. Herein, we report the selective coordination-driven self-assembly of metal-phenolic networks (MPNs) from a series of complex multicomponent systems (including crude plant extracts) into thin films via metal chelation with phenolic ligands. The metal (Fe^III) selectively assembles low abundant phenolic components (e.g., myricetrin and quercetrin) from plant extracts into thin films. This selective metal-phenolic assembly is independent of the substrate properties (e.g., size, surface charge, and shape). Moreover, the high selectivity is consistent across different target phenolic ligands in model mixtures, even though each individual component can form thin films from single-component systems. A computational simulation of film formation suggests that the driving force for the selective behavior stems from differences in the number of chelating sites in the phenolic structures. The MPN films are shown to demonstrate improved antioxidant properties compared with the corresponding phenolic compounds in their free form, therefore exhibiting potential as free-standing antioxidant films.

Supramolecular Gel Based on Crown-Ether-Appended Dynamic Covalent Macrocycles

A new type of dynamic covalent macrocycle with self-promoted supramolecular gelation behavior is developed. Under oxidative conditions, the dithiol compound containing a diamide alkyl linker with an odd number (7) of carbon chain and an appended crown ether shows a remarkable gelation ability in acetonitrile, without any template molecules. Due to the existence of crown ethers and disulfide bonds, the obtained gel shows a multiple stimuli-responsiveness behavior. The mechanical properties and reversibility of the gel are investigated. Computational modeling suggests that the peripheral chain for diamide hydrogen bonding is responsible for the gelation process.

Porphyrin-functionalized coordination star polymers and their potential applications in photodynamic therapy

We present a new family of porphyrin-functionalized coordination star polymers prepared through combination of coordination-driven self-assembly and post-assembly polymerization. Their self-assembly behaviour in water and potential for photodynamic therapy were demonstrated.

Heterorotaxanes

Heterorotaxanes, in which at least two types of macrocycles were introduced as the wheel components in rotaxanes, have attracted more and more attention during the past few decades owing to their unique structural features and intriguing properties. The coexistence of varied macrocycles endows the resultant heterorotaxanes not only versatile shuttling and switching behaviors but also great potential for the construction of functional rotaxane systems for applications. In this feature article, a survey of the successful synthesis of heterorotaxanes will be provided based on the various strategies towards the synthesis of heterorotaxanes, i.e. orthogonal binding approach, self-sorting approach, cooperative capture approach, active metal template approach, etc.

Construction of Stimuli-Responsive Functional Materials via Hierarchical Self-Assembly Involving Coordination Interactions

Supramolecular self-assembly, which creates the ordered structures as a result of spontaneous organization of building blocks driven by noncovalent interactions (NCIs), is ubiquitous in nature. Recently, it has become increasingly clear that nature often builds up complex structures by employing a hierarchical self-assembly (HSA) strategy, in which the components are brought together in a stepwise process via multiple NCIs. Inspired by the dedicated biological structures in nature, HSA has been widely explored to construct well-defined assemblies with increasing complexity. The employment of direct metal-ligand bonds to drive the formation of discrete metallosupramolecular architectures has proven to be a highly efficient strategy to prepare structurally diverse architectures like two-dimensional (2-D) polygons and three-dimensional (3-D) polyhedra with well-defined shapes, sizes, and geometries. Such well-defined organometallic assemblies provide an ideal platform for designing novel artificial supramolecular systems with the increasing complexity though HSA. The presence of a well-defined organometallic scaffold brings an additional dimension to the final nanoscale structures. Moreover, the multilevel dynamic nature of hierarchical self-assemblies brings more structural and functional possibilities of resultant supramolecular systems. This Account will focus on our recent advance on construction of stimuli-responsive functional materials through HSA involving coordination interactions. In our study, a series of functionalized metallacycles were first constructed through coordination-driven self-assembly (CDSA). Then, the secondary noncovalent interaction sites were integrated within the functionalized metallacycle system via either preassembly or postassembly approach. Different segments, such as alkyl chains, dendrimers, cholesteryl moiety, covalent macrocycles, and even polymeric fragments, which could provide hydrophobic and hydrophilic interactions, van der Waals forces, hydrogen bonding, CH-π and π-π interactions, and host-guest interactions, have been utilized to provide the secondary NCIs. Further self-assembly of functionalized metallacycles gives rise to the formation of complex higher-order structures driven by other NCIs by taking advantages of orthogonal property of coordination bonds with other NCIs. By changing the type of additional NCIs embodied in building blocks, different supramolecular architectures, such as the ordered nanostructures, supramolecular polymers and gels, fluorescent materials and sensors, have been successfully prepared with the tailored chemical and physical properties. In particular, the dynamic nature of coordination bonds as well as other NCIs endows final assemblies with stimuli-responsive functions. Collectively, our studies suggest that combining coordination and other NCIs in a well-defined and precise manner is a highly efficient strategy to achieve the complex architectures and functional materials. Therefore, it is very promising to develop the desired functional materials with high precision and fidelity by employing HSA involving coordination interactions.

Truncated Sierpiński Triangular Assembly from a Molecular Mortise-Tenon Joint

The amalgamation of different components into a giant and intricate structure that makes quantitative and spontaneous assembly through molecular design is indispensable but challenging. To construct novel metallo-supramolecular architectures, here we present an architectural design principle based on multicomponent self-assembly. Using a carefully designed hexatopic terpyridine-based metallo-organic ligand (MOL), [Ru₂T₂K], we report on the formation of supramolecular trapezoid Zn₅[Ru₂T₂K]V₂, hollow hexagon Zn₁₅[Ru₂T₂K]₃K₃, and giant star-shaped supramolecule Zn₁₈[Ru₂T₂K]₃[Ru₂X₂V]₃, all of which were assembled by one-pot, nearly quantitative assembly of [Ru₂T₂K] with the ditopic 60°-directed bisterpyridine V, tetrakisterpyridine K, and MOL [Ru₂X₂V], respectively. The complementary ligands were selected on the basis of the size- and shape-fit principles, actually similar to the mortise-tenon joint that aligns and locks the two complementary wood components. This strategy is expected to open the door to sophisticated designer supramolecules and nonbiological materials. The multivalent connections within the mutual ligands give rise to the formation of stable assemblies, which are unambiguously characterized by NMR, ESI-MS, TWIM-MS, and TEM analyses.

Integrative Self-Sorting: One-Pot Synthesis of a Hetero[4]rotaxane from a Daisy-Chain-Containing Hetero[4]pseudorotaxane

The structural complexity of mechanically interlocked molecules are very attractive to chemists owing to the challenges they present. In this article, novel mechanically interlocked molecules with a daisy-chain-containing hetero[4]rotaxane motif were efficiently synthesized. In addition, a novel integrative self-sorting strategy is demonstrated, involving an ABB-type (A for host, dibenzo-24-crown-8 (DB24C8), and B for guest, ammonium salt sites) monomer and a macrocycle host, benzo-21-crown-7 (B21C7), in which the assembled species in hydrogen-bonding-supported solvent only includes a novel daisy-chain-containing hetero[4]pseudorotaxane. The found self-sorting process involves the integrative recognition between B21C7 macrocycles and carefully designed components simultaneously containing two types of secondary ammonium ions and a host molecule, DB24C8 crown ether. The self-sorting strategy is integrative to undertake self-recognition behavior to form one single species of pseudorotaxane compared with the previous report. This self-sorting system can be used for the efficient one-pot synthesis of a daisy-chain-containing hetero[4]rotaxane in a good yield. The structure of hetero[4]rotaxane was confirmed by ¹ H NMR spectroscopy and high-resolution electrospray ionization (HR-ESI) mass spectrometry.

The cytochrome c–cyclo[6]aramide complex as a supramolecular catalyst in methanol

A hydrogen-bonded aromatic amide macrocycle forms a host–guest complex with cytochrome c, which acts as a supramolecular catalyst for the oxidation of benzhydrol even at low temperatures.

Thermosensitive Phase Behavior of Benzo-21-crown-7 and Its Derivatives

For designing water-soluble responsive materials, utilizing crown ethers as main building blocks has been rarely explored in contrast to their linear poly(ethylene glycol) counterparts. In the current study, we report the robust thermoresponsive properties of the benzo-21-crown-7 (B21C7) family with lower critical solution temperature (LCST) and upper critical solution temperature (UCST) behavior. Different substituent groups on the benzene ring exhibit significant effects on water solubility and thermoresponsiveness. B21C7 and its cyano derivative display LCST phenomena, while B21C7-based carboxylic acid derivative presents UCST followed by LCST phase behavior. Supramolecular interactions with KCl provide an additional tuning approach for this crown ether system. These results demonstrate that B21C7s can serve as an easily accessible toolbox to develop new thermosensitive systems and prepare thermally responsive materials.

Strategy for the Co-Assembly of Co-Axial Nanotube-Polymer Hybrids

Nanostructured materials having multiple, discrete domains of sorted components are particularly important to create efficient optoelectronics. The construction of multicomponent nanostructures from self-assembled components is exceptionally challenging due to the propensity of noncovalent materials to undergo structural reorganization in the presence of excipient polymers. This work demonstrates that polymer-nanotube composites comprised of a self-assembled nanotube wrapped with two conjugated polymers could be assembled using a layer-by-layer approach. The polymer-nanotube nanostructures arrange polymer layers coaxially on the nanotube surface. Femtosecond transient absorption (TA) studies indicated that the polymer-nanotube composites undergo photoinduced charge separation upon excitation of the NDI chromophore within the nanotube.

One-pot synthesis of hetero[6]rotaxane bearing three different kinds of macrocycle through a self-sorting process

A hetero[6]rotaxane bearing three different kinds of macrocycle is designed and successfully synthesized through a one-pot “click” reaction by employing a facile and efficient integrative self-sorting principle.

In this article, a six-component self-sorting process that involves three types of crown ether macrocycle and three types of cation guest molecule was carefully and thoroughly investigated. The six components include three kinds of crown ether, namely bis(p-phenylene-34-crown-10) (BPP34C10), dibenzo-24-crown-8 (DB24C8) and benzo-21-crown-7 (B21C7), and their corresponding cation guest molecules, namely a 4,4′-bipyridine dication (BPY²⁺) and dibenzylammonium (DBA) and benzylalkylammonium (BAA) ions, respectively. Based on this well-established highly selective six-component self-sorting process, a hetero[6]rotaxane bearing three different kinds of crown ether macrocycle was designed and successfully synthesized through a facile and efficient one-pot “click” stoppering strategy. Such work is proposed to be a significant advance in the construction of mechanically interlocked molecules with high structural complexity, as well as a good supplement in the areas of multi-component self-sorting and noncovalent self-assembly.

Structure, solution assembly, and electroconductivity of nanosized argento-organic-cluster/framework templated by chromate

In view of elucidating potential structures and assembly mechanism of silver clusters and silver cluster-based metal-organic frameworks, we prepared four argento-organic-clusters/frameworks where the structures were directed by chromate in the presence of different thiolates. All four structures with ^tBuC₆H₄S^-, SⁱBu^-, and SⁱPr^- consist of three core-shells, an inner CrO₄^2-, an intermediate Ag-S aggregate and finally the protective organic moieties. {(HNEt₃)₃[Ag(CrO₄)₄@Ag₄₆(SC₆H₄^tBu)₂₄(CF₃COO)₁₈(DMF)₄]} (1) is a supertetrahedron with an inner Ag(CrO₄)₄ tetrahedron shelled by four fused Ag_11.5S₆ lobes. [(CrO₄)₅@Ag₄₀(SⁱBu)₂₇(CF₃COO)₃]_n (2) is an undulated snake-like tube housing the infinite CrO₄^2- tetrahedra. [(CrO₄)₂@Ag₄₁(SⁱBu)₃₀(NO₃)₃(CN)₄]_n (3) forms an uncommon 7-connected kwh network incorporating hexagonal layers of Ag₁₉(SⁱBu)₁₅ balls with a single inner CrO₄^2- connected by another Ag atom. Both enantiomeric chiral qtz frameworks of [CrO₄@Ag₂₀(SⁱPr)₁₀(Cr₂O₇)₂(COOCF₃)₄(DMF)₄]_n (4) were structurally characterized. In 4, Cr₂O₇^2- connects the Ag₂₀(SⁱPr)₁₀ clusters with a trapped CrO₄^2- into a 3D quartz (qtz) structure, where the spherical cluster acts like oxygen and Cr₂O₇^2- takes the place of Si in SiO₂. Electrospray ionization mass spectrometry (ESI-MS) analysis of the reaction solutions of 1-4 clearly indicated that (i) the Ag(CrO₄)₄@Ag₄₆ core of 1 can retain its molecular structure in the solution and (ii) the chromate-templated polynuclear silver-thiolate species in solution are important building blocks to construct the 1D or 3D motif for 2-4. The electrochemistry in sulfuric acid and enhancement of the electrical conductivity upon I₂ doping have also been reported.

A Photoresponsive Orthogonal Supramolecular Complex Based on Host-Guest Interactions

We synthesized a novel green-light-responsive tetra-ortho-isopropoxy-substituted azobenzene (ipAzo). Cis-ipAzo forms a strong host-guest complex with γ-cyclo dextrin (γ-CD) whereas trans-ipAzo binds weakly. This new photoresponsive host-guest interaction is reverse to the well-known azobenzene (Azo)/α-cyclodextrin (α-CD) complex, which is strong only between trans-Azo and α-CD. By combining the UV-light-responsive Azo/α-CD and green-light-responsive ipAzo/γ-CD host-guest complexes, a photoresponsive orthogonal supramolecular system is developed.

Design of a flexible organometallic tecton: host–guest chemistry with picric acid and self-assembly of platinum macrocycles

A new “flexible” and ditopic Pt(ii) organometallic compound is a tecton for the self-assembly of neutral metallacycles. It also exhibits significant binding affinity for picric acid.

Surveying macrocyclic chemistry: from flexible crown ethers to rigid cyclophanes

This review features the progress made in the development of macrocycles since Pedersen's ground-breaking discovery of the crown ethers in 1967.

Controlled Orthogonal Self-Assembly of Heterometal-Decorated Coordination Cages

Multiple orthogonal coordinative interactions were utilized to construct heterometal-decorated tetrahedral cages from in situ formed trinuclear Zr^IV clusters through the combination with other metal ions such as Cu^II or Pd^II . Through effective use of the hard/soft acid/base principle, the orthogonal self-assembly process of Zr-bpydc-CuCl₂ (H₂ bpydc=2,2-bipyridine-5,5-dicarboxylic acid) can be finely controlled using three strategies: post-synthetic metallization, a stepwise metalloligand approach, or a one-pot reaction.

Face and edge directed self-assembly of Pd12 tetrahedral nano-cages and their self-sorting

Reactions of a cis-blocked Pd(ii) 90° acceptor [cis-(tmeda)Pd(NO3)2] (M) with 1,4-di(1H-tetrazol-5-yl)benzene (H2L1 ) and [1,3,5-tri(1H-tetrazol-5-yl)benzene] (H3L2 ) in 1 : 1 and 3 : 2 molar ratios respectively, yielded soft metallogels G1 and G2 [tmeda = N,N,N',N'-tetramethylethane-1,2-diamine]. Post-metalation of the gels G1 and G2 with M yielded highly water-soluble edge and face directed self-assembled Pd12 tetrahedral nano-cages T1 and T2, respectively. Such facile conversion of Pd(ii) gels to discrete tetrahedral metallocages is unprecedented. Moreover, distinct self-sorting of these two tetrahedral cages of similar sizes was observed in the self-assembly of M with a mixture of H2L1 and H3L2 in aqueous medium. The edge directed tetrahedral cage (T1) was successfully used to perform Michael reactions of a series of water insoluble nitro-olefins assisted by encapsulation into the cage in aqueous medium.