Stepwise Synthesis of Low-Symmetry Hexacationic Pyridinium Organic Cages.

An efficient approach was developed for the synthesis of the well-known BlueCage by pre-bridging two 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT) panels with one linker followed by cage formation in a much improved yield and shortened reaction time. Such a stepwise methodology was further applied to synthesize three new pyridinium organic cages, , , and , where the low-symmetry cages and with angled panels demonstrated better recognition properties toward 1,1'-bi-2-naphthol (BINOL) than the high-symmetry analogue featuring parallel platforms.

Counteranion-mediated efficient iodine capture in a hexacationic imidazolium organic cage enabled by multiple non-covalent interactions.

Developing efficient adsorbents to capture radioactive iodine produced from nuclear wastes is highly desired. Here we report the facial synthesis of a hexacationic imidazolium organic cage and its iodine adsorption properties. Crucial role of counteranions has been disclosed for iodine capture with this cage, where distinct iodine capture behaviors were observed when different counteranions were used.

A PdL cage containing Brønsted-base active sites for the one-pot photooxidation/Knoevenagel condensation reaction.

Brønsted-base active sites on a PdL cage facilitates enhanced catalytic efficiency, wide substrate scope and high turnover number (TON) for the one-pot photooxidation/Knoevenagel condensation reaction under mild conditions.

Dynamic Interconversion and Induced-Fit Guest Binding with Two Macrocycle-Based Coordination Cages.

We report the syntheses and host-guest chemistry of two interconvertible coordination cages, PdL and PdL, from a dynamic macrocycle ligand (L) and a cis-blocking (tmen)Pd(NO) (tmen = tetramethylethylenediamine) unit (Pd). The water-soluble macrocyclic L, which can bind various polycyclic aromatic hydrocarbon (PAH) guests in its cis-conformation, was constructed via four pyridinium bonds between two 2,4,6-tri(4-pyridyl)-1,3,5-triazine [TPT] panels and two -xylene bridges. We selectively formed each cage either by changing the reaction concentration/solvent/temperature or through induced-fit guest encapsulation, while direct assembly of L and Pd resulted in a mixture of PdL and PdL in equilibrium.

Stereocontrolled Self-Assembly of Ln(III)-Pt(II) Heterometallic Cages with Temperature-Dependent Luminescence.

Structurally well-defined discrete d/f heterometallic complexes show diverse application potential in electrooptic and magnetic materials. However, precise control of the component and topology of such heterometallic compounds with fine-tuned photophysical properties is still challenging. Herein, we report the stereocontrolled syntheses of a series of Ln-Pt heterometallic cages through coordination-driven self-assembly of enantiopure alkynylplatinum-based metalloligands (L, L) with lanthanide ions (Ln = Eu, Yb, Nd, Lu).

An Organo-Palladium Host Built from a Dynamic Macrocyclic Ligand: Adaptive Self-Assembly, Induced-Fit Guest Binding, and Catalysis.

Artificial hosts with rich conformational dynamics are attractive to supramolecular chemists due to their adaptive guest-binding properties and enzyme-like catalytic functions. We report here the adaptive self-assembly and host-guest catalysis of a new water-soluble organo-palladium host (Pd L ) built from a pyridinium-bonded macrocyclic ligand (L) and cis-blocked palladium corners (Pd). While the direct self-assembly of L with Pd gives rise to a dynamic mixture of products, both neutral polyaromatic hydrocarbons and an anionic polyoxometalate cluster (W O ) can template the dominant formation of the Pd L host.

Shape Complementary Coordination Self-Assembly of a Redox-Active Heteroleptic Complex.

We present here the coordination self-assembly of a new heteroleptic coordination complex () from one novel pyridinium-functionalized bis-2,4,6-tris(pyridin-3-yl)-1,3,5-triazine (bis-3-TPT, ) macrocyclic ligand, two separate 3-TPT () ligands, and four -blocking bpyPd(NO) (bpy = 2,2'-bipyridine). While homoleptic self-assemblies with either or gave dynamic mixtures of products, a single thermodynamic heteroleptic complex was obtained driven by the shape complementarity of building blocks. Moreover, the redox-active nature of the heteroleptic assembly facilitates the highly efficient catalytic aerobic photo-oxidation of aromatic secondary alcohols under mild conditions.

Combinatorial Self-Assembly of Coordination Cages with Systematically Fine-Tuned Cavities for Efficient Co-Encapsulation and Catalysis.

Controllable arrangement of different ligands in a single assembly will not only bring increased complexity but also offers a new route to fine-tune the function of the designed architecture. We report here a combinatorial self-assembly with enPd(NO ) and three different ligands (L ), which gave rise to a family of six palladium-organic cages (C1-6) with systematically varied shapes and cavities, including three new heteroleptic (Pd L L , Pd L L , Pd L L ), one new homoleptic (Pd L ) cages, and two known homoleptic (Pd L , Pd L ) cages. Emergent functions due to the fusion of two half cavities on the heteroleptic cages from their parent homoleptic cages have been observed: the heteroleptic cages can form ternary complexes by co-encapsulation of both aromatic and aliphatic guests, while their homoleptic counterparts can only form binary complexes.

Guest-Driven Self-Assembly and Chiral Induction of Photofunctional Lanthanide Tetrahedral Cages.

Chiral luminescent lanthanide-organic cages have many potential applications in enantioselective recognition, sensing, and asymmetric catalysis. However, due to the paucity of structures and their limited cavities, host-guest chemistry with lanthanide-organic cages has remained elusive so far. Herein, we report a guest-driven self-assembly and chiral induction approach for the construction of otherwise inaccessible LnL-type (Ln = lanthanide ions, i.

Cation modulated spin state and near room temperature transition within a family of compounds containing the same [FeL] center.

Spin-crossover (SCO) active compounds have received much attention due to their potential application in molecular devices. Herein, a family of solvent-free Fe compounds, formulated as (A)[FeL], (HL = pyridine-2,6-bi-tetrazolate, A = (Me)N1, EtNH2, PrNH3 and PrNH4), were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that 1-4 are all supramolecular frameworks containing the same [FeL] center, which is arranged into two packing modes inter-molecular interactions, that is, a 3D architecture in 1 and 1D chain in 2-4.

Photooxidase Mimicking with Adaptive Coordination Molecular Capsules.

One important feature of enzyme catalysis is the induced-fit conformational change after binding substrates. Herein, we report a biomimetic water-soluble molecular capsule featuring adaptive structural change toward substrate binding, which offers an ideal platform for efficient photocatalysis. The molecular capsule was coordination-assembled from three anthracene-bridged bis-TPT [TPT = 2,4,6-tris(4-pyridyl)-1,3,5-triazine] ligands and six (bpy)Pd(NO) (bpy = 2,2'-bipyridine).

Designing a highly stable coordination-driven metallacycle for imaging-guided photodynamic cancer theranostics.

Coordination-driven self-assembly features good predictability and directionality in the construction of discrete metallacycles and metallacages with well-defined sizes and shapes, but their medicinal application has been limited by their low stability and solubility. Herein, we have designed and synthesized a highly stable coordination-driven metallacycle with desired functionality derived from a perylene-diimide ligand a spontaneous deprotonation self-assembly process. Brilliant chemical stability and singlet oxygen production ability of this emissive octanuclear organopalladium macrocycle make it a good candidate toward biological studies.

Hexameric Lanthanide-Organic Capsules with Tertiary Structure and Emergent Functions.

Biological macromolecules always function through a collective behavior of the aggregated constituents, which usually are self-assembled together via noncovalent interactions. Likewise, artificial supramolecular assemblies, whose properties and functions are mainly derived from their primary and secondary structures, may also aggregate into high-order architectures with emergent functions not available on the individual components. Here we report the first example of an insulin-like hexamerization of lanthanide triple helicates toward a 4 nm diameter hexameric capsule via consecutive metal-directed and anion-directed assembly processes.

Controlled Self-Assembly and Multistimuli-Responsive Interconversions of Three Conjoined Twin-Cages.

Stimuli-responsive structural transformations between discrete coordination supramolecular architectures not only are essential to construct smart functional materials but also provide a versatile molecular-level platform to mimic the biological transformation process. We report here the controlled self-assembly of three topologically unprecedented conjoined twin-cages, i.e.

Self-Assembly of Lanthanide-Covalent Organic Polyhedra: Chameleonic Luminescence and Efficient Catalysis.

A series of multinuclear lanthanide-covalent organic polyhedra (LnCOPs), including pillar-typed triangular prisms and tetrahedra (Ln = La, Sm, Eu), have been constructed for the first time, through either one-pot subcomponent self-assembly or postassembly metalation. In contrast to the known tetrahedral cages based on transition metals, the pillar-typed polyhedra were favored from the same organic components in the presence of lanthanides. Besides this, facile transmetalations between the polyhedra endow cascade chameleonic luminescence.

Guest-Reaction Driven Cage to Conjoined Twin-Cage Mitosis-Like Host Transformation.

We report here a guest-reaction-induced mitosis-like host transformation from a known Pd L cage 1 to a conjoined Pd L twin-cage 2 featuring two separate cavities. The encapsulation of 1-hydroxymethyl-2-naphthol (G1), a known ortho-quinone methide (o-QMs) precursor, within the hydrophobic cavity of cage 1 is found crucial to realize the cage to twin-cage conversion. Confined G1 molecules within the nanocavity undergo self-coupling dimerization reaction to form 2,2'-dihydroxy-1,1'-dinaphthylmethane (G2) which then triggers the cage to twin-cage mitosis.

Coordination-Assembled Water-Soluble Anionic Lanthanide Organic Polyhedra for Luminescent Labeling and Magnetic Resonance Imaging.

Lanthanide-containing functional complexes have found a variety of applications in materials science and biomedicine because of their unique electroptical and magnetic properties. However, the poor stability and solubility in water of multicomponent lanthanide organic assemblies significantly limit their practical applications. We report here a series of water-stable anionic LnL-type ( = 2, 3, 4, and 5) lanthanide organic polyhedra (LOPs) constructed by deprotonation self-assembly of three fully conjugated ligands (HL and HL) featuring a 2,6-pyridine bitetrazolate chelating moiety.

Metal ion adaptive self-assembly of photoactive lanthanide-based supramolecular hosts.

A post-synthetic transmetallation self-assembly strategy was developed for the preparation of near infrared (NIR) emitting YbL cubes, which could not be synthesized through direct metal-ligand assembly procedures. Metal-adaptive critical structural transformations from LaL triangular prism to LnL cubes were observed along the lanthanide series, the latter of which showed size-selective guest binding behaviour toward poly-aromatic hydrocarbon (PAH) molecules.

Chiral auxiliary and induced chiroptical sensing with 5d/4f lanthanide-organic macrocycles.

A stereocontrolled self-assembly of 5d/4f heterometal-organic macrocycles has been realized by a post-assembly chiral auxiliary approach. Interligand π-π stacking interactions promoted chiral transfer from point-chirality of the auxiliary ligand to metal centers and then the helicates to produced CD and CPL active europium assemblies, facilitating a feasible enantiomeric excess determination by induced chiroptical signals.

Metallopolymers cross-linked with self-assembled LnL cages.

Herein, we fabricated a hybrid PDVB-LnL metallopolymer using a vinyl functionalized lanthanide-organic tetrahedral cage as the cross-linking agent. Such a covalent embedding strategy not only tunes the morphology and porosity of the metallopolymer, but also improves the luminescence property of the lanthanide organic polyhedron. Potential application in lanthanide separation has also been demonstrated.

Stereocontrolled self-assembly and photochromic transformation of lanthanide supramolecular helicates.

Stereocontrolled self-assembly of a dinuclear triple-stranded europium helicate (Eu2L3) based on DTE-functionalized ligands has been achieved via the chiral-induction strategy. The point-chirality of the ligands is transferred to give either Δ or Λ metal-centers and hence leads to the overall P or M helical senses. CD spectroscopy and NMR enantiomeric differentiation experiments have confirmed the formation of enantiomers.

Hierarchical Self-Assembly and Chiroptical Studies of Luminescent 4d-4f Cages.

Multinuclear lanthanide-containing supramolecular cages have received increasing attention recently because of their unique electroptical and magnetic properties. Here we report the hierarchical self-assembly and chiroptical studies of a group of 4d-4f heterometallic cages synthesized from a preformed dimetalloligand [(bpy)Pd1] (2) (bpy = 2,2-bipyridine) and a variety of trivalent lanthanide ions (Ln = Nd, Eu, Yb). The programmable self-assembly process leading to the trigonal bipyramidal cages formulated as {Ln[(bpy)Pd1]} (3) has been confirmed by one- and two-dimensional NMR, electro-spray-ionization time-of-flight mass-spectroscopy, and in one typical case by single-crystal X-ray diffraction studies.

Self-Assembled Bright Luminescent Lanthanide-Organic Polyhedra for Ratiometric Temperature Sensing.

Luminescent lanthanide-containing compounds have a lot of stimulating applications. However, the fine-tuning of the optical properties of multi-nuclear lanthanide edifices is still a big challenge. We report here the coordination self-assembly of a group of bright luminescent lanthanide organic polyhedra (LOPs) with record high emission quantum yields, by using two fully-conjugated ligands featuring the triazole-pyridine-amido (tpa) chelating moiety, easily-accessible from the "Click" reaction.

Water-Soluble Redox-Active Cage Hosting Polyoxometalates for Selective Desulfurization Catalysis.

Transformations within container-molecules provide a good alternative between traditional homogeneous and heterogeneous catalysis, as the containers themselves can be regarded as single molecular nanomicelles. We report here the designed-synthesis of a water-soluble redox-active supramolecular PdL cage and its application in the encapsulation of aromatic molecules and polyoxometalates (POMs) catalysts. Compared to the previous known PdL cage, our results show that replacement of two cis-blocked palladium corners with p-xylene bridges through pyridinium bonds formation between the 2,4,6-tri-4-pyridyl-1,3,5-triazine (TPT) ligands not only provides reversible redox-activities for the new PdL cage, but also realizes the expansion and subdivision of its internal cavity.

Self-Assembly of a Tetraphenylethylene-Based Capsule Showing Both Aggregation- and Encapsulation-Induced Emission Properties.

Functional molecular capsules have attracted a lot of attention in recent years because of their potential applications as chemosensors, catalysis, drug carriers, and so on. We report here the coordination-directed self-assembly of a fluorescent-lantern-type molecular capsule from four tetraphenylethylene-based ditopic ligands and two square-planar palladium(II) ions. The capsule has been thoroughly characterized by UV-vis, 1D/2D NMR, electrospray ionization time-of-flight mass spectrometry, and single-crystal X-ray diffraction studies.