Giant Expanded Porous Metallo-Hexagons.

Molecular self-assembly is a widely recognized approach for fabricating biomimetic functional nanostructures. Here, we report the synthesis of two giant hollow coronoid-like supramolecular hexagons, and . These hexagons feature large cavities, showcasing unique inner and outer hexagons fixed by specific connectivities for enhanced stability and high metal center density.

Supramolecular cuboctahedra with aggregation-induced emission enhancement and external binding ability.

Beyond the AIE (aggregation-induced emission) phenomenon in small molecules, supramolecules with AIE properties have evolved in the AIE family and accelerated the growth of supramolecular application diversity. Inspired by its mechanism, particularly the RIV (restriction of intramolecular vibrations) process, a feasible strategy of constructing an AIE-supramolecular cage based on the oxidation of sulfur atoms and coordination of metals is presented. In contrast to previous strategies that used molecular stacking to limit molecular vibrations, we achieved the desired goal using the synergistic effects of coordination-driven self-assembly and oxidation.

Author Correction: Intra- and intermolecular self-assembly of a 20-nm-wide supramolecular hexagonal grid.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Assembling Shape-Persistent High-Order Sierpiński Triangular Fractals.

Fractals are a series of intricate patterns with aesthetic, mathematic, and philosophic significance. The Sierpiński triangles have been known for more than one hundred years, but only recently discrete shape-persistent low-generation (mainly ST-1) fractal supramolecules have been realized. Herein, we report a retro-assembly pathway to the nanometer-scale, supra-macromolecular second-generation Sierpiński triangle and its third-generation saturated counterpart (Pascal's triangle).

Intra- and intermolecular self-assembly of a 20-nm-wide supramolecular hexagonal grid.

For the past three decades, the coordination-driven self-assembly of three-dimensional structures has undergone rapid progress; however, parallel efforts to create large discrete two-dimensional architectures-as opposed to polymers-have met with limited success. The synthesis of metallo-supramolecular systems with well-defined shapes and sizes in the range of 10-100 nm remains challenging. Here we report the construction of a series of giant supramolecular hexagonal grids, with diameters on the order of 20 nm and molecular weights greater than 65 kDa, through a combination of intra- and intermolecular metal-mediated self-assembly steps.

Giant Truncated Metallo-Tetrahedron with Unexpected Supramolecular Aggregation Induced Emission Enhancement.

The artificial synthesis of giant, three-dimensional, and shell-like architectures with growing complexity and novel functionalities is an especially challenging task for chemists. Fullerenes and self-assembled cages are remarkable examples that are proven milestones in the field of functional materials. Herein, we present another unique system: a giant terpyridine-based truncated metallo-tetrahedral architecture that includes densely-packed ionic pairs with a significant internal cavity.

Sierpiński Pyramids by Molecular Entanglement.

Planar, terpyridine-based metal complexes with the Sierpiński triangular motif and alkylated corners undergo a second self-assembly event to give megastructural Sierpiński pyramids; assembly is driven by the facile lipophilic-lipophilic association of the alkyl moieties and complementary perfect fit of the triangular building blocks. Confirmation of the 3D, pyramidal structures was verified and supported by a combination of TEM, AFM, and multiscale simulation techniques.

Vertical Assembly of Giant Double- and Triple-Decker Spoked Wheel Supramolecular Structures.

The double- or triple-decker 3D metallo-hexagons were obtained by self-assembly of multitopic tris-terpyridines with Cd ions in near-quantitative yield. Comprising up to 72 ionic pairs, the multiple spoked wheels display characteristic reversible gelation properties under thermodynamic conditions. The supramolecular metallo-nanoarchitectures were characterized by H NMR, 2D NMR (COSY and NOESY), and diffusion-ordered spectroscopy (DOSY) and HR-ESI-MS, traveling-wave ion mobility mass spectrometry (TWIM-MS), TEM, and AFM.

Supramolecular arrays by the self-assembly of terpyridine-based monomers with transition metal ions.

Hierarchical construction of a highly ordered supramolecular array has been, in general, a challenge due to the complexation of building blocks and the hard-to-control weak interactions. Herein, we present a type of well-ordered nanoribbon, which was self-assembled via shape complimentary and hydrophobic effects from the bowl-shaped supramolecular components, which were synthesized by combining designer terpyridine-based monomers and two different metal ions (Ru2+, Zn2+). Interestingly, switching counter ions or changing monomer concentrations, a transformation between a uniform nanosphere and nanoribbon occurred.

Terpyridine-based metallosupramolecular constructs: tailored monomers to precise 2D-motifs and 3D-metallocages.

This overview represents a comprehensive summary of the recent developments in the growing field of terpyridine-based, discrete metallosupramolecular architectures. The N-heteroaromatic ligand [2,2':6',2'']terpyridine (tpy) presents a convergent N,N',N''-chelating donor set and has the ability to bind diverse metal ions to form stable pseudo-octahedral tpy-M2+-tpy bonds. Use of tpy-M2+-tpy connectivity for the edges and directed organic vertices has opened the door to diverse, dynamic, utilitarian macromolecular materials.

Concentration dependent supramolecular interconversions of triptycene-based cubic, prismatic, and tetrahedral structures.

The quantitative, single step, self-assembly of a shape-persistent, three-dimensional C3v-symmetric, triptycene-based tris-terpyridinyl ligand initially gives a platonic-based cubic architecture, which was unequivocally characterized by 1D and 2D NMR spectroscopy, mass spectrometry, and single crystal X-ray structural analysis. The unique metal-ligand binding properties of the Cd2+ analogue of this construct give rise to a concentration-dependent dynamic equilibrium between cube, prism, and tetrahedron-shaped architectures. Dilution transforms this cube into two identical tetrahedra through a stable prism-shaped intermediate; increasing the concentration reverses the process.

Supercharged, Precise, Megametallodendrimers via a Single-Step, Quantitative, Assembly Process.

Synthesis of giant unimolecular dendrimers is challenging due, in part, to difficulties encountered at higher generations, in both convergent and divergent protocols because of the multistep construction/purification process. Herein, we report a hybrid synthetic procedure in which the core is constructed last. This quantitative assembly generated a metallodendrimer that is supercharged (120+), large (11.

Metallosupramolecular 3D assembly of dimetallic Zn[RuL] and trimetallic FeZn[RuL].

A novel metallo-organic ligand [RuL] with four uncomplexed coordination sites was created, and upon treatment with Zn generated a dimetallic 3D metallosupramolecule in nearly quantitative yield. This self-assembly process gave stable intermediates, opening the pathway to the first 3D metallo-assembly possessing two Ru, two Fe, and two Zn ions precisely located in the different edges. This strategy opens the door to novel designer 3D polymetallic constructs capable of diverse applications.

Constructing High-Generation Sierpiński Triangles by Molecular Puzzling.

Three generations of metalated trigonal supramolecular architectures, so-called metallo-triangles, were assembled from terpyridine (tpy) complexes. The first generation (G1) metallo-triangles were directly obtained by reacting a bis(terpyridinyl) ligand with a 60° bite angle and Zn ions. The direct self-assembly of G2 and G3 triangles by mixing organic ligands and Zn , however, only generated a mixture of G1 and G2, as well as a trace amount of insoluble polymer-like precipitate.

Stepwise, multicomponent assembly of a molecular trapezoid possessing three different metals.

A novel terpyridine-based, trapezoidal architecture was synthesized by a coordination-driven multicomponent assembly and features three different tpy-M-tpy bonds (M = Ru, Fe, and Zn) in the macrocyclic ring. This trimetallic macrocycle introduces the construction of polymetallosupramolecular assemblies possessing multiple, differing metal centers in an ordered, predetermined pattern. Characterization was accomplished by NMR spectroscopy, mass spectrometry, and UV-Vis spectroscopy.

Self-assembly of a supramolecular hexagram and a supramolecular pentagram.

Five- and six-pointed star structures occur frequently in nature as flowers, snow-flakes, leaves and so on. These star-shaped patterns are also frequently used in both functional and artistic man-made architectures. Here following a stepwise synthesis and self-assembly approach, pentagonal and hexagonal metallosupramolecules possessing star-shaped motifs were prepared based on the careful design of metallo-organic ligands (MOLs).

Terpyridine-Based, Flexible Tripods: From a Highly Symmetric Nanosphere to Temperature-Dependent, Irreversible, 3D Isomeric Macromolecular Nanocages.

A three-dimensional, highly symmetric sphere-like nanocage was synthesized using a terpyridine (tpy)-based, flexible tris-dentate ligand and characterized by single crystal X-ray analysis. To introduce more rigidity, one of the tpy units of the tris-dentate ligand was preblocked by stable connectivity to form the corresponding Ru-dimer. The complexation between Ru-dimer and Fe demonstrates an unexpected temperature-dependent assembly between two irreversible isomeric 3D nanocages.

Controlled Interconversion of Superposed-Bistriangle, Octahedron, and Cuboctahedron Cages Constructed Using a Single, Terpyridinyl-Based Polyligand and Zn(2.).

Metallomacromolecular architectural conversion is expanded by the characterization of three different structures. A quantitative, single-step, self-assembly of a shape-persistent monomer, containing a flexible crown ether moiety, gives an initial Archimedean-based cuboctahedron that has been unequivocally characterized by 1D and 2D NMR spectroscopy, mass spectrometry, and collision cross section analysis. Both dilution and exchange of counterions, transforms this cuboctahedron into two identical octahedrons, which upon further dilution convert into four, superposed, bistrianglar complexes; increasing the concentration reverses the process.

Mono- and Bis-Terpyridine-Based Dimer and Metallo-Organic Polymers as Ionic Templates for Preparation of Multi-Metallic Au Nanocluster and Nanowires.

The preparation of multi-metallic Au nanocluster and nanowires has been achieved using terpyridine-based metallo-organic polymers as multi-ionic templates through a straightforward counterion exchange with aqueous NaAuCl4 followed by a mild reduction in-situ with sodium citrate. The mild reduction of the [TpyFeTpy]2+ x 2[AuCl4]- complex, derived from [TpyFeTpy]2+ x 2Cl- 1 (tpy = 2,2':6',2"-terpyridine), led to the formation of Au nanoclusters (Au NC) with diameters ranging from 7.5-88 nm.

3D helical and 2D rhomboidal supramolecules: stepwise self-assembly and dynamic transformation of terpyridine-based metallo-architectures.

A Ru(2+)-connected, metallo-organic ligand (L) with three free terpyridines was designed and synthesized. L was assembled with Zn(2+) to generate a helical structure; however, when mixing L with a 1,2,3-tristerpyridine ligand (T), a thermodynamically stable 2D rhombus was assembled. Furthermore, this 2D rhomboidal structure can also be achieved through the dynamic transformation of preassembled helix H with T and Zn(2+) at room temperature.

Characterization of Metallosupramolecular Polymers by Top-Down Multidimensional Mass Spectrometry Methods.

Top-down multidimensional mass spectrometry, interfacing electrospray ionization (ESI) with ion mobility mass spectrometry (IM-MS), and energy resolved (gradient) tandem mass spectrometry (gMS(2) ) are employed to characterize the stoichiometries, architectures, and intrinsic stabilities of coordinatively bound supramolecular polymers containing terpyridine functionalized ligands. As a soft ionization method, ESI prevents or minimizes unwanted assembly destruction. The IM dimension affords separation of the supramolecular ions by charge and collision cross-section (a function of size and shape).

Multicomponent reassembly of terpyridine-based materials: quantitative metallomacrocyclic rearrangement.

Mixing of metallocyclic trimers and tetramers in an exact 1 : 1.5 stoichiometry provided new supramolecular triangles in quantitative yields. Characterization of the new hetero-nuclear metallomacrocycles was achieved by (1)H, 2D-COSY, 2D-NOESY, and (13)C NMR spectroscopy, along with ESI and TWIM mass spectrometry.

Precise Molecular Fission and Fusion: Quantitative Self-Assembly and Chemistry of a Metallo-Cuboctahedron.

Inspiration for molecular design and construction can be derived from mathematically based structures. In the quest for new materials, the adaptation of new building blocks can lead to unexpected results. Towards these ends, the quantitative single-step self-assembly of a shape-persistent, Archimedean-based building block, which generates the largest molecular sphere (a cuboctahedron) that has been unequivocally characterized by synchrotron X-ray analysis, is described.

A TpyRu²⁺-based bismetallopolymer and its performance in catalytic water oxidation (Tpy = 4-(p-methoxyphenyl)-2,2':6',2''-terpyridine).

A bismetallo-organic polymer was successfully prepared by treating a metallo-ligand with Ag(+); characterization was accomplished by NMR, UV-vis, and single crystal X-ray analyses. This heteronuclear polymer achieved more than a two-fold turnover number (TON) and a faster reaction rate in comparison to a Ce-driven Ru-monomer in catalytic water oxidation.