Search

This review provides a detailed insight into the smart selection of spacer material and preparation technique in a plasmonic–fluorophore hybrid system to tailor the system for a desired application, mainly targeting active photoluminescence tuning.

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. Upon assembling with zinc ions, S1 was endowed with a distinct AIE property compared with its ligand L1, while S2 exhibited a remarkable fluorescence enhancement compared to L2. Also, the single cage-sized nanowire structure of supramolecules was obtained

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. The hexagonal intermediates and the resulting self-assembled grid architectures were imaged at submolecular resolution by scanning tunnelling microscopy. Characterization (including by scanning tunnelling spectroscopy) enabled the unambiguous atomic-scale determination of fourteen hexagonal grid isomers. Metal-mediated self-assembly in solution typically leads to small two- and three-dimensional architectures on scales smaller than 10 nm, but now a series of large, discrete, two-dimensional supramolecular hexagonal grids have been prepared through a combination of intra- and intermolecular coordination interactions. These 20-nm-wide grids have been imaged at submolecular resolution using scanning tunnelling microscopy.

Three bimetallic triangles were constructed via a step-wise assembly of tailored terpyridine building blocks. Oligomeric trimer 2 was obtained by reacting ligand 1 with Ru(II). Subsequent cyclization of trimer 2 with Zn(II), Cd(II), and Fe(II) resulted in the formation of bimetallic triangles 3, 4, and 5 in high yield, respectively. All triangles were characterized by NMR spectroscopy, ESI and travelling-wave ion mobility-mass spectrometry (MS), as well as gradient MS, which provided insight into their stabilities.

The electrochemical polymerization of Ru-containing monomers generates polymers on semiconductor or electrode surfaces. The different techniques to prepare such thin metallopolymer films are summarized in this chapter. As before, the proposed applications, such as opto-electronics, catalysis or sensing, are evaluated.

The blending of Ru complexes in polymers represents a straightforward alternative to the covalent or coordinative incorporation into polymer architectures. Though applications in the fields of opto-electronics (e.g., light-emitting electrochemical cells or diodes) or catalysis have been reported, an intrinsic limitation remains, which is bleaching. These aspects are discussed in this chapter. Furthermore, polymer staining is worth mentioning. The reaction between Ru species and polymers increases the electron-density contrast and, thus, facilitates the microscopy imaging of polymer samples. The history and important examples for this application are shown in the second half of the chapter.

Ru complexes might represent integral parts of a polymer—either within the backbone, the side chains or at the chain ends. Such polymers can be prepared via different synthetic routes, which have been adapted from conventional polymer science. The different synthetic strategies and types of Ru-containing polymers are discussed, taking also their characterization, properties and (potential) applications into account. In this respect, opto-electronics, photovoltaics, catalysis, and medicine have to be named as prominent areas of research.

The 3D metal–organic frameworks (MOFs) or 2D covalent organic frameworks (COFs) represent highly ordered, solid-state materials, which are employed in various fields of research. Hybrid materials in which Ru complexes or nanoparticles are caged or incorporated are discussed in the contexts of photovoltaics or catalysis. In particular, the energy-related applications (e.g., CO2 reduction of the hydrogen-evolution reaction) have emerged as central fields of research.

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. This huge metallo-tetrahedron with a molecular weight up to 70 000 Da was self-assembled simultaneously with 64 components: 12 large antler-shaped ligands (

Summary 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). These gigantic triangular assemblies are unambiguously confirmed by NMR, DOSY, ESI-MS, TWIM-MS, TEM, and AFM analyses. Notably, the dense-packed counterions of these discrete triangular architectures could further form supramolecular hydro-gels in water. This work not only provides a fundamental chemical pathway to explore various giant supramolecular constructs and further overcome the synthetic limitation of complicated molecular fractals, but also presents a new type of supramolecular hydro-gels with potential in controlled release applications., Graphical Abstract, Highlights • Giant supramacromolecular Sierpiński and Pascal's triangles • The design and use of small synthons to assemble high-order molecular fractals • A retro-assembly modular construction strategy for complicated molecular fractals • The dense-packed counterions of architectures could form supramolecular hydro-gels, Supramolecular Technologies; Supramolecular Materials; Molecular Self-Assembly; Materials Characterization Techniques

Planar, terpyridine-based metal complexes with the Sierpinski triangular motif and alkylated corners undergo a second self-assembly event to give megastructural Sierpinski 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.

Renewable organic batteries represent a valuable option to store sustainably generated energy and can play a major role in phasing out current carbon-based energy production. Several approaches have emerged over the last 80 years that utilize organic redox materials as active components in batteries. In particular, polymers have gained considerable interest among numerous research groups due to their (1) fast redox chemistry, in comparison to conventional active materials, (2) straight-forward syntheses, and (3) tunable solubility, which represent favored properties for diverse electronic devices. Notably, the beginning of redox-active polymers is linked to the discovery of conductive polymers by Heeger, MacDiarmid and Shirakawa in 1977. Nevertheless, redox-active polymers were studied in 1944 making them a familiar class under the broader polymeric framework, which celebrate its 100th birthday in 2020, based on the pioneering publication by Staudinger in 1920. Since their beginning, redox-active polymers have evolved from an interesting phenomenon into a family of promising, tailor-made, battery materials that also made their way to commercialization. In this regard, this review focusses on the design of interesting polymeric, redox-active materials. Polymerization techniques are discussed regarding novel polymer architectures and utilitarian properties. The polymer architectures are subsequently analyzed within the application scenarios of solid-state batteries, pseudo-capacitors, and redox-flow batteries. Redox moieties are compared and an overview of diverse synthetic aspects as well as battery concepts for the optimal assembly of polymeric battery materials are given.

The double- or triple-decker 3D metallo-hexagons were obtained by self-assembly of multitopic tris-terpyridines with Cd2+ 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 1 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. For the first time, the self-assembly of 45 units at once was demonstrated to yield exceptional giant triple-decker hexagons of up to circa 42 000 Da.

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.

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. New strategies have been employed to synthesize a range of 2D- and 3D-fractals as well as novel macrocyclic constructs by employing new designer strategies, such as: triangle-based frameworks, hexagonal fractal designs, flexible polyterpyridine linkers, and noncovalent interactions for spontaneous quantitative self-assembly. Numerous examples of heteroleptic self-assembly have been described along with the synthesis of heterometallic conjugates using step-wise protocols. Utilizing multiplanar, directed spacer units in the polyterpyridine vertices, new 3D-polyhedra were obtained facilitating the assembly of hybrid fractal-dendritic materials. These constructs are shown to undergo tunable conformational transformations by responding to specific stimuli such as concentration, temperature, and counter ions. The increasing ability to exploit hierarchical self-assembly of complex, higher order supramolecular nanomaterials is discussed.

The incorporation of metal complexes into polymers leads to functional materials; whereas, the properties of polymers – easy processability, light weight or the adjustable molar mass – and those of metal complexes – optical properties, catalytic activity or biomedical potential – can be combined. Through the years, various different applications have been developed, depending on the needs of current techniques and society. Thus, advanced applications enabled by metallopolymers, include areas: like self-assembly, stimuli-responsive behavior, catalysis, optics, self-healing, shape-memory as well as biomedicine and further potential applications can be expected. This review will summarize and discuss these applications as well as how the interactions of metal complexes and polymers enable them.

This overview describes our research progression from the study of heterocycle synthesis to dendritic architecture to simple metallomacrocycles, and finally to complex, fractal-based, suprametallomolecular materials. Construction of the first terpyridine-modified dendritic scaffold was followed by the construction and self-assembly of polyterpyridine monomers. Preparation of tristerpyridine building blocks used in concert with bisterpyridine analogs facilitated access to a Sierpinski gasket, as verified by direct visual observation with UHV-STEM, as well as other techniques. Numerous examples of heteroleptic self-assembly are described that include the quantitative preparation of a Sierpinski triangle. Addition of angled spacer moieties within polyterpyridine building blocks has generated a new family of 3D spherical materials that has facilitated the construction of hybrid fractal-dendritic materials that exhibit the unexpected concentration mediated, architectural transformations.

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 ZnII ions. The direct self-assembly of G2 and G3 triangles by mixing organic ligands and ZnII , however, only generated a mixture of G1 and G2, as well as a trace amount of insoluble polymer-like precipitate. Therefore, a modular strategy based on the connectivity of ⟨tpy-Ru2+ -tpy⟩ was employed to construct two metallo-organic ligands for the assembly of G2 and G3 Sierpinski triangles. The metallo-organic ligands LA and LB with multiple free terpyridines were obtained through Suzuki cross-coupling of the RuII complexes, and then assembled with ZnII or CdII to obtain high-generation metallo-triangular architectures in nearly quantitative yield. The G1-G3 architectures were characterized by NOESY and DOSY NMR spectroscopy, ESI-MS, TWIM-MS, and transmission electron microscopy.

A novel terpyridine-based, trapezoidal architecture was synthesized by a coordination-driven multicomponent assembly and features three different tpy-M2+-tpy bonds (M2+ = Ru2+, Fe2+, and Zn2+) 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.

A novel metallo-organic ligand [RuL2] with four uncomplexed coordination sites was created, and upon treatment with Zn2+ 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 Ru2+, two Fe2+, and two Zn2+ ions precisely located in the different edges. This strategy opens the door to novel designer 3D polymetallic constructs capable of diverse applications.

The design and construction of a novel terpyridine-based, dimetallic, 2D [4]triangulane architecture are reported. Synthesis of the metallotriangulane is achieved by multicomponent stepwise assembly of six bidentate and three tetradentate monomers. Characterization was accomplished by NMR spectroscopy, mass spectrometry and TEM microscopy.

A novel, tetrakisterpyridinyl-substituted porphyrin underwent self-assembly to form a three-dimensional, belt-shaped metallomacrocycle, which was characterized by 1D and 2D NMR and electrospray ionization traveling wave ion mobility mass spectrometry.

A series of coordination-driven, heteroleptic self-assembled, bowtie-shaped bis-macrocycles were designed and constructed by combining tetrakis(terpyridinyl)thianthrene and bis-terpyridine, 60°-directed, Ru2+ dimers. The resulting complexes were characterized by NMR spectroscopy and ESI-MS coupled with travelling wave ion mobility spectrometry (ESI-TWIM-MS) experiments. The desired bis-macrocycles were obtained in quantitative yields through the use of long alkyl-chain substituents, in contrast to the lower yields obtained for smaller alkyl moieties.

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. Each Au NC alone contained multiple nanoparticles, with diameters ranging from 2.5-4.5 nm. 1,4-bis-terpyridine based metallo-oraganic polymer [-TpyFeTpy-TpyFeTpy-]n(2n+) x [Cl]2n- 2 was found to generate a multi-ionic metallo-polymer with AuCl4- as the counterion, after mild reduction with sodium citrate, resulting in irregular zigzag shaped Au nanowires (Au NW). The prepared Au NW from the di-metallic complex 3 should find applications within electronic devices. Both Au NC and NW were also found to possess excellent catalytic properties.

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.

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. This opens a door to fabricate readily tailorable, large-scale, supramacromolecular materials.

Used individually or combinatorially, unique isocyanate-based dendritic monomers generate homo- and heterofunctional materials (the sketch shows schematically a molecule with a heterofunctional surface). Tier construction by combinatorial monomer addition offers new avenues to macromolecular architectural design and the control of physical properties.

The one-step synthesis of the first homoleptic metallomacrocycle is reported. Characterization of the OsII complex, along with its FeII and RuII analogues, was accomplished by NMR spectroscopy, ESI-MS, TWIM-MS, gradient tandem-MS, CV, luminescence and UV/Vis spectroscopy. Center-of-mass collision energies, derived from gradient tandem-MS, reveal that the -based structures are more stable than those of .

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). The mobility separated ions are subsequently identified by their mass-to-charge-ratios and isotope patterns in the orthogonal MS dimension. Finally, the gMS(2) dimension reveals bond breaking proclivities and disintegration pathways of the assemblies. The described methodology does not require high sample purity due to the dispersive nature of the IM and MS steps. Its utility is demonstrated with the comprehensive analysis of bisterpyridine-based metallomacrocycle mixtures and a tristerpyridine based complex with 3-D nanosphere-like architecture.

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. The unique properties of this new construct give rise to a dilution-based transformation into two identical spheres (octahedra) each possessing one half of the molecular weight of the parent structure; concentration of this octahedron reconstitutes the original cuboctahedron. These chemical phenomena are reminiscent of biological fission and fusion processes. The large 6 nm cage structure was further analyzed by 1D and 2D NMR spectroscopy, mass spectrometry, and collision cross-section analysis. New routes to molecular encapsulation can be envisioned.