A Highly Efficient Approach to the Self-Assembly of Hexagonal Cavity-Cored Tris[2]pseudorotaxanes from Several Components via Multiple Noncovalent Interactions

Yang, Hai Bo; Ghosh, Koushik; Northrop, Brian H.; Zheng, Yao‐Rong; Lyndon, Matthew M.; Muddiman, David C.; Stang, Peter J.

doi:10.1021/ja073744m

Cited by 117 publications

(47 citation statements)

References 25 publications

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“…SCCs typically display well-defined internal cavities with size and shape tunability, which provides the impetus for applications in host-guest chemistry [20][21][22] , catalysis 23 , molecular flasks 24 , supramolecular polymers [25][26][27] , bioengineering 28 and so on. Although quite a few metal complexes with attractive optical features are known 29,30 , light-emitting materials based on SCC platforms are relatively underdeveloped despite their prospects as advanced optical materials 31 .…”

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confidence: 99%

Highly emissive platinum(II) metallacages

et al. 2015

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Light-emitting materials, especially those with tunable wavelengths, attract considerable attention for applications in optoelectronic devices, fluorescent probes, sensors and so on. Many species evaluated for these purposes either emit as a dilute solution or on aggregation, with the former often self-quenching at high concentrations, and the latter falling dark when aggregation is disrupted. Here we preserve emissive behaviour at both low- and high-concentration regimes for two discrete supramolecular coordination complexes (SCCs). These tetragonal prismatic SCCs are self-assembled on mixing a metal acceptor, Pt(PEt3)2(OSO2CF3)2, with two organic donors, a pyridyl-decorated tetraphenylethylene and one of two benzene dicarboxylate species. The rigid organization of these fluorescence-active ligands imparts an emissive behaviour to dilute solutions of the resulting assemblies. Furthermore, on aggregation the prisms exhibit variable-wavelength visible-light emission, including rare white-light emission in tetrahydrofuran. The favourable photophysical properties and solvent-dependent aggregation behaviour provide a means to tune emission wavelengths.

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Highly emissive platinum(II) metallacages

et al. 2015

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“…So far, various SCCs with different geometries, such as 2D metallacycles (25)(26)(27)(28) and 3D metallacages (29)(30)(31)(32), were successfully prepared by the self-assembly of carefully selected metal acceptors and organic donors. Moreover, metal−ligand interactions show good tolerance of other noncovalent interactions such as hydrogen bonding and host−guest interactions, which were used to construct highly advanced functional supramolecular entities, such as mechanically interlocked molecules (33)(34)(35) and supramolecular polymers (36)(37)(38), via orthogonal self-assembly.…”

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confidence: 99%

“…Although some progress has been made on the functionalization of metallacycles to construct stimuli-responsive supramolecular complexes and polymers (33)(34)(35)(36)(37)(38), the covalent linkage (39-41) of metallacycles to synthesize functional polymers has rarely been reported. The main difficulty of this strategy lies in how to maintain the dynamic metallacycle structures during the linking process.…”

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Fluorescent metallacycle-cored polymers via covalent linkage and their use as contrast agents for cell imaging

Zhang

Shu-ya

Yan

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The covalent linkage of supramolecular monomers provides a powerful strategy for constructing dynamic polymeric materials whose properties can be readily tuned either by the selection of monomers or the choice of functional linkers. In this strategy, the stabilities of the supramolecular monomers and the reactions used to link the monomers are crucial because such monomers are normally dynamic and can disassemble during the linking process, leading to mixture of products. Therefore, although noncovalent interactions have been widely introduced into metallacycle structures to prepare metallosupramolecular polymers, metallacyclecored polymers linked by covalent bonds have been rarely reported. Herein, we used the mild, highly efficient amidation reaction between alkylamine and N-hydroxysuccinimide-activated carboxylic acid to link the pendent amino functional groups of a rhomboidal metallacycle 10 to give metallacycle-cored polymers P1 and P2, which further yielded nanoparticles at low concentration and transformed into network structures as the concentration increased. Moreover, these polymers exhibited enhanced emission and showed better quantum yields than metallacycle 10 in methanol and methanol/water (1/9, vol/vol) due to the aggregationinduced emission properties of a tetraphenylethene-based pyridyl donor, which serves as a precursor for metallacycle 10. The fluorescence properties of these polymers were further used in cell imaging, and they showed a significant enrichment in lung cells after i.v. injection. Considering the anticancer activity of rhomboidal Pt(II) metallacycles, this type of fluorescent metallacycle-cored polymers can have potential applications toward lung cancer treatment.fluorescent polymers | supramolecular coordination complex | covalent linkage | aggregation-induced emission | cell imaging F luorescent polymers have received much attention in the chemical and life sciences due to their promising applications in biological labeling, tracking, monitoring, imaging, and diagnostics (1-3). Compared with other fluorophores such as small molecules and quantum dots, they are advantageous as biomaterials because of their good biocompatibility, ease of preparation, and biomimetic character (4-6). Conventional fluorophores show good emission in dilute solution but experience varying degrees of aggregation-caused quenching due to the intense intermolecular interactions, which will decay or relax the excited state back to the ground state via nonradiative channels (7). Such fluorophores are not ideal candidates for the preparation of fluorescent polymers, because they need to be aggregated by the polymerization process, which will more or less decrease the fluorescence emissions and the quantum yields of the derived fluorescent polymers.In 2001, Tang and coworkers (8) reported an opposite fluorescence effect named as aggregation-induced emission (AIE). In such cases, fluorophores are nearly nonemissive as discrete molecules, but they exhibit strong fluorescence in concentrated solution or in the s...

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“…This approach organizes metal acceptors and organic donors to prepare well-defined cavity-cored 2D metallacycles and 3D metallacages, which can be functionalized on their interior or exterior vertices for applications in host-guest chemistry (21,22), catalysis (23), molecular flasks (24), bioengineering (25), amphiphilic self-assembly (26), and so on. The versatility of coordination-driven self-assembly can be enhanced by designs that allow for post-self-assembly modifications that in some cases result in complete structural transformations.…”

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Photoinduced transformations of stiff-stilbene-based discrete metallacycles to metallosupramolecular polymers

Yan

Jiang

Cook

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Control over structural transformations in supramolecular entities by external stimuli is critical for the development of adaptable and functional soft materials. Herein, we have designed and synthesized a dipyridyl donor containing a central Z-configured stiff-stilbene unit that self-assembles in the presence of two 180°di-Pt(II) acceptors to produce size-controllable discrete organoplatinum(II) metallacycles with high efficiency by means of the directionalbonding approach. These discrete metallacycles undergo transformation into extended metallosupramolecular polymers upon the conformational switching of the dipyridyl ligand from Z-configured (0°) to E-configured (180°) when photoirradiated. This transformation is accompanied by interesting morphological changes at nanoscopic length scales. The discrete metallacycles aggregate to spherical nanoparticles that evolve into long nanofibers upon polymer formation. These fibers can be reversibly converted to cyclic oligomers by changing the wavelength of irradiation, which reintroduces Z-configured building blocks owing to the reversible nature of stiff-stilbene photoisomerization. The design strategy defined here represents a novel self-assembly pathway to deliver advanced supramolecular assemblies by means of photocontrol.metal coordination | supramolecular coordination complex | photoirradiation | reversibility | dynamic materials N atural systems provide many examples of self-assembled biosupramolecules that respond to external stimuli through conformational changes that ultimately play a role in carrying out their various biological functions. Mimicking this stimuli-responsive behavior in artificial systems is a promising route toward obtaining sophisticated molecular-based architectures with functional and structural tunability (1-3). Using the absorption of photons as a trigger is particularly attractive in that light-induced transformations maintain high spatial and temporal resolution without producing waste products even during multiple reversible switching sequences (4). In materials science, one of the most appealing characteristics of photochromic molecules is the direct conversion of light into mechanical energy based on their photo-reversible structural transformations (5). Among such chromophores, a stiffstilbene moiety (1,1′-biindane) is useful owing to its unique characteristics (6). First, stiff stilbene can adopt either a cis or trans configuration with respect to its central double bond. Second, the high activation barrier between the two isomers (∼43 kcal·mol −1 , corresponding to a half-life of ∼10 9 y at 300 K) makes thermal E/Z isomerization negligible at temperatures of 420 K and lower. Third, the quantum yield for the photoisomerization of either isomer is high (50%). Fourth, the stiff-stilbene core is readily substituted using well-established synthetic methods. Owing to these promising characteristics, Boulatov and coworkers (7) constructed a molecular force probe by integrating the moiety into a stretched polymer to mimic the strain gen...

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A Highly Efficient Approach to the Self-Assembly of Hexagonal Cavity-Cored Tris[2]pseudorotaxanes from Several Components via Multiple Noncovalent Interactions

Cited by 117 publications

References 25 publications

Highly emissive platinum(II) metallacages

Highly emissive platinum(II) metallacages

Fluorescent metallacycle-cored polymers via covalent linkage and their use as contrast agents for cell imaging

Photoinduced transformations of stiff-stilbene-based discrete metallacycles to metallosupramolecular polymers

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