Tunable Visible Light Emission of Self-Assembled Rhomboidal Metallacycles

Pollock, J. Bryant; Schneider, Gregory L.; Cook, Timothy R.; Davies, Andrew; Stang, Peter J.

doi:10.1021/ja4079607

Cited by 70 publications

(53 citation statements)

References 63 publications

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“…A similar reaction of 1,6-bis(pyrid-4-ylethynyl) 3-methylaniline 2 and 2,9-bis[transPt(PEt 3 ) 2 NO 3 ] phenanthrene 3 gave SCC 5. Both SCCs were found to have low energy absorption and emission band maxima in dichloromethane (Table 1) (40). The low energy absorption and emission band maxima of ligand 1 were blue shifted compared with those of 4 by 57 nm (3,554 cm…”

Section: Resultsmentioning

confidence: 99%

“…been developed that display different photophysical properties from those of their constituent subunits (40). These assemblies are interesting targets to investigate the cytotoxicity of organoplatinum SCCs, whereas their emission spectra could be used for interrogating the structural integrity in vitro.…”

Section: Significancementioning

confidence: 99%

“…Moreover, recent reports have demonstrated that platinum-based SCCs can act as effective hosts for guests and have interesting photophysical properties (37)(38)(39)(40)(41)(42). In particular, highly emissive rhomboids based on aniline-containing donors and Pt-based metal acceptors have…”

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confidence: 99%

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In vivo anticancer activity of rhomboidal Pt(II) metallacycles

Grishagin

Pollock

Kushal

et al. 2014

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

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101

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The development of novel antitumor agents that have high efficacy in suppressing tumor growth, have low toxicity to nontumor tissues, and exhibit rapid localization in the targeted tumor sites is an ongoing avenue of research at the interface of chemistry, cancer biology, and pharmacology. Supramolecular metal-based coordination complexes (SCCs) have well-defined shapes and geometries, and upon their internalization, SCCs could affect multiple oncogenic signaling pathways in cells and tissues. We investigated the uptake, intracellular localization, and antitumor activity of two rhomboidal Pt(II)-based SCCs. Laser-scanning confocal microscopy in A549 and HeLa cells was used to determine the uptake and localization of the assemblies within cells and their effect on tumor growth was investigated in mouse s.c. tumor xenograft models. The SCCs are soluble in cell culture media within the entire range of studied concentrations (1 nM-5 μM), are nontoxic, and showed efficacy in reducing the rate of tumor growth in s.c. mouse tumor xenografts. These properties reveal the potential of Pt(II)-based SCCs for future biomedical applications as therapeutic agents. supramolecular coordination complexes | fluorescence | cell culture | tumor growth | xenografts M olecular assemblies of nanoscale-size and well-defined geometries have recently emerged as an interesting new paradigm in drug design and drug delivery. To date, liposomes, the self-assembled lipid nanoparticles held together by weak interactions, are among the most widely studied and clinically successful nanoparticle-based drug carriers. Their use allows the drug to achieve sustained plasma levels while encapsulated, with the size preventing the fast clearance by the kidneys that often occurs with the free drug. However, liposomes themselves do not produce a therapeutic effect and their application as drug carriers for medical purposes has often been hindered by poor loading capacity (<5 wt %) and the inability to pass through biological barriers (1, 2). Inorganic and hybrid porous materials, such as molecular organic frameworks (MOFs), have also shown promise due to their higher loading capacities (>25 wt %) (3-5), but MOFs have poor hydrolytic stability (6, 7). Recent studies on materials from Institut Lavoisier (MIL)-100(Cr) and MIL-100(Fe), however, suggest that MOFs can persist in biologically relevant environments and can act as vehicles for some anticancer and antiviral agents (8-10). These early findings have prompted further investigations into the biomedical applications of supramolecular coordination complexes (SCCs) (11-24). SCCs preserve the attractive properties of MOFs, such as building block modularity (22,23,25), yet afford an increased solubility in the biological milieu and lend themselves to small-molecule characterization techniques due to their well-defined structure.Although development of SCCs for biomedical applications is in its infancy, some SCCs, such as trigonal prisms self-assembled from p-cymene and ruthenium-based metal fragments with py...

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Section: Resultsmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

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In vivo anticancer activity of rhomboidal Pt(II) metallacycles

Grishagin

Pollock

Kushal

et al. 2014

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

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101

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“…Due to the directionality of metal−ligand bonds and their moderate bond energies, the structures of SCCs can be finely tuned. 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%

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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113

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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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“…The inherent stability and rather low reactivity of the Pt(II) in contrast with other metals [i.e., Pd(II)] [40,41] has been the main attraction for the use of Pt(II) units for metallamacrocycles [42]. Furthermore, the attractive photophysical properties of Pt(II) complexes, such as low-energy, tunability and long-lived excited states, have prompted their incorporation into metallacycles [43][44][45][46][47]. The combination of the luminescent Pt(II) units in the corners with luminophore N-groups that can act as linkers can be exploited in highly emissive metallacycles [48].…”

Section: Introductionmentioning

confidence: 99%