- Diverse Proton-Conducting Nanotubes via a Tandem Macrocyclization and Assembly Strategy
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Macrocycles that assemble into nanotubes exhibit emergent properties stemming from their low dimensionality, structural regularity, and distinct interior environments. We report a versatile strategy to synthesize diverse nanotube structures in a single, efficient reaction by using a conserved building block bearing a pyridine ring. Imine condensation of a 2,4,6-triphenylpyridine-based diamine with various aromatic dialdehydes yields chemically distinct pentagonal [5 + 5], hexagonal [3 + 3], and diamond-shaped [2 + 2] macrocycles depending on the substitution pattern of the aromatic dialdehyde monomer. Atomic force microscopy and in solvo X-ray diffraction demonstrate that protonation of the macrocycles under the mild conditions used for their synthesis drives assembly into high-aspect ratio nanotubes. Each of the pyridine-containing nanotube assemblies exhibited measurable proton conductivity by electrochemical impedance spectroscopy, with values as high as 10-3 S m-1 (90% R.H., 25 °C) that we attribute to differences in their internal pore sizes. This synthetic strategy represents a general method to access robust nanotube assemblies from a universal pyridine-containing monomer, which will enable systematic investigations of their emergent properties.
- Strauss, Michael J.,Jia, Manping,Evans, Austin M.,Castano, Ioannina,Li, Rebecca L.,Aguilar-Enriquez, Xavier,Roesner, Emily K.,Swartz, Jeremy L.,Chavez, Anton D.,Enciso, Alan E.,Stoddart, J. Fraser,Rolandi, Marco,Dichtel, William R.
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- Hexagon wreaths: Self-assembly of discrete supramolecular fractal architectures using multitopic terpyridine ligands
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In this study, we overcame a challenge in conventional self-assembly of macrocycles that uses ditopic 2,2:6,2-terpyridine (tpy) building blocks with a 120angle between two ligating moieties, which generally produces a mixture of multiple macrocycles instead of a single hexagon. Two supramolecular hexagon wreaths, [Zn9LA6] and [Zn12LB6], were designed and self-assembled from tritopic and tetratopic tpy ligands with Zn(II) ions, respectively. These multitopic ligands, bearing multiple binding sites, increased the total density of coordination sites and provided high geometric constraints to induce the formation of discrete structures. Such hexagon wreaths, which were constructed by simple recursion of small hexagons around a central hexagon, exhibit fractal geometry features with self-similarity at different levels. The shapes, sizes, and structures were fully characterized by NMR, ESI-MS, traveling-wave ion mobility mass spectrometry (TWIM-MS), and transmission electron microscopy. With diameters around 5.5 nm for [Zn 9LA6] and 5.8 nm for [Zn12LB6], the remarkable rigidity of these fractal architectures was supported by TWIM-MS, in contrast to the high flexibility of macrocycles assembled by ditopic tpy ligands.
- Wang, Ming,Li, Xiaopeng,Wang, Chao,Hao, Xin-Qi,Liu, Jingjing,Li, Xiaohong,Xu, Chenglong,Lopez, Alberto,Sun, Luyi,Song, Mao-Ping,Yang, Hai-Bo
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p. 6664 - 6671
(2014/05/20)
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- Towards a better understanding of the magnetic interactions within m-phenylene α-nitronyl imino nitroxide based biradicals
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An extensive investigation of the magnetic properties of three series of biradicals (bis-nitronyl nitroxides diNN-R, bis-imino nitroxides diIN-R and mixed INNN-R, where R is either hydrogen, a triple bond or trimethylsilylacetylenic group) has been carrie
- Catala, Laure,Le Moigne, Jacques,Kyritsakas, Nathalie,Rey, Paul,Novoa, Juan J.,Turek, Philippe
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p. 2466 - 2480
(2007/10/03)
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- Synthesis of nitronyl- and imino-nitroxide-triradicals interconnected by phenyl ethynyl spacer
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The design and synthesis, as well as solid state and ESR characterisation of three new triradicals based on phenyl ethynyl backbone bearing nitronyl-nitroxide and imino-nitroxide groups, are reported. The synthesis of these compounds was based on palladium-coupling reactions between alkynyl and bromo derivatives. An ESR study showed magnetic interactions between the radicals through the phenyl ethynyl-coupling unit in solution. (C) 2000 Elsevier Science Ltd.
- Catala, Laure,Turek, Philippe,Le Moigne, Jacques,De Cian, André,Kyritsakas, Nathalie
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p. 1015 - 1018
(2007/10/03)
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