- A Dynamic Hydrogen-Bonded Azo-Macrocycle for Precisely Photo-Controlled Molecular Encapsulation and Release
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A light-responsive system constructed from hydrogen-bonded azo-macrocycles demonstrates precisely controlled propensity in molecular encapsulation and release process. A significant decrease in the size of the cavity is observed in the course of the E→Z photoisomerization based on the results from DFT calculations and traveling wave ion mobility mass spectrometry. These macrocyclic hosts exhibit a rare 2:1 host–guest stoichiometry and guest-dependent slow or fast exchange on the NMR timescale. With the slow host–guest exchange and switchable shape change of the cavity, quantitative release and capture of bipyridinium guests is achieved with the maximum release of 68 %. This work underscores the importance of slow host–guest exchange on realizing accurate release of organic cations in a stepwise manner under light irradiation. The light-responsive system established here could advance further design of novel photoresponsive molecular switches and mechanically interlocked molecules.
- Ye, Zecong,Yang, Zhiyao,Wang, Lei,Chen, Lixi,Cai, Yimin,Deng, Pengchi,Feng, Wen,Li, Xiaopeng,Yuan, Lihua
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- Sequence-specific association in aqueous media by integrating hydrogen bonding and dynamic covalent interactions
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Oligoamide strands that associate in a sequence-specific fashion into hydrogen-bonded duplexes in nonpolar solvents were converted into disulfide cross-linked duplexes in aqueous media. Thus, by incorporating trityl-protected thiol groups, which allows the reversible formation of disulfide bonds, into the oligoamide strands, only duplexes consisting of complementary hydrogen-bonding sequences were formed in aqueous solution as well as in methanol. The sequence-specific cross-linking of oligoamide strands was confirmed by MALDI-TOF, reverse-phase HPLC, and by isolating a cross-linked duplex. This study demonstrates that the sequence-specificity characteristic of multiply hydrogen-bonded systems can be extended into competitive media through the interplay of H-bonding and reversible covalent interactions, based on which a new class of molecular associating and ligating units that are compatible with both polar and nonpolar environments can be conveniently obtained. Copyright
- Li, Minfeng,Yamato, Kazuhiro,Ferguson, Joseph S.,Gong, Bing
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p. 12628 - 12629
(2008/02/05)
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