CUED Publications database

Threading the Needle: Fluorescent Poly-pseudo-rotaxanes for Size-Exclusion Sensing

Willis-Fox, N and Belger, C and Fennell, JF and Evans, RC and Swager, TM (2016) Threading the Needle: Fluorescent Poly-pseudo-rotaxanes for Size-Exclusion Sensing. Chemistry of Materials, 28. pp. 2685-2691. ISSN 0897-4756

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Abstract

© 2016 American Chemical Society. Poly-pseudo-rotaxanes have been formed through the threading of cucurbit[n]urils (CB[n] ) onto the cationic electron-poor poly(pyridyl vinylene), PPyV. The threading of CB[n] onto the PPyV backbone is confirmed by a broadening and upfield shift in the PPyV 1 H NMR signals. Encapsulation of PPyV within the CB[n] macrocycles produces dramatic fluorescence enhancements with improved solubility. The threading ability of the CB[n] on the PPyV backbone is governed by the dimensions of the particular CB[n] portal, which grows with increasing number of methylene-bridged glycoluril repeat units. CB[5] is too small to thread onto the PPyV backbone. The portal of CB[6] requires extra time, suggesting high preorganization and/or macrocycle deformation are required to thread onto PPyV. Alternatively, the portal of CB[8] appears to be large enough such that it does not have sufficiently large dipole-dipole interactions with the PPyV chain to promote a strong threading equilibrium. However, we find that the portal of CB[7] is optimal for the threading of PPyV. The PPyV-CB[n] system was further exploited to demonstrate a dual-action sensor platform, combining the PL-responsive behavior demonstrated by PPyV toward electron-rich analytes with the size-exclusion properties imparted by volume of the respective CB[n] cavities. Thin films of PPyV-CB[7] were found to display reversible photoluminescence quenching when exposed to vapors of the biologically relevant molecule indole, which is recovered under ambient conditions, suggesting prospects for new size-exclusion based selective sensory schemes for volatile electron-rich analytes.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div E > Production Processes
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:39
Last Modified: 21 Nov 2017 03:17
DOI: