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Unraveling the Structure-Affinity Relationship between Cucurbit[n]urils (n=7, 8) and Cationic Diamondoids
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SYSNO ASEP 0475010 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Unraveling the Structure-Affinity Relationship between Cucurbit[n]urils (n=7, 8) and Cationic Diamondoids Author(s) Sigwalt, D. (US)
Šekutor, M. (HR)
Cao, L. (US)
Zavalij, P. Y. (US)
Hostaš, Jiří (UOCHB-X) RID
Ajani, Haresh (UOCHB-X) ORCID, RID
Hobza, Pavel (UOCHB-X) RID, ORCID
Mlinaric-Majerski, K. (HR)
Glaser, R. (IL)
Isaacs, L. (US)Source Title Journal of the American Chemical Society. - : American Chemical Society - ISSN 0002-7863
Roč. 139, č. 8 (2017), s. 3249-3258Number of pages 10 s. Language eng - English Country US - United States Keywords host-guest complexation ; high-energy water ; driving force Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GBP208/12/G016 GA ČR - Czech Science Foundation (CSF) Institutional support UOCHB-X - RVO:61388963 UT WOS 000395493400059 EID SCOPUS 85014288032 DOI 10.1021/jacs.7b00056 Annotation We report the measurement of the binding constants (K-a) for cucurbit[n]uril (n = 7, 8) toward four series of guests based on 2,6-disubstituted adamantanes, 4,9-disubstituted diamantanes, 1,6-disubstituted diamantanes, and 1-substituted adamantane ammonium ions by direct and competitive H-1 NMR spectroscopy. Compared to the affinity of CB[7]Diam(NMe3)(2), the adamantane diammonium ion complexes (e.g., CB[7]2,6-Ad(NH3)(2) and CB[7]2,6-Ad(NMe3)(2)) are less effective at realizing the potential 1000-fold enhancement in affinity due to ion-dipole interactions at the second ureidyl C=O portal. Comparative crystallographic investigation of CB[7]Diam(NMe3)(2), CB[7]DiamNMe(3), and CB[7]1-AdNMe(3) revealed that the preferred geometry positions the +NMe3 groups approximate to 0.32 above the C=O portal, the observed 0.80 spacing observed for CB[7]Diam(NMe3)(2) reflects the simultaneous geometrical constraints of CH2O=C close contacts at both portals. Remarkably, the CB[8]IsoDiam(NHMe2)2 complex displays femtomolar binding affinity, placing it firmly alongside the CB[7]Diam(NMe3)(2) complex. Primary or quaternary ammonium ion looping strategies lead to larger increases in binding affinity for CB[8] than for CB[7], which we attribute to the larger size of the carbonyl portals of CB[8], this suggests routes to develop CB[8] as the tightest binding host in the CB[n] family. We report that alkyl group fluorination (e.g., CB[7]1-AdNH(2)Et versus CB[7]1-AdNH(2)CH(2)CF(3)) does not result in the expected increase in Ka value. Finally, we discuss the role of solvation in nonempirical quantum mechanical computational methodology, which is used to estimate the relative changes in Gibbs binding free energies. Workplace Institute of Organic Chemistry and Biochemistry Contact asep@uochb.cas.cz ; Kateřina Šperková, Tel.: 232 002 584 ; Jana Procházková, Tel.: 220 183 418 Year of Publishing 2018
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