Guest Recognition Control Accompanied by Stepwise Gate Closing and Opening of a Macrocyclic Metallohost.

Authors :: Sakata Y
Okada M
Akine S
Source :: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2021 Feb 01; Vol. 27 (7), pp. 2284-2288. Date of Electronic Publication: 2020 Nov 18.
Publication Year :: 2021
Abstract: Host-guest binding behavior of macrocyclic hosts is significantly influenced by the shapes and sizes of the hosts. In particular, closing/opening the apertures of the hosts controls the guest uptake/release. A post-metalation modification method was used to achieve the open/close conversions. The starting open complex, [LCo <subscript>2</subscript> (pip) <subscript>4</subscript> ](OTf) <subscript>2</subscript> , was efficiently converted to the closed complex, [LCo <subscript>2</subscript> (hda) <subscript>2</subscript> ](OTf) <subscript>2</subscript> , which has a doubly bridged structure. The conversion of this closed complex to the open complex [LCo <subscript>2</subscript> (hda) <subscript>2</subscript> (OAc)] <superscript>+</superscript> was too slow to be completed, but this gate-opening was dramatically accelerated by the addition of Na <superscript>+</superscript> . The Na <superscript>+</superscript> binding was also significantly enhanced by the gate-opening, that is, conversion of [LCo <subscript>2</subscript> (hda) <subscript>2</subscript> ] <superscript>2+</superscript> to [LCo <subscript>2</subscript> (hda) <subscript>2</subscript> (OAc)] <superscript>+</superscript> .<br /> (© 2020 Wiley-VCH GmbH.)

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