Control of Photoisomerization of an Azoazacryptand by Anion Binding and Cucurbit[8]uril Encapsulation in an Aqueous Solution

Control of isomerization of a receptor bearing multiple light-switchable subunits in a confined space is critical for the design of synthetic molecular machines. Toward this goal, a new azacryptand containing three azobenzene subunits has been developed, and its photoisomerization in an aqueous solution has been studied depending on anion coordination and recognition by a larger host - cucurbit[8]uril (CB[8]). The cryptand in its hexaprotonated form shows considerable affinity for fluoride and perchlorate, which in turn affects the isomer distribution of the receptor under UV-light irradiation, stabilizing the isomers of the cryptand with Z-configurations. CB[8] was found to be able to encapsulate the isomers of the cryptand by forming a Matryoshka-type complex. The irradiation of a 10:1 CB[8]-cryptand mixture has led to a selective conversion of the cryptand to the E,E,Z isomer inside CB[8]. It has been demonstrated that the addition of fluoride to the resulted complex induces the release of the cryptand as a major E,E,E isomer, while other studied anions were ineffective in this reaction. To our knowledge, this work presents a first example of a host-controlled photoisomerization of an anion receptor bearing multiple switching azobenzenes that model the function of naturally occurring chaperones. Copyright © 2020 American Chemical Society.

Oshchepkov A.S. 1 , Namashivaya S.S.R.1 , Khrustalev V.N. 2 , Hampel F.3 , Laikov D.N.4 , Kataev E.A.3
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  • 1 Faculty of Natural Sciences, Technische Universität Chemnitz, Chemnitz, 09107, Germany
  • 2 Peoples' Friendship University of Russia (RUDN University), Moscow, 117198, Russian Federation
  • 3 Department of Chemistry and Pharmacy, University Erlangen-Nürnberg, Nikolaus-Fiebiger-Str. 10, Erlangen, 91058, Germany
  • 4 Chemistry Department, Moscow State University, Leninskie Gory, GSP-1, Moscow, 119991, Russian Federation
Ключевые слова
Azobenzene; Bearings (machine parts); Fluorine compounds; Inorganic compounds; Irradiation; Negative ions; Plants (botany); Anion coordination; Confined space; Cucurbit[8]uril; Isomer distributions; Molecular machines; Multiple switching; Naturally occurring; UV-light irradiation; Isomers; anion; azobenzene; chloroform; cryptand; cyclodextrin; fluoride; macrocyclic compound; nitrate; perchlorate; aqueous solution; Article; association constant; chemical binding; chemical structure; conformational transition; controlled study; dipole; electrospray mass spectrometry; encapsulation; hydrogen bond; hydrophilicity; hydrophobicity; isomer; isomerization; mass spectrometry; pH; potentiometric titration; proton nuclear magnetic resonance; protonation; solubilization; stereoisomerism; stoichiometry; structure analysis; trans isomer; ultraviolet radiation; X ray analysis
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