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

Abstract

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 Matryoshkatype 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.

Light-Powered Dissipative Assembly of Diazocine Coordination Cages

“… 5 − 12 Among various stimuli (e.g., pH, 13 − 15 temperature, 16 solvent, 17 electrochemical, 18 , 19 or chemical input 20 , 21 ), light is a highly advantageous reagent, as it can be precisely administered with temporal and spatial resolution, is available from cheap LED sources, and is essentially waste-free. The light-triggered modification of structure and function of (supra)molecular systems can be achieved using dedicated photoswitches such as azobenzenes, 22 , 23 dithienylethenes, 24 , 25 other hindered alkenes, 26 , 27 indigoids, 28 and spiropiranes, 29 , 30 just to name a few. At the same time, light can be used as a fuel to drive systems away from thermal equilibrium, generating dissipative self-assembled systems.…”

Host‐Guest Assemblies of Cyanostilbenes and Cucurbit[8]uril: Luminescence Modulation, Photoreactivity Control and Energy Transfer Studies

“…Control of photoisomerization of an azoazacryptand by employing CB[8] has been reported by Kataev et. al [23c] . Moreover, photodimerization of anthracene derivative by Scherman et.…”

The Colorimetric Sensor Based on Azobenzenes with Sulfonamide Group for Fluorine Ion and Moisture Detection in Organic Solvents

“…Azo dyes are the most important commercial organic colorant in treating textiles, indicators, food additives and so on [1,2] . Due to the tunable properties of absorption, dispersion, and response to light and temperature, azo dyes and relatives have been used in conductive materials, [3] optical storage media, [4,5] chemosensors, [5,6] energy storage, [7] electrocatalyst and molecular photoswitch [8–20] . The color of azo dyes depends on the intrinsic structure of itself.…”

“…[1,2] Due to the tunable properties of absorption, dispersion, and response to light and temperature, azo dyes and relatives have been used in conductive materials, [3] optical storage media, [4,5] chemosensors, [5,6] energy storage, [7] electrocatalyst and molecular photoswitch. [8][9][10][11][12][13][14][15][16][17][18][19][20] The color of azo dyes depends on the intrinsic structure of itself. For instance, the number of azo group and the species and number of auxochromic group containing electron-donating and electron-withdrawing groups, take azo dyes different coloring effect, such as hyperchromic, hypochromic, hypsochromic and bathochromic effect (Scheme 1).…”