A Light‐Driven Pseudo[4]rotaxane Encoded by Induced Circular Dichroism in a Hydrogel

Abstract

A light‐driven pseudo[4]rotaxane 1, based on α‐cyclodextrin (α‐CyD) and cucurbit[7]uril (CB[7]), is prepared in an easy and convenient manner. The reference pseudo[2]rotaxane 2 and pseudo[3]rotaxane 2′ are obtained via the insertion of α‐CyD and CB[7] onto the dumbbell 3, thus including an azobenzene unit and two viologen moieties, respectively. The CyD macrocycle in pseudo[4]rotaxane 1 can be photochemically stimulated to shuttle accompanied with obvious induced circular dichroism (ICD) signals. The ICD performances of these pseudorotaxanes, including ICD in aqueous solution, variable‐temperature ICD, ICD in confected hydrogel systems and in solid‐state films, are investigated for their conformational identification. The photo‐driven shuttling of the CyD macrocycle in pseudo[4]rotaxane 1 is easier than in the CyD‐based pseudo[2]rotaxane 2, especially in non‐solution media. This can be attributed to the space exploitation of CB[7]‐included parts, which aid the movement of α‐CyD.

A Rapidly Self‐Healing Supramolecular Polymer Hydrogel with Photostimulated Room‐Temperature Phosphorescence Responsiveness

“…The azobenzene group was known to be included by b-CD to generate ICD signal. [32] As shown in Figure 3 c, a positive Cotton peak at about 303 nm and a negative Cotton peak at around 437 nm appeared after mixing the three polymers together at a ratio of 1:10:2.5, which were attributed to the p-p* and n-p* transition bands respectively of azobenzene groups of poly-Azo in trans conformation located within b-CD cavities of poly-b-CD. [16] The prolonged irradiation with 365 nm light to this ternary system brought about a gradual intensity increase of both the two Cotton peaks shown in Figure 3 c (curves a, b, and c).…”

β-Cyclodextrin/Azobenzene Microspheres Loaded with Paraquat Are Safe and Effective

“…UV−Vis Spectrum and Circular Dichroism Spectra Analysis. According to the study by Ma et al, 32 the chiral induction of CD caused β-CD to induce azobenzene to produce a clearly inducible circular dichroism signal when the trans-azo group was incorporated into the cavities of β-CD via host−guest complexation. Furthermore, the trans-azo group exhibited a distinct absorption peak position, as shown in Figure 3a: the absorbance at 348 nm.…”

A facile way to obtain near-infrared room-temperature phosphorescent soft materials based on Bodipy dyes

“…Since articial so materials like supramolecular gels are receiving wide attention, 55,56 self-healable NIR RTP emitting gels were facilely prepared with the incorporation of UPy and MBAA into p-1IBDP and p-2IBDP. MBAA acts as a crosslinker.…”