Reversible photo-responsive gel–sol transitions of robust organogels based on an azobenzene-containing main-chain liquid crystalline polymer

Abstract

A robust and photo-responsive organogel has been constructed by introducing an azobenzene-containing main-chain liquid crystalline polymer gelator.

Excited State Charge Separation in an Azobenzene‐Bridged Perylenediimide Dimer – Effect of Photochemical Trans‐Cis Isomerization

“…PDI‐dimer was synthesized for the first time according to Scheme 1 by a fluoride‐assisted nucleophilic substitution on a halogenated PDI, a procedure previously developed by us. [6] Thus, reaction of 1‐bromoPDI [7] with 4,4’‐dihydroxyazobenzene [8] in the presence of caesium fluoride and 18‐crown‐6 afforded the azo‐bridged dimer in 46 % yield. PDI‐control 1 and PDI‐control 2 were prepared using the same methodology.…”

“…4,4’‐bis[ N,N’ ‐di(hexylheptyl)perylene‐3’’,4’’:9’’,10’’‐tetracarboxidiimide‐1’’‐yloxy]azobenzene (PDI Dimer) : 4,4’‐dihydroxyazobenzene [8] (22 mg, 0.1 mmol), 18‐crown‐6 (1.06 g, 4 mmol) and CsF (152 mg, 1 mmol) were added to a solution of N , N’ ‐di(hexylheptyl)‐1‐bromo‐3,4 : 9,10‐perylenetetracarboxydiimide, [7] Br‐PDI, (208 mg, 0.25 mmol) in dry THF (3 mL). The reaction was refluxed 24 h under argon atmosphere and, after cooling, it was extracted with dichloromethane and washed with water.…”

Wholly Visible-Light-Responsive Host–Guest Supramolecular Gels Based on Methoxy Azobenzene and β-Cyclodextrin Dimers

“…When the binary gelator concentration is higher than 7 wt %, G′ is more than 10 4 Pa, which suggests that the gels show good selfsupporting ability. 13,32,33,35,61,62 Formation Mechanism of the mAzo Dimer/β-CD Dimer Supramolecular Gels. The interior morphological structure of the supramolecular gel was studied by FE-SEM (SEM).…”

Photodeformable Azobenzene-Containing Polyimide with Flexible Linkers and Molecular Alignment

“…The intensity changes of π → π* and n → π* transitions suggest that both DAC3AB-PI and DAAB-PI undergo trans−cis isomerization under UV light irradiation. Remarkably, DAC3AB-PI undergoes faster isomerization, as the time required for reaching the photosationary state (PSS) of DAC3AB-PI and DAAB-PI was 8 and 120 s, respectively.To quantify the trans−cis isomerization rates of the azo-PIs, the first-order kinetic coefficient k tc about the photochemical isomerization was introduced and calculated via time-resolved UV−vis absorption spectra as the following equation:38,39…”

“…Remarkably, DAC3AB-PI undergoes faster isomerization, as the time required for reaching the photosationary state (PSS) of DAC3AB-PI and DAAB-PI was 8 and 120 s, respectively. To quantify the trans–cis isomerization rates of the azo-PIs, the first-order kinetic coefficient k tc about the photochemical isomerization was introduced and calculated via time-resolved UV–vis absorption spectra as the following equation: , where A 0 , A t , and A ∞ are the absorbance values before irradiation, after irradiation for t , and at the photostationary state, respectively. According to the linear fitting (Figure c,d), the k tc for DAC3AB-PI and DAAB-PI in NMP solution are calculated as 0.35 and 0.023 s –1 , respectively.…”