Deciphering Internal and External π‐Conjugation in C₃‐Symmetric Multiple Azobenzene Connected Systems in Self‐Assembly

Abstract

Two tripodal C 3 -symmetric photoswitchable molecular systems T1 and T2 are reported that have extended conjugation at external and internal positions using an acryl group. The influence of the extended π-bonds in their absorption properties, thermal relaxation of the photoisomers and their propensities in forming supramolecular self-assemblies have been explored through spectroscopy, and microscopic studies. In particular, the investigations on the self-assembly have been carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), polarized optical microscopy (POM), X-ray diffraction studies (XRD) and atomic force microscopy (AFM). Remarkably, the position of the acryl group influences the behaviour of the two target molecules in supramolecular assembly, and also in the formation of photoresponsive organic hydrogels or microcrystals.

Multiple Azoarenes Based Systems – Photoswitching, Supramolecular Chemistry and Application Prospects

“…Through a series of theoretical investigations, Guskova and co‐workers revealed various aspects on BTA core‐based tripodal azobenzene derivatives C3‐29 [114] . Our group has also computationally investigated on various tripodal systems using DFT and TD‐DFT methods [90,91,115] …”

“…On the other hand, both of them form excellent self‐assembly (columnar rectangular in C3‐30 , and lamellar in C3‐31 ), albeit inhibiting the photoswitching effects (Figure 22). [115] Haino and coworkers reported azobenzene incorporated C 3 ‐symmetric photoresponsive organogels C3‐28 a – c , and C3‐33 a , b [113,118] . Two component gel has been prepared by mixing a photochromic tripodal molecule C3‐33 a and bispyridines derivatives [118a] …”

“…[114] Our group has also computationally investigated on various tripodal systems using DFT and TD-DFT methods. [90,91,115] The C 3 -symmetric tripodal systems containing multi photochromic units proved as promising scaffolds for gelation properties and exhibiting light-induced sol-gel phase transitions. In this regard, Huang and co-workers have developed a novel photo-responsive organogel C3-32 showing gelation behaviour in various organic solvents and upon irradiation with UV light it displayed reversible sol-gel phase transition.…”

Structure–property relationship in functionalized azobenzene photoswitches and their supramolecular behavior

“…[7][8][9] However, choosing supramolecular synthons, particularly the functional groups and appended units to be functionalized in azobenzenes is crucial. 10,11 The growth of light-controlled supramolecular applications necessitates improving reversible photoswitching in the assembled state and enabling tuneability to the cis-stability of azobenzenes. 10 Considering the increasing demands, functionalized azobenzenes rendering supramolecular prospects have been the subject of several studies in recent times.…”

Azobenzene Based Photo-Responsive Hydrogel: Synthesis, Self-Assembly, and Antimicrobial Activity

“…Photosensitive hydrogels hold tremendous promise for stem cell reprogramming, as they can control precise spatiotemporal over a wide range of parameters. At the same time, their attractive ability to be non-invasive has also attracted the interest of a large number of scientists [ 15 , 16 , 17 ]. The temperature-responsive and shear-thinning properties can be used as injectable hydrogels to encapsulate macromolecular, small-molecular, or cellular cargos in vivo.…”