Fluorescent Azobenzene-Containing Compounds: From Structure to Mechanism

Abstract

The reversible photoisomerization of azobenzenes has been extensively studied to construct systems with optical responsiveness; however, this process limits the luminescence of these compounds. Recently, there have been many efforts to design and synthesize fluorescent azobenzene compounds, such as inhibition of electron transfer, inducing aggregation, and metal-enhancement, which make the materials ideal for application in fluorescence probes, light-emitting devices, molecular detection, etc. Herein, we review the recently reported progress in the development of various fluorescent azobenzenes and summarize the possible mechanism of their fluorescence emission. The potential applications of these materials are also discussed. Finally, in order to guide research in this field, the existing problems and future development prospects are discussed.

Multi‐Stimuli Responsive Thiazolothiazole Viologen‐Containing Poly(2‐Isopropyl‐2‐Oxazoline) and Its Multi‐Modal Thermochromism, Photochromism, Electrochromism, and Solvatofluorochromism Applications

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signals with regenerated and reusable characters have received a great deal of attention recently for their numerous applications in high-tech fields such as sensors, [1] smart windows, [2,3] displays, [4] rewritable copy papers, [5] secret writings, [6] anti-counterfeiting, etc. [7][8][9][10] Among multistimuli responsive materials, crystalline chromic compounds such as spiropyran, [11] azobenzene, [12] diarylethenes, [13] spirooxazine, [14] and viologen, [14] with reversible hue shifts have received a significant lot of interest. They have extremely adaptable and configurable geometric structures, have convenient and efficient chromic functionality, and are readable corresponding singles with regenerated and reused characters in response to external stimuli.

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Blue-red emitting materials based on a pyrido[2,3-b]pyrazine backbone: design and tuning of the photophysical, aggregation-induced emission, electrochemical and theoretical properties

“…15 Moreover, molecule 6 shows faint emission in THF, CHL and quenched emission in rest other solvents, which could be due to cis – trans photoisomerization of azobenzene chromophores. 17 …”

“…In the case of dye 6 nonemissive nature at the aggregate state and AIE inactivity could be due to the inability of the molecule to restrain photoisomerization of the azo (–N N–) core at the aggregate state. 17,26 While AIE inactivity in molecules 8 and 9 could be justified by the covalent locking of donor phenyl ring by oxygen and sulphur, respectively. Here, the RIR process does not work in the aggregate state as its donor phenyl ring rotations are already locked by the “O/S” bridges, and hence its emission at high f w is not enhanced and AIE inactivity for these dyes are observed.…”

A review on photochemical sensors for lithium ion detection: relationship between the structure and performance

“…33,34 Detection with the naked eye, short analysis time, low detection cost (cheapness), simplicity of the system, selectivity, reversibility, and no need for complex tools are the advantages of these sensors. 35 The structure and isomerization of the most important and widely used photochromic compounds such as spiropyran, spirooxazine, 36 azobenzene 37 and diarylethene 38 are shown in Fig. 1, which can be used in the design of optical detectors.…”