Unprecedented dual aggregation‐induced emission (AIE) behavior based on a steric‐hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π–π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off‐to‐on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off‐to‐on fluorescent photoswitch is successfully established in super resolution imaging.
An unprecedented light-driven chiral switching supramolecular system exhibits reversible and enantiospecific transformation along with a unique concerted photoconversion process. It is guidable for the development of light-driven supramolecular architectures, especially for stimuli-responsive chiral functional materials.
The fast light-responsive dithienylethenes
(DTEs) are one of the
most attractive photochromic families because of their excellent thermal
irreversibility and fatigue resistance. However, the all-visible-light-activated
DTE system still remains challenging because most of them require
the harmful high-energy ultraviolet light to trigger their photocyclization
reaction. Here, we have for the first time borrowed a specific intramolecular
proton transfer (IPT) process and rationally designed a series of
all-visible-light-driven DTEs. Incorporating the IPT-functional group
to DTE unit gives rise to an extra absorption band with a distinct
red shift, which enables the photocyclization of DTEs under stimuli
of visible light at 450 nm, as well as ensuring the desirable photoswitching
efficiency. The isomerization from OH form to NH form induced by IPT
can decrease the energy gap for excitation and photocyclization, thereby
affording the all-visible-light-triggered photochromic performance,
which can not only work well in a polar solvent system but also show
its effectiveness in polymeric gel systems. In this regard, we can
provide a general and reliable platform to construct all-visible-light-driven
DTEs with excellent reversible photoswitching and broad applicability,
especially with avoiding the use of harmful ultraviolet light to induce
their photocyclization.
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