All‐Visible‐Light Triggered Photoswitch of Dithienylethene Derivatives with Molecular Conformation Changes Excess 5 Å

Abstract

Developing new all‐visible‐light driven fluorescent molecular switches has attracted much interests due to their important application prospects in materials science and life science. Herein, three novel all‐visible‐light triggered fluorescent molecular photoswitches (2P3, 4F, and 4Cl) are designed and prepared, which are realized by prolonging π‐conjugation length with aggregated‐induced emission units. These photoswitches show reversible photochromic and fluorescent switching in dilute solutions and films under 420 nm and 560 nm irradiations. Meanwhile, upon alternating irradiations with 450 nm/560 nm light, effective photochromic and fluorescent switching in powder states are also achieved. More interestingly, two distinct conformations with different photochromic abilities can be altered by solvents polarity. The size difference of the two conformations is over 5 Å in the vertical direction which is one of the largest changes among photochromic molecules based on dithienylethene. The accompanying conformational changes are analysed to understand the relationship between solvent characteristics and crystal structure, as well as the intermolecular interaction in solid state for all‐visible‐light triggered photoswitching molecules.

Recent advances in small-molecule fluorescent photoswitches with photochromism in diverse states

“…In addition, it was found that the compounds connected with tetraphenylethene and BTE showed brighter emission than those with triphenylethene and BTE in the solid state. In addition, Luo et al 136 synthesized three fluorescent molecular optical switches with similar structures by extending the π conjugate length of the aggregation-induced emission units. These optical switches showed two different conformations in different polar solvents, resulting in different photochromic behaviours, which are used for visible-light manipulated data storage and anti-counterfeiting.…”

Towards Optical Information Recording: A Robust Visible‐Light‐Driven Molecular Photoswitch with the Ring‐Closure Reaction Yield Exceeding 96.3 %

“…In essence, a highly efficient visible light system usually rely on constructing a conjugated molecule system no matter it is triplet energy transfer, intramolecular proton transfer, or nonlinear optics. In comparison, the simpler and more direct approach to visible light responsibility is to extend the π‐conjugation length of the molecule to shift the absorption wavelength into the visible light region [9d,18] . However, this approach frequently doesn't work, as an conjugation‐extended diarylethene system commonly results in reduce of the photochromic efficiency and even the photoswitching capacity [19] .…”

Customizable High-Contrast Optical Responses: Dual Photosensitive Colors for Smart Textiles

“…14 Reported instances of organic photochromic materials showcase a myriad of color change mechanisms, such as intermolecular electron transfer, 15 constitutional transformations, 16 and conformational changes. 17 Despite the significant progress made so far in this field, the development of multifunctional photochromic dyes with high contrast, reversibility, and scalability, which are fundamental features for smart textile applications, remains a challenge.…”

“…Notably, organic photochromic colorants are especially suited for textile applications, primarily owing to their diverse color range, cost-effectiveness, and versatility in terms of structure and properties . Reported instances of organic photochromic materials showcase a myriad of color change mechanisms, such as intermolecular electron transfer, constitutional transformations, and conformational changes . Despite the significant progress made so far in this field, the development of multifunctional photochromic dyes with high contrast, reversibility, and scalability, which are fundamental features for smart textile applications, remains a challenge.…”