Photoswitchable Turn-on Mode Fluorescent Diarylethenes: Strategies for Controlling the Switching Response

Abstract

University. He has been conducting research on molecular photoswitches for the last 40 years. In the middle of the 1980s he discovered thermally irreversible and fatigue resistant photochromic diarylethenes. His current interests focus on the development of light-driven molecular-crystal actuators and turn-on mode fluorescent diarylethenes for super-resolution fluorescence microscopies. Masakazu Morimoto AbstractA new type of photoswitchable fluorescent diarylethenes, which have no fluorophore unit but emit strong fluorescence (¯f ³ 0.9) in the closed-ring isomers, has been developed. They are sulfone derivatives of 1,2-bis(2-alkyl-4-methyl-5-phenyl-3-thienyl)perfluorocyclopentenes and 1,2-bis(2-alkyl-1-benzothiophen-3-yl)perfluorocyclopentenes. By chemical modifications of the structures their switching response was tuned to meet the requirements for super-resolution fluorescence microscopies. The water-soluble derivatives have been successfully applied to acquire super-resolution bioimages using a single-wavelength visible beam.Fluorescence is the most convenient tool to detect small amounts of molecules.1 Even single molecules can be detected using fluorescence owing to remarkable progress of optical detection techniques. 24 Various types of highly fluorescent chromophores have been synthesized and widely applied in materials and life sciences, such as microanalysis and bioimaging.59 Their application is expected to be further extended when an additional switching property is provided to the chromophores. 10 The changes in fluorescence spectra and/or intensity by external stimuli, such as chemicals, electrons (or holes) or photons, are ingeniously adopted for analysis and imaging. When the fluorescence is photoactivated or switched on and off upon photoirradiation, the fluorescence modulation offers the opportunities to monitor diffusion processes in real time, 1113 store optical information in memory media, 1420 and increase the resolution in imaging. 10,2023 There are two types of fluorescence switching molecules, photoactivatable and photoswitchable ones. The photoactivatable molecules irreversibly switch from non-fluorescent to fluorescent states, while photoswitchable ones undergo reversible switching between fluorescent and non-fluorescent states. The reversibly photoswitchable molecules can be designed and constructed by integrating both photochromic and fluorescent chromophores in a molecule. 1420 Based on this strategy

Photochromic fluorophores at the molecular and nanoparticle levels: fundamentals and applications of diarylethenes

“…In the present review, such conventional "turn-off" mode fluorescent DAEs are excluded because a great number of such derivatives have been synthesized so far, and the corresponding results have already been summarized in previous excellent reports 10,15 . On the other hand, turn-on mode fluorescent DAEs, which are initially nonfluorescent and are activated to a fluorescent state upon photoisomerization reactions, have recently been developed [18][19][20][21][22][23][24][25][26][27][28] . Such turn-on mode fluorescent DAEs are suitable for bioimaging applications, including superresolution microscopies.…”

“…Furthermore, 6b exhibits excellent fatigue resistance under irradiation with visible (>440 nm) in 1,4-dioxane, which is superior to that of Rhodamine 101 in ethanol. Further investigations regarding the effect of aryl substituents at the 6-and 6′-positions and alkyl substituents at the 2-and 2′-positions on the photoswitching performance and oxidized terarylene derivatives have been carried out [23][24][25][26][27][28] .…”

“…The detailed explanation of this point was well described in refs. 24,25 . Several researchers tried to develop fluorescent DAEs and demonstrate superresolution fluorescence imaging by using such derivatives.…”

1,2‐Disubstituted 3,3,4,4,5,5‐Hexafluorocyclopentenes as Bent Light‐Emitting π‐Conjugated Luminophores

“…Recently, organic molecules containing hexafluorocyclopentene cores have drawn considerable interest for application to the field of organic materials In 2000, Irie et al first developed photochromic compounds containing the hexafluorocyclopentene scaffold A , which are applicable to optoelectronic devices (Figure ). Further exploration of novel hexafluorocyclopentene‐based organic materials successfully led to the development of photoresponsive actuators ( B ), turn‐on‐type fluorescence switching materials ( C ), solid‐state luminophores ( D ), n‐type semiconducting materials ( E ), and organic oxidants ( F ) (Figure ) …”

Turn‐On Fluorescent Photochromic Disulfonylarylthiophenes: Effect of Sulfone Groups on Fluorescence and Conversion

“…Previously, we reported a new type of turn-on mode fluorescent photochromic molecules based on the diarylethene skeleton, which are sulfone derivatives of 1,2-bis(benzothiophenyl)ethenes. [4][5][6]18,19 Diarylethene 1 is a photochromic material that can be readily produced through the Suzuki reaction using dibromothiophene as a starting material. Since then, various types of fluorescent diarylethenes with disulfonylbenzothiophene groups have been published (Scheme 1).…”