1,2-Diarylbenzene as fast T-type photochromic switch

Kitagawa, Daichi; Nakahama, Tatsumoto; Nakai, Yutaka; Kobatake, Seiya

doi:10.1039/c8tc05357j

Cited by 52 publications

(67 citation statements)

References 36 publications

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“…This may indicate that the ring-closed species, being relatively insusceptible to oxidation by the presence of the C11 and C13 methyl groups, undergoes a fast thermal cycloreversion that precludes its spectroscopic detection. 53 We will return to this issue in section 2.2 .…”

Section: Resultsmentioning

confidence: 99%

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Photoinduced Changes in Aromaticity Facilitate Electrocyclization of Dithienylbenzene Switches

et al. 2020

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The concepts of excited-state aromaticity and antiaromaticity have in recent years with increasing frequency been invoked to rationalize the photochemistry of cyclic conjugated organic compounds, with the long-term goal of using these concepts to improve the reactivities of such compounds toward different photochemical transformations. In this regard, it is of particular interest to assess how the presence of a benzene motif affects photochemical reactivity, as benzene is well-known to completely change its aromatic character in its lowest excited states. Here, we investigate how a benzene motif influences the photoinduced electrocyclization of dithienylethenes, a major class of molecular switches. Specifically, we report on the synthesis of a dithienylbenzene switch where the typical nonaromatic, ethene-like motif bridging the two thienyl units is replaced by a benzene motif, and show that this compound undergoes electrocyclization upon irradiation with UV-light. Furthermore, through a detailed quantum chemical analysis, we demonstrate that the electrocyclization is driven jointly and synergistically by the loss of aromaticity in this motif from the formation of a reactive, antiaromatic excited state during the initial photoexcitation, and by the subsequent relief of this antiaromaticity as the reaction progresses from the Franck–Condon region. Overall, we conclude that photoinduced changes in aromaticity facilitate the electrocyclization of dithienylbenzene switches.

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Section: Resultsmentioning

confidence: 99%

“…Interestingly, this indicates that the absence noted in section 2.1 of a change in the experimental absorption spectrum of Me 4 -1a upon irradiation with UV-light, is not related to the influence of the C11 and C13 methyls on the cycloreversion, but rather to their ability to prevent oxidation of the ring-closed species. 53 …”

Section: Resultsmentioning

confidence: 99%

Photoinduced Changes in Aromaticity Facilitate Electrocyclization of Dithienylbenzene Switches

et al. 2020

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“…[24][25][26][27] Very recently, we have succeeded in developing a T-type photochromic compound, 1,2diarylbenzene (DAB) by only introducing a tetrafluorobenzene ring to the ethene bridge of a representative DAE, 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene (Scheme 1). 28 DAB (1a) undergoes photocyclization upon irradiation with ultraviolet (UV) light and fast thermal cycloreversion with a t1/2 of 130 ms at 298 K. However, 1a has several limitations in practical applications such as photochromic ophthalmic lenses. Specifically, 1a has almost no absorption in the UV-A region (315-400 nm), and the absorbance at visible region of the closed-ring isomer 1b upon irradiation with UV (313 nm) light is very small because of the extremely rapid thermal cycloreversion.…”

Section: Introductionmentioning

confidence: 99%

Tuning of Optical Properties and Thermal Cycloreversion Reactivity of Photochromic Diarylbenzene by Introducing Electron-Donating Substituents

2019

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Thermally reversible photochromic compounds having excellent physicochemical properties can be exploited for many practical applications, such as ophthalmic lenses, real-time holography, and super-resolution microscopy. In this study, we have designed and synthesized novel 1,2diarylbenzene derivatives bearing various electron-donating substituents at p-position of the 2 phenyl ring to tune the optical and thermal properties for the practical applications. Introduction of the electron-donating groups resulted in the red-shift of the absorption spectra, increase in the absorption coefficients of the open-ring isomers, and deceleration of the thermal cycloreversion of the closed-ring isomers. Theoretical analysis based on Hammett's substituent constant and density functional theory revealed that the rate of thermal cycloreversion became lower in proportion to the electron-donating ability of the substituent. The novel 1,2-diarylbenzene derivatives synthesized here could undergo photocyclization upon irradiation with UV-A light and fast thermal cycloreversion with a half-life of a few hundred milliseconds to seconds.

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“…The obtained activation energies (74 kJ.mol -1 for BTP1 c and 67 kJ.mol -1 for 1Y c ) are clearly lower than those observed for P-type classical DTEs (based on the perfluorocyclopentene core) that show typical values as large as 140 kJ.mol -1 [2,26,43]. They are nevertheless comparable to other fast bleaching systems like dithienyl thiazole derivatives [44] (80 to 90 kJ.mol -1 ), phenanthrene-based compounds [45] (50-60 kJ.mol -1 ) as well as perfluorobenzene-based compounds [29] (66 kJ.mol -1 ) and clearly reveal that the origin of this fast bleaching is the low stability of the closed form that correlates with low activation energies for the cycloreversion reaction. This is further confirmed by theoretical investigations (see below).…”

Section: Study Of Photochromism By 1 H Nmr Spectroscopy At Variable Tmentioning

confidence: 70%

“…Typically, DAE with phenanthrene bridges [27][28] show low photoconversions and fast thermal bleaching of their closed isomer due to the loss of aromaticity upon photocyclisation. For example, a central fluorinated benzene ring can provide fast T-type photochromic DAE with a half-life of 130 ms at room temperature [29]. Recently, Diederich et al demonstrated that DAE with a central pyrazine bridge like 2,3-bis(2,5-dimethylthiophen-3-yl)pyrazine are also T-photochromes with a thermal half-life of ca.…”

Section: Introductionmentioning

confidence: 99%

Coordination-enhanced photochromism in dysprosium dinuclear complexes with photomodulated single-molecule magnet behavior

Norel¹,

Bernot²,

Gendron³

et al. 2020

Chem.Sq.

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We report the synthesis of a pyrazine-based bis-tridentate diarylethene (DAE) ligand and the corresponding dinuclear yttrium and dysprosium complexes that all show T-type photochromism. Large changes in the photochromic behaviour are induced by metal coordination, including a tuning of the bleaching rate by several orders of magnitude, characterized through VT-NMR and supported by theoretical calculations. The dysprosium dinuclear complex shows a single-molecule magnet (SMM) behaviour, under an external applied magnetic field, significantly modulated upon photoisomerization. This feature is further analyzed through ab initio calculations.

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1,2-Diarylbenzene as fast T-type photochromic switch

Abstract: A novel fast T-type photochromic molecular system, 1,2-diarylbenzene, was successfully developed.

Cited by 52 publications

References 36 publications

Photoinduced Changes in Aromaticity Facilitate Electrocyclization of Dithienylbenzene Switches

Photoinduced Changes in Aromaticity Facilitate Electrocyclization of Dithienylbenzene Switches

Tuning of Optical Properties and Thermal Cycloreversion Reactivity of Photochromic Diarylbenzene by Introducing Electron-Donating Substituents

Coordination-enhanced photochromism in dysprosium dinuclear complexes with photomodulated single-molecule magnet behavior

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