Efficient coloration and decoloration reactions of fast photochromic 3H–naphthopyrans in PMMA-b-PBA block copolymer

Mutoh, Katsuya; Kobayashi, Yoshihiro; Abe, Jiro

doi:10.1016/j.dyepig.2016.11.004

Cited by 29 publications

(25 citation statements)

References 26 publications

(33 reference statements)

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“…The photoactive fused‐naphthopyrans 4 , 5 were dispersed in Kurarity [Co‐polymer composed of poly(methyl methacrylate) (Tg 100–120 °C) and poly(butyl acrylate) (Tg 40–50 °C )] providing transparent thin films (loading 0.8 %) , , , . The material doped with the fused‐naphthopyran 4 is uncolored in the dark, while with compound 5 the film presented a slight yellowish coloration.…”

Section: Resultsmentioning

confidence: 99%

Joining High Coloration and Fast Color Fading with Photochromic Fused‐Naphthopyrans

Sousa

Coelho

2020

Eur J Org Chem

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An easy synthesis of photochromic naphthopyrans with a lactone ring linking the naphthalene core to the pyran double bond is described. UV irradiation (or exposure to sunlight) of these uncolored compounds provide a single photoisomer with an intense orange coloration that returns completely to the initial uncolored state much faster than common naphthopyrans used in commercial photochromic ophthalmic lenses. A polymeric uncolored material doped with one of these lactone‐fused naphthopyrans develops an intense orange coloration (ΔAbs = 0.73) when exposed to the UV light for 30 s, at room temperature, and returns to the uncolored state in just 1 min. The use of these photochromic compounds allows a faster adaptation of the material's coloration to the surrounding UV‐light intensity, without compromising the color intensity, an important feature to create high performance photochromic ophthalmic lenses.

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Section: Resultsmentioning

confidence: 99%

Joining High Coloration and Fast Color Fading with Photochromic Fused‐Naphthopyrans

Sousa

Coelho

2020

Eur J Org Chem

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“…We prepared a triblock copolymer film (KURARITY LA2330, Kuraray Co., Ltd.) composed of poly (methyl methacrylate) and poly (butyl acrylate) (PBA) doped with equal amounts of 7MR‐Y and 5MR‐B because the superimposed spectra of these two derivatives uniformly cover the whole visible‐light region and their thermal back‐reaction speeds are similar (7MR‐Y: τ 1/2 = 2.3 s and 5MR‐B: τ 1/2 = 1.3 s). The photochromic properties of the film are similar to those in solution because the PBA component has a low glass‐transition temperature, although the conformation changes of photochromic compounds are generally inhibited in rigid polymer matrices . Upon irradiation with light from a solar simulator (350–1100 nm, AM 1.5G), the film clearly changes from colorless to gray ( Figure ).…”

Section: Methodsmentioning

confidence: 94%

On‐Demand Control of the Photochromic Properties of Naphthopyrans

et al. 2018

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minutes/hours to completely return to the CF. The residual color imparted by the TT form and the slow thermal back-reaction of the TC form are considered as problems to be solved. [9][10][11][12][13] The thermal backreaction speed of colored naphthopyrans can be modulated by the introduction of an electron-donating group at the para position of the 3-phenyl ring. [4] However, substitution at the 3-phenyl ring typically causes significant changes in the color of the colored species. Although the speed of the thermal back-reaction can be modulated by exploiting steric effects to destabilize the TC form and the long-lived TT form, the synthetic procedures required to yield the desired products are not simple and moderate control of the thermal backreaction speed for photochromic lenses is difficult to achieve. [14][15][16][17][18][19] In order to design appropriate naphthopyran derivatives showing on-demand photochromic properties, the independent control of the thermal back-reaction speed is an important challenge in the development of advanced photochromic materials. Within this context, we herein present a molecular design strategy that can be used to modulate the thermal fading speed without significant changes to other photochromic properties.In this study, we designed novel naphthopyran derivatives possessing alkylenedioxy moieties as a means to control the thermal fading speed of the TC form and reduce the generation of the long-lived TT form. The reactivity and optical properties of the 1,2-alkylenedioxy benzene significantly depend on the ring-size of the alkylenedioxy moiety owing to changes in electron-donating ability and π-conjugation length upon changing the conformation of the ring. [20][21][22] We introduced alkylenedioxy moieties to the 9-and 10-positions of 3H-naphthopyran (3HNP) and investigated the effects of ring size on the photochromic properties of the resultant molecules. Remarkably, the thermal back-reaction speed of the newly designed naphthopyran derivatives was found to be controllable independently of other photochromic properties, such as the color of the colored species, by changing the alkyl chain length of the alkylenedioxy moiety. In addition, intramolecular hydrogen bonding is very important for modulating the conformation and stability of the structural isomers. [23,24] The undesirable residual color attributable to the formation of the TT form upon cessation of light irradiation is effectively reduced owing to the hydrogen bonding between the oxygen atom at the 10-position and the olefinic proton at the 1-position in the TC form, resulting in fast photoswitchable Photofunctional compounds have emerged as critically important materials for both fundamental studies and industrial applications. Control of the thermal decoloration speed to within several seconds while sustaining satisfactory photochromic colorability is an important challenge for the application of such materials to photochromic lenses and smart windows. Photochromic naphthopyran derivatives are utilized for photoch...

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“…While the TC form relaxes over tens of seconds, the persistence of the long-lived TT form over hours is a limiting factor for classical applications such as photochromic lenses, due to inconvenient slow fading response to UV light switch off. Thus, recent research has been focused on minimization of the TT formation yield in the photoreaction by designing new 3 H -naphthopyran derivatives with appropriate substituents [ 21 , 22 , 26 , 27 ]. Aryl substituents in position 2 of 3 H -naphthopyrans can exert both steric and electrostatic repulsion effects which have been suggested to suppress TT formation [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Control of the Photo-Isomerization Mechanism in 3H-Naphthopyrans to Prevent Formation of Unwanted Long-Lived Photoproducts

Brazevic

Niziński

Śliwa

et al. 2020

IJMS

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In the photochromic reactions of 3H-naphthopyrans, two colored isomers TC (transoid-cis) and TT (transoid-trans) are formed. In terms of optimized photo-switchable materials, synthetic efforts are nowadays evolving toward developing 3H-naphthopyran derivatives that would not be able to photoproduce the long-living transoid-trans, TT, photoproduct. The substitution with a methoxy group at position 10 results in significant reduction of the TT isomer formation yield. The TC photophysics responsible for TT suppression were revealed here using a combination of multi-scale time resolved absorption UV-vis spectroscopy and ab initio calculations. The substitution changes the TC excited-state potential energy landscape, the bicycle-pedal isomerization path is favored over the rotation around a single double bond. The bicycle-pedal path is aborted in halfway to TT formation due to S1→S0 internal conversion populating back the TC species in the ground electronic state. This is validated by a shorter TC S1 state lifetime for methoxy derivative in comparison to that of the parent-unsubstituted compound (0.47 ± 0.05 ps vs. 0.87 ± 0.09 ps) in cyclohexane.

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Efficient coloration and decoloration reactions of fast photochromic 3H–naphthopyrans in PMMA-b-PBA block copolymer

Cited by 29 publications

References 26 publications

Joining High Coloration and Fast Color Fading with Photochromic Fused‐Naphthopyrans

Joining High Coloration and Fast Color Fading with Photochromic Fused‐Naphthopyrans

On‐Demand Control of the Photochromic Properties of Naphthopyrans

Control of the Photo-Isomerization Mechanism in 3H-Naphthopyrans to Prevent Formation of Unwanted Long-Lived Photoproducts

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