Photochromic reaction in 3<i>H</i>-naphthopyrans studied by vibrational spectroscopy and quantum chemical calculations

Brazevic, Sabina; Niziński, Stanisław; Szabla, Rafał; Rode, Michał F.; Burdziński, Gotard

doi:10.1039/c9cp01451a

Cited by 17 publications

(77 citation statements)

References 47 publications

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“…Photoexcitation of CF leads to the ring‐opening reaction with a quantum yield of 0.75 . The early stages of the photoreaction have been studied for CF by Herzog et al .…”

Section: Resultsmentioning

confidence: 99%

“…Figure A shows our picosecond mid‐IR data recorded with 0.3 ps temporal resolution for CF in acetonitrile‐d 3 . Selection of 365 nm as the excitation wavelength causes selective excitation of the S 1 (π,π*) state . A distinctive initial absorption band shows a product peak at about 1625 cm −1 , it undergoes a frequency up‐shift to 1638 cm −1 and band narrowing due to vibrational cooling.…”

Section: Resultsmentioning

confidence: 99%

“…The TC formation and its decay in room‐temperature conditions can be traced by UV‐vis and mid‐IR transient absorption . The TC → TT photoisomerization has been recently observed by FT‐IR and UV‐vis upon continuous UV LED irradiation . Contribution of the TC → TT photoisomerization, which is typically unwanted in applications, can be hypothetically reduced under presence of highly efficient competing channels in deactivation of TC in the singlet excited state.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast Dynamics of the Transoid‐cis Isomer Formed in Photochromic Reaction from 3H‐Naphthopyran

et al. 2020

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Recent efforts in designing new 3H‐naphthopyran derivatives have been focused on efficient coloration process with a short fading time of the colored transoid‐cis TC isomer. It is desirable to avoid photoisomerization of TC leading to transoid‐trans TT isomers in the photoreaction. Long lifetime of TT can hamper fast applications such as dynamic holographic materials and molecular actuators, the residual color is one of the serious issues for photochromic lenses. Herein we characterize the photophysical and photochemical channels of TC excited state deactivation competing with the unwanted TC→TT isomerization process. Transient absorption spectroscopy reveals a very short lifetime of the singlet excited TC (≈0.8 ps) and its deactivation channels as S1→S0 internal conversion (major), intersystem crossing S1→T1, pyran ring formation, photoenolization and TC→TT isomerization. Computations support the S1→S0 and T1→S0 channels as responsible for photostabilization of the TC form.

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“…Photoexcitation of CF leads to the ring‐opening reaction with a quantum yield of 0.75 . The early stages of the photoreaction have been studied for CF by Herzog et al .…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrafast Dynamics of the Transoid‐cis Isomer Formed in Photochromic Reaction from 3H‐Naphthopyran

et al. 2020

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“…Even though, in both forms the strongest S 0 →S 2 transition is slightly red shifted for TC relative to its position for TT ( Figure 1 b). The methoxy group substitution does not change much the chromene’s ground-state energy landscape (calculated at the MP2/cc-pVDZ theory level) leaving the S 0 -state energy barriers almost unchanged [ 28 ]. Thus, similarly as in the H counterpart, TC-OCH 3 and TT-OCH 3 forms do not differ much energetically.…”

Section: Resultsmentioning

confidence: 99%

“…The discrepancy can be explained by a small contribution of the single-photon reaction, additionally to the main consecutive two-photon absorption reaction path. We performed numerical simulations (see SI for details) for CF-H in cyclohexane using photophysical properties determined recently [ 28 ] that quantify for the first time the yields of both processes. A quantum yield of 0.003 for the single-photon channel explains the experimental data ( Figure 2 b, the slope of 1.5).…”

Section: Resultsmentioning

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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Photochromic Naphthopyran Dyes Incorporating a Benzene, Thiophene, or Furan Spacer: Effect on Photochromic, Optoelectronic, and Photovoltaic Properties in Dye‐Sensitized Solar Cells

et al. 2021

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We recently demonstrated that diaryl-naphthopyran photochromic dyes are efficient for sensitization of TiO2 mesoporous electrodes, thus allowing the fabrication of photo-chromovoltaic cells that can self-adapt their absorption of light and their generation of electricity with the light intensity. Herein we report the synthesis, the characterisation of two novel photochromic dyes based on diaryl-naphthopyran core i.e NPI-ThPh and NPI-FuPh for use in Dye Sensitized Solar Cells (DSSCs). Compared to our reference dye NPI, the molecules only vary by the nature of the spacer, a thiophene or a furan, connecting the photochromic unit and the phenyl-cyano-acrylic acid moiety used as the anchoring function. We found that swapping a phenyl for a thiophene or a furan leads to an improvement of the absorption properties of the molecules both in solution and after grafting on TiO2 electrodes, however their photochromic process becomes not fully reversible. Despite better absorption in the visible range, the new dyes show poorer photochromic and photovoltaic properties in devices compared to NPI.Thanks to UV-Vis spectroscopy, DFT calculation, electrical characterization of the cells, and impedance spectroscopy, we unravel the factors limiting their performances. Our study Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff))The data that support the findings of this study are available from the corresponding author upon reasonable request and in the supporting information. References

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Photochromic reaction in 3H-naphthopyrans studied by vibrational spectroscopy and quantum chemical calculations

Abstract: Time resolved mid-IR spectroscopy facilitates selective detection of transoid-cis and transoid-trans species.

Cited by 17 publications

References 47 publications

Ultrafast Dynamics of the Transoid‐cis Isomer Formed in Photochromic Reaction from 3H‐Naphthopyran

Ultrafast Dynamics of the Transoid‐cis Isomer Formed in Photochromic Reaction from 3H‐Naphthopyran

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

Photochromic Naphthopyran Dyes Incorporating a Benzene, Thiophene, or Furan Spacer: Effect on Photochromic, Optoelectronic, and Photovoltaic Properties in Dye‐Sensitized Solar Cells

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