Photochromic behaviour of Berry Red studied in solution and polymer films

Favaro, Giovanna; Ortica, F.; Romani, A.; Smimmo, Paola

doi:10.1016/j.jphotochem.2007.07.029

Cited by 17 publications

(17 citation statements)

References 16 publications

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“…[9][10][11] Herein, the photochromism is associated to a phase transition, which leads to temperature-dependent photochromism.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

“…[9] The photochromism behavior of chromenes in organic solutions has later been extended to the solid state, [10] polymeric matrices, [11] and also supramolecular systems in which chromenes were used as molecular components of the system. [12] Although the cis/trans photoisomerization of chalcones has been extensively studied in the flavylium networks, the photoactive ring-closure/-opening reaction between B and ortho-quinone allides is more difficult to access due to the transient existence of the hemiketal.…”

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confidence: 99%

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Phase‐Dependent Photochromism of a Lactone‐Stabilized Chromene from a Flavylium Reaction Network

Leydet

Gavara

Cunha‐Silva

et al. 2011

Chemistry A European J

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New trans-2-hydroxychalcones bearing a carboxylate group at position 2' (Ct(-)) were synthesized (compounds 2 and 3). These compounds lead to a network of chemical reactions depending on pH value, light, and solvent. In water, when the pH value is lowered, the ionized trans-chalcone is protonated and the flavylium cation AH(+) is formed at very acidic pH values through hemiketal B and cis-chalcone Cc, with global acidity constants of pK'(a) ≤ -1 and ≈ 0.1, respectively, for 2 and 3. The electron-acceptor character of the carboxylic substituent not only increases the observed acidity of the flavylium cation, but also decreases the rate of the ring-opening/-closing from a subsecond timescale to hours relative to model compound 1 (without carboxylate). The photochemistry of the network was studied in detail by means of continuous irradiation, monitored by UV/Vis absorption and (1)H and (13)C NMR spectroscopic analysis. Although compound 3 is only slightly photoactive, compound 2 (Ct(-)) reacts in aqueous solutions (λ(irr) = 313 nm) to form B(-) and Cc(-), with a global quantum yield of 0.15, and fully reverts back to Ct(-) with a rate constant of k = 6.7×10(-5) s(-1) . The flavylium cation is no longer formed in methanol, and irradiation of Ct(-) leads to the formation of B(-) and the new lactone-trapped chromene species La. The formation of La takes place through a sequence of three photochemical steps: photoisomerization of Ct(-), photo-ring-closing reaction of Cc(-), and photolactonization of B(-). Only the cis/trans isomerization and ring-closing reactions are thermally reversible on a timescale of seconds and hours, respectively. A photochromic system was achieved in rigid matrices of methanol (at 77 K) and 1-dodecanol (5 °C) by irradiating lactone La to give a red ortho-quinone allide through a photo-ring-opening reaction; the color disappears with a rate constant of k = 1.25×10(-2) s(-1) in 1-dodecanol at 5 °C.

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“…[9][10][11] Herein, the photochromism is associated to a phase transition, which leads to temperature-dependent photochromism.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

mentioning

confidence: 99%

Phase‐Dependent Photochromism of a Lactone‐Stabilized Chromene from a Flavylium Reaction Network

Leydet

Gavara

Cunha‐Silva

et al. 2011

Chemistry A European J

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“…can be easily correlated to the dye chemical structure, the solvent polarity and viscosity, allowing for straightforward and often predictable fine tuning of the optical properties. [14][15][16] Unfortunately, this does not apply to solid solutions, i.e. photochromic polymeric films, which are far more relevant for practical applications.…”

Section: Introductionmentioning

confidence: 99%

Highly transparent photochromic films with a tunable and fast solution-like response

2020

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“…The observed rate constant approaches that reported for some of the commercially relevant photochromic compounds used in polymeric films. 71,72 The MON-ormosil composite thin film was found to be stable toward several photochromic coloration and decoloration cycles, validating the photostability and hence robustness of the material to fatigue. In addition, no leaching of the MONs or the constituent linker was observed when the MON-ormosil composite film was immersed in ethanol for several hours, whereas the ormosil doped with DP linker exhibited gradual leaching of the latter, as monitored by UV-vis absorption spectroscopy of the ethanolic solution (Supplemental Information).…”

Section: Entrapment Of 2d Mons In An Ormosil Matrix and Development Of Photochromic Filmsmentioning

confidence: 70%

Photochromic 2D Metal-Organic Framework Nanosheets (MONs): Design, Synthesis, and Functional MON-Ormosil Composite

Mukhopadhyay

Maka

Savitha

et al. 2018

Chem

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Exfoliation of layered porous metal-organic frameworks (MOFs) in a top-down fashion constitutes a successful approach to 2D metal-organic nanosheets (MONs), the analogs of graphene. The planned synthesis of layered MOFs is a challenging crystal-engineering exercise. Development of photochromic MONs that respond to light is a much bigger challenge; indeed, photochromic MONs are heretofore unknown. Here, we demonstrate engineering of layered MOFs and access to photochromic MONs. The strategy entails the use of programmed photochromic organic linkers characterized by a bulged core and metal-mediated self-assembly that occurs only in two dimensions, leading to layered MOFs. MONs exfoliated from such MOFs exhibit brilliant photochromism perceptible to the naked eye. We show that the MONs can be entrapped in an ormosil matrix for the development of polymer composites that display uncomplicated thermal bleaching kinetics. Thus, immobilization of photochromic 2D MONs containing void spaces in a polymer matrix for ophthalmic lens and other applications is compellingly demonstrated.

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Photochromic behaviour of Berry Red studied in solution and polymer films

Cited by 17 publications

References 16 publications

Phase‐Dependent Photochromism of a Lactone‐Stabilized Chromene from a Flavylium Reaction Network

Phase‐Dependent Photochromism of a Lactone‐Stabilized Chromene from a Flavylium Reaction Network

Highly transparent photochromic films with a tunable and fast solution-like response

Photochromic 2D Metal-Organic Framework Nanosheets (MONs): Design, Synthesis, and Functional MON-Ormosil Composite

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