On the acid catalysed isomerisation of some substituted spirobenzopyrans

Roxburgh, Craig J.

doi:10.1016/0143-7208(94)00059-b

Cited by 41 publications

(32 citation statements)

References 8 publications

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“…27 This effect in the contemporary indolinobenzospiropyrans was noted much later (1995) both by Roxburgh and Sammes. 86 The intermediate species observed by 1 H NMR spectroscopy was assigned as either the protonated or non-protonated short-lived cisoid-species. At the same time, Zhou and co-workers assigned an intermediate observed upon protonation of 6 0 ,8 0 -dinitrospiropyran to a protonated form with a broken C spiro -O bond that had not yet achieved planarisation (''species X'').…”

Section: Acidochromism and Ph-gated Z/e-isomerization Of Spiropyransmentioning

confidence: 99%

The evolution of spiropyran: fundamentals and progress of an extraordinarily versatile photochrome

2019

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Section: Acidochromism and Ph-gated Z/e-isomerization Of Spiropyransmentioning

confidence: 99%

The evolution of spiropyran: fundamentals and progress of an extraordinarily versatile photochrome

2019

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“…The interconversion between spiropyran and merocyanine entails chemical and physical variations such as color, dipole moment and optical configuration. If a spiropyran is dispersed or covalently bound to a polymer it can provide this with several properties such as photochromism, thermochromism (Guglielmetti, 2003), acidochromism (Roxburgh & Sammes, 1995) and electrochromism (Monk, Mortimer, & Rosseinsky, 2007). The covalent binding of spiropyrans into polymeric matrices can significantly reduce their photodegradation that is an important limitation to practical application.…”

Section: Introductionmentioning

confidence: 98%

Synthesis and photochromic response of a new precisely functionalized chitosan with “clicked” spiropyran

Bertoldo

Nazzi

Zampano

et al. 2011

Carbohydrate Polymers

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“…[1] Over the last decades, investigation on photochromic materials has develop into powerful areas of research because of their latent applications in information storage, smart windows, optical lenses, optical switches, logic gates, and fluorescence modulators. [2,3] There are many research groups worldwide having particular interest in the design, synthesis, and photophysical studies of different photochromic families. [4][5][6][7][8][9][10] So far, a variety of photochromic materials, such as spirobenzopyrans, [11] chromenes, [12] diarylethenes, [13] and dihydroindolizine and tetrahydroindolizine, [14][15][16][17][18][19][20][21][22] have been developed to meet the requirements of optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Photochromism of dihydroindolizines Part XIX. Efficient one-pot solid-state synthesis, kinetic, and computational studies based on dihydroindolizine photochromes

Ahmed

Guesmi

Asghar

et al. 2016

J. Phys. Org. Chem.

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For the first time, one‐pot solid‐state synthesis of 12 photochromic materials based on photochromic dihydroindolizine system substituted in both fluorene part (region A) and the heterocyclic part (region C) has been established. This method has immense advantages, which are short‐time reaction, high‐yield and low‐yield by‐products, and easily purification and separation processes. In addition, this method will help in getting over the tremendously purification and low‐yield problems faced since the worth‐finding of this family of photochromic materials. The absorption maxima (λmax) and the half‐lives (t1/2) of the colored betaines were detected in all cases using multichannel UV/Vis spectrophotometric measurements. The rate constants of the thermal back reaction of the betaines were determined at constant temperature by measuring the decrease in the maximum absorption intensity (λmax) with time. The half‐lives (t1/2) and rate constants (k) of betaines under examination were calculated by plotting lnA against time (t). The kinetic measurements could be detected by both spectra scan and time‐dependent decay measurements. Examination of the Arrhenius parameters reveals an underlying compensation between Ea and log A, whereby an increase in Ea is opposed by an increase in log A. The compensation appears in the corresponding Eyring parameters, ΔH≠ and ΔS≠; betaine structural changes that lead to lower, more favorable enthalpies of activation engender opposing entropic changes. At the isokinetic temperature Tiso = β, structural changes do not affect the rate constant of a reaction series because the changes of ΔH≠ are counterbalanced by changes of ΔS≠. The existence of an isokinetic relationship indicates a common structure of the transition state of all thermal back reaction of betaine under investigation. The computational results suggest that the decoloration reaction is a two‐step mechanism. The first step corresponds to the transoid–cisoid isomerization with an activation barrier of 10.3 kJ mol−1, and the second step is the ring closure from the cisoid intermediate with a barrier 71.3 kJ mol−1, which represent the rate determining step for thermal decoloration. The photochemical ring opening of DHIs to betaines is a disrotatory 1,5‐electrocyclic reaction, whereas the thermal ring‐closing occurs in the conrotatory mode. Copyright © 2016 John Wiley & Sons, Ltd.

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On the acid catalysed isomerisation of some substituted spirobenzopyrans

Cited by 41 publications

References 8 publications

The evolution of spiropyran: fundamentals and progress of an extraordinarily versatile photochrome

The evolution of spiropyran: fundamentals and progress of an extraordinarily versatile photochrome

Synthesis and photochromic response of a new precisely functionalized chitosan with “clicked” spiropyran

Photochromism of dihydroindolizines Part XIX. Efficient one-pot solid-state synthesis, kinetic, and computational studies based on dihydroindolizine photochromes

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