Color and constitution. Part <b>8</b>. Some novel dyestuffs containing indoxyl residues

Katritzky, Alan R.; Li, Qiaoling; Fan, Wei‐Qiang

doi:10.1002/jhet.5570250503

Cited by 20 publications

(3 citation statements)

References 15 publications

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“…1 Its synthesis is remarkably easy; a simple one-step condensation reaction between indoxyl acetate and an aldehyde furnishes the chromophore in good yields. 46,47 Despite the long time hemiindigo has been known, the ease of its synthesis, and earlier studies of spectral properties, its photoreactions have only much later been scrutinized. These studies showed a rather complex photochemistry with [2 + 2]cycloadditions 48,49 or triplet generation 49 as possible reaction pathways in the excited state.…”

Section: Applicationsmentioning

confidence: 99%

Indigoid Photoswitches: Visible Light Responsive Molecular Tools

2018

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Indigoid photoswitches comprise a class of chromophores that are derived from the parent and well-known indigo dye. Different from most photoswitches their core structures absorb in the visible region of the spectrum in both isomeric states even without substitutions, which makes them especially interesting for applications not tolerant of high-energy UV light. Also different from most current photoswitching systems, they provide highly rigid structures that undergo large yet precisely controllable geometry changes upon photoisomerization. The favorable combination of pronounced photochromism, fast and efficient photoreactions, and high thermal bistability have led to a strongly increased interest in indigoid photoswitches over the last years. As a result, intriguing applications of these chromophores as reversible triggering units in supramolecular and biological chemistry, the field of molecular machines, or smart molecules have been put forward. In this Account current developments in the synthesis, mechanistic understanding of light responsiveness, advantageous properties as phototools, and new applications of indigoid photoswitches are summarized with the focus on hemithioindigo, hemiindigo, and indigo as key examples. Many methods for the synthesis of hemithioindigos are known, but derivatives with a fourth substituent at the double bond could not easily be prepared because of the resulting increased steric hindrance in the products. Recent efforts in our laboratory have provided two different methods to prepare these highly promising photoswitches in very efficient ways. One method is especially designed for the introduction of sterically hindered ketones while the second one allows rapid structural diversification in only three high-yielding synthetic steps. Given the lesser prominence of indigoid photoswitches, mechanistic understanding of their excited state behavior and therefore rational design opportunities for photophysical properties are also much less developed compared to, for example, azobenzenes or stilbenes. By testing different substitution patterns, we were able to produce strongly beneficial property combinations in hemithioindigo, hemiindigo, or indigo photoswitches, for example, red-light responsiveness together with very high thermal bistability of the switching states. This is of particular importance for photopharmacological and biological applications of these switches to reduce the damage from high-energy light and to enable deep penetration of the light into tissues. An additional ground state twisting in hemithioindigo allowed us to control the type of light-induced bond rotation simply by the polarity of the solvent. With the aid of time-resolved spectroscopy and quantum yield measurements, we could show that in apolar cyclohexane exclusive double bond rotation takes place while in polar DMSO sole single bond rotation is observed. Such precise control over geometrical changes is of great interest for the construction of future sophisticated molecular machinery. In this field, we h...

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Section: Applicationsmentioning

confidence: 99%

Indigoid Photoswitches: Visible Light Responsive Molecular Tools

2018

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“…It is known as a chromophore for more than 100 years and was first described by Adolf von Baeyer in 1883 naming the compounds obtained from condensation of indoxylic acid and aldehydes “Indogenide” . Despite its facile synthesis, , established spectroscopic properties, − and relation to hemithioindigo − and aurone, − the photochemistry of hemiindigo is essentially unexplored especially with regard to applications as a photoswitch. As the absorption profile of unsubstituted hemiindigo resides partially in the visible part of the electromagnetic spectrum, the possibility of reversible double bond photoisomerization using exclusively visible light is highly tempting.…”

Section: Introductionmentioning

confidence: 99%

Hemiindigo: Highly Bistable Photoswitching at the Biooptical Window

et al. 2017

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Hemiindigo is a long known chromophore that absorbs in the blue part of the spectrum but has almost completely been ignored as potential photoswitch. Herein we show how the absorption of hemiindigo is shifted to the red part of the visible spectrum and how nearly perfect photoswitching can be achieved using blue or green and red light. Five derivatives were investigated giving very high isomeric yields in both switching directions, i.e. >90% E isomer after irradiation with 470 to 530 nm light and 99% Z isomer with 590 up to 680 nm light. At the same time the thermal bistability is extraordinarily high leading to half-lives of the pure isomeric states of up to 83 years at 25 °C. The herein developed photoswitches show photochromism in the visible enabling the two isomeric states to be distinguished by the naked eye. Substituted hemiindigos therefore constitute extremely promising new photoswitches with excellent properties for applications in biology, chemistry, or material sciences.

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“…21,27,43 For instance, while the reaction of the appropriate 3-oxoacid anilides with oxalyl A new route leading to dyestuffs 39, containing a pyrrolidine-2,3,5-trione moiety, was described by Katritzky. 44 The novel, colored indoxyl derivative 39 was prepared by reaction of 3,4-dichloro-N-phenylmaleinimide (38) and N-acyl indolin-3-one 37 (Scheme 12). The obtained compound is black in the solid state, but violet-reddish in solution.…”

Section: Synthesis Of Schiff Bases At C-6 Of Pyrrolidine-235-trionementioning

confidence: 99%

Pyrrolidinetrione Derivatives: Synthesis And Applications in Heterocyclic Chemistry

Zaleska¹,

Lis²

2001

Synthesis

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This review article, covering the literature from 1891 to 1999, deals with the methods of preparation of pyrrolidinetrione derivatives, emphasis being placed on methods of reasonable efficiency. A general applicability of these compounds as versatile building blocks in synthesis of fused heterocyclic systems is in focus. Pyrrolidine-2,3,4-trione Derivatives in the Synthesis of Anellated Nitrogen-Containing 5,5-Ring Systems 4 Hydrogenation of Pyrrolidine-2,3,5-triones 5 Su mmary

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Color and constitution. Part 8. Some novel dyestuffs containing indoxyl residues

Abstract: Novel dyes containing C‐likned indoxyl residues are prepared by two routes: (a) by the reaction of C‐electrophiles with N‐acetylindoxyl and (b) by the reaction of active methylene compounds with 2‐chloroindole‐3‐one. The visible absorption spectra are recorded and discussed.

Cited by 20 publications

References 15 publications

Indigoid Photoswitches: Visible Light Responsive Molecular Tools

Indigoid Photoswitches: Visible Light Responsive Molecular Tools

Hemiindigo: Highly Bistable Photoswitching at the Biooptical Window

Pyrrolidinetrione Derivatives: Synthesis And Applications in Heterocyclic Chemistry

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