Cooperative intramolecular hydrogen bonding induced azo-hydrazone tautomerism of azopyrrole: Crystallographic and spectroscopic studies

Jin-Huan, Chen; Yin, Zhenming

doi:10.1016/j.dyepig.2013.10.036

Cited by 29 publications

(8 citation statements)

References 33 publications

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“…The N-heterocyclic compounds chosen were all N-methylated to prevent rapid Z-E thermal isomerisation through a tautomerisation-isomerisation mechanism. 29,31 Arylazopyrroles 2 and 5 and Figure 2: UV/vis spectra of azoheteroarenes in acetonitrile. Inset: repeated photoswitching cycles of azopyrazole 11.…”

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confidence: 99%

Arylazopyrazoles: Azoheteroarene Photoswitches Offering Quantitative Isomerization and Long Thermal Half-Lives

et al. 2014

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Arylazopyrazoles, a novel class of five-membered azo photoswitches, offer quantitative photoswitching and high thermal stability of the Z isomer (half-lives of 10 and ∼1000 days). The conformation of the Z isomers of these compounds, and also the arylazopyrroles, is highly dependent on the substitution pattern on the heteroarene, allowing a twisted or planar geometry, which in turn has a significant impact on the electronic spectral properties of the compounds.

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Arylazopyrazoles: Azoheteroarene Photoswitches Offering Quantitative Isomerization and Long Thermal Half-Lives

et al. 2014

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“…In addition to impacting the conformation of these systems (vide supra), N-methylation of azole azoheteroaryl photoswitches is required to avoid very fast thermal isomerisation of the Z isomer through tautomerisation. 25,26 Reductive coupling of 4 using zinc in aqueous ammonium chloride, 27 gave the required photoswitch 1.…”

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Photoswitchable basicity through the use of azoheteroarenes

2016

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Azoheteroarene photoswitches offer functional advantages over their more conventional azobenzene counterparts by virtue of their heteroaromatic ring(s). Here we report that azobis(2-imidazole) functions as a photoswitchable base due to the additional proton stabilisation that is possible in the protonated Z isomer, facilitated by the basic imidazole nitrogens. This thermodynamic difference in stability corresponds to a 1.3 unit difference in pK(a) values between the E and Z isomers. This pK(a) difference can be used to reversibly control solution pH.

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“…And exactly the opposite is stated in the abstract of the original paper dealing with compounds 48/49. 9 It is also evident from Scheme 5 in the review, where the hydrazone form is stabilized in chloroform, while DMSO shis the equilibrium towards the azo tautomer. Actually there is no keto-enol, but azo-hydrazone tautomerism in this pair of compounds.…”

Section: Fundamental Principles Of Tautomerismmentioning

confidence: 96%

Comment on “Spectroscopic studies of keto–enol tautomeric equilibrium of azo dyes” by M. A. Rauf, S. Hisaindee and N. Saleh, RSC Adv., 2015, 5, 18097

2015

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Cooperative intramolecular hydrogen bonding induced azo-hydrazone tautomerism of azopyrrole: Crystallographic and spectroscopic studies

Cited by 29 publications

References 33 publications

Arylazopyrazoles: Azoheteroarene Photoswitches Offering Quantitative Isomerization and Long Thermal Half-Lives

Arylazopyrazoles: Azoheteroarene Photoswitches Offering Quantitative Isomerization and Long Thermal Half-Lives

Photoswitchable basicity through the use of azoheteroarenes

Comment on “Spectroscopic studies of keto–enol tautomeric equilibrium of azo dyes” by M. A. Rauf, S. Hisaindee and N. Saleh, RSC Adv., 2015, 5, 18097

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