Highly Soluble and Green Indigo Dyes: 4,4′,7,7′‐Tetraalkoxy‐5,5′‐diaminoindigotins

Voß, Gundula; Gradzielski, Michael; Heınze, Jürgen; Reinke, Helmut; Unverzagt, Carlo

doi:10.1002/hlca.200390156

Cited by 16 publications

(15 citation statements)

References 40 publications

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“…Nevertheless a brief comment on the solvent dependence is useful since these well-known polar molecules seem to respond to the polarity of the media. [6,12] If one takes the dielectric constant of the media (e) as indicative of the solvent polarity, one can observe that in general the absorption wavelength maxima redshifts with the increase in the e value [e 25 8C…”

Section: Discussionmentioning

confidence: 99%

“…7,7'-Dimethoxy-4,4-dinonyloxyindigotin [2-(7-methoxy-4-nonyloxy-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-7-methoxy-4-nonyloxyindol-3-one; 5]: Compound 5 was prepared from 3-methoxy-2-nitro-6-nonyloxybenzaldehyde and acetone. [6] 5,5',…”

Section: Methodsmentioning

confidence: 99%

“…5,5'-Diamino-4,4'-dihexyloxy-7,7'-dimethoxyindigotin [2-(5-amino-4-hexyloxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-5-amino-4-hexyloxy-7-methoxyindol-3-one; 7]: Compound 7 was prepared by reduction of 4,4'-dihexyloxy-7,7'-dimethoxy-5,5'-dinitroindigotintin (from 2-hexyloxy-5-methoxy-3,6-dinitrobenzaldehyde, acetone, and KOH) with sodium dithionite (Na 2 S 2 O 4 ). [6] 5,5'-Diamino-4,4'-dibutoxy-7,7'-dimethoxyindigotin [2-(5-amino-4-butoxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-5-amino-4-butoxy-7-methoxyindol-3-one; 8]: Compound 8 was prepared by treatment of 4,4'-dibutoxy-7,7'-dimethoxy-5,5'-dinitroindigotin (from 2-butoxy-5-methoxy-3,6-dinitrobenzaldehyde, acetone, and KOH) with sodium dithionite (Na 2 S 2 O 4 ). [6] 4,4'-Dibutoxy-7,7'-dimethoxy-5,5'-dinitroindigotin [2-(4-butoxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-4-butoxy-7-methoxy-5-nitroindol-3-one; 9]: Compound 9 was prepared from 2-butoxy-5-methoxy-3,6-dinitrobenzaldehyde and acetone/KOH.…”

Section: Methodsmentioning

confidence: 99%

“…[6] 5,5'-Diamino-4,4'-dibutoxy-7,7'-dimethoxyindigotin [2-(5-amino-4-butoxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-5-amino-4-butoxy-7-methoxyindol-3-one; 8]: Compound 8 was prepared by treatment of 4,4'-dibutoxy-7,7'-dimethoxy-5,5'-dinitroindigotin (from 2-butoxy-5-methoxy-3,6-dinitrobenzaldehyde, acetone, and KOH) with sodium dithionite (Na 2 S 2 O 4 ). [6] 4,4'-Dibutoxy-7,7'-dimethoxy-5,5'-dinitroindigotin [2-(4-butoxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-4-butoxy-7-methoxy-5-nitroindol-3-one; 9]: Compound 9 was prepared from 2-butoxy-5-methoxy-3,6-dinitrobenzaldehyde and acetone/KOH. [6] Indigo, indirubin, indigocarmine, and Tyrian purple were obtained as previously reported.…”

Section: Methodsmentioning

confidence: 99%

“…[6] 4,4'-Dibutoxy-7,7'-dimethoxy-5,5'-dinitroindigotin [2-(4-butoxy-7-methoxy-5-nitro-1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-4-butoxy-7-methoxy-5-nitroindol-3-one; 9]: Compound 9 was prepared from 2-butoxy-5-methoxy-3,6-dinitrobenzaldehyde and acetone/KOH. [6] Indigo, indirubin, indigocarmine, and Tyrian purple were obtained as previously reported. [2] The solvents used, benzene, dioxane and N,N-dimethylformamide (DMF), were of spectroscopic or equivalent grade.…”

Section: Methodsmentioning

confidence: 99%

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Spectral and Photophysical Studies of Substituted Indigo Derivatives in Their Keto Forms

et al. 2006

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The spectral and photophysical properties of indigo derivatives with di‐, tetra‐, and hexa‐substitution in their neutral (keto) form are investigated in solution. The study comprises absorption and emission spectra, together with quantitative measurements of quantum yields of fluorescence (ϕF) and singlet oxygen formation (ϕΔ) and fluorescence lifetimes. The energy difference between the HOMO and LUMO orbitals is dependent on the degree (number of groups) and relative position of substitution. The ϕF and ϕΔ values were found to be very low ≤10−3. Because of the absence of transient triplet–triplet signal, the intersystem crossing yields (ϕT) were estimated by assuming that all the triplet states formed give rise to singlet oxygen formation, that is, ϕΔ≈ϕT . It was then possible from ϕIC=1−ϕF−ϕT to estimate the S1∼∼→S0 internal conversion yields and thus, with the other data, to determine the rate constants for all decay processes. From these, several conclusions are drawn. Firstly, the radiationless rate constants, kNR , clearly dominate over the radiative rate constants, kF , (and processes). Secondly, the main deactivation channel for the compounds in their keto form is the radiationless S1∼∼→S0 internal conversion process. Finally, although the changes are relatively small, internal conversion yield seems to be independent of the overall pattern of substitution. A more detailed investigation of the decay profiles with collection at the blue and red emission of the fluorescence band of indigo and one di‐substituted indigo reveals the decays to be bi‐exponential and that at longer emission wavelengths these appear to be associated with both rise and decay times indicating that two excited species exist, which is consistent with a keto‐excited form giving rise (by fast proton transfer) to the enol‐form of indigo. Evidence is presented which supports the idea that intramolecular (and possibly some intermolecular) proton transfer can explain the high efficiency of internal conversion in indigo.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Spectral and Photophysical Studies of Substituted Indigo Derivatives in Their Keto Forms

et al. 2006

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A Blueprint for Transforming Indigos to Photoresponsive Molecular Tools

Huang

Hecht

2023

Chemistry A European J

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Indigo, one of the most ancient and abundant dyes in human history, has recently emerged as a potential functional motif due to its intriguing photochemical properties. This review aims to provide insights into both the preparation of these molecules and their utilization in molecular systems. First, the synthesis of the indigo core as well as available methods to derivatize indigo are described to outline synthetic strategies to build the desired molecular structures. Then, the photochemical behavior of indigos is discussed, with particular focus on E-Z photoisomerization and photoinduced electron transfer. Connections between the molecular structures and their photochemical properties are highlighted and serve as guiding principles for designing indigos to be applied as photoresponsive tools.

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Characterization of the Excited States of Indigo Derivatives in their Reduced Forms

2010

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A comprehensive characterization of the electronic spectral and photophysical properties of the leuco (reduced) form of several indigo derivatives, including indigo and Tyrian Purple, with di-, tetra-, and hexa-substitution, was obtained in solution. The characterization involves absorption, fluorescence, and triplet-triplet absorption spectra, together with quantitative measurements of quantum yields of fluorescence, phi(F) (0.46-0.04), intersystem crossing, phi(Tau) (0.013-0.034), internal conversion, phi(IC), and the corresponding lifetimes. The position and degree of substitution promote differences in the spectral and photophysical properties displayed by the investigated leuco derivatives. The phi(F) values are about two orders of magnitude higher than those previously obtained for the corresponding keto forms. Also in contrast with the behavior found for the keto forms, the S(1) approximately approximately -->T(1) intersystem crossing is an efficient route for the excited-state deactivation channel. These findings strengthen the fact that, in contrast to keto indigo where the internal conversion dominates the deactivation of the excited-state, with leuco indigo (and derivatives), the excited state deactivation involves competition between internal conversion, triplet state formation, and fluorescence. A time-resolved investigation of one of the compounds in glycerol showed the presence of a photoisomerization process.

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Highly Soluble and Green Indigo Dyes: 4,4′,7,7′‐Tetraalkoxy‐5,5′‐diaminoindigotins

Cited by 16 publications

References 40 publications

Spectral and Photophysical Studies of Substituted Indigo Derivatives in Their Keto Forms

Spectral and Photophysical Studies of Substituted Indigo Derivatives in Their Keto Forms

A Blueprint for Transforming Indigos to Photoresponsive Molecular Tools

Characterization of the Excited States of Indigo Derivatives in their Reduced Forms

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