Additivity of substituent effects on the visible absorption spectra of some heteroarylazo compounds: the influence of solvent

Michael G. Hutchings, Andrew Mills

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Pronounced solvatochromic shifts are observed in the visible spectra of two series of heteroarylazobenzene derivatives based on m-acetylamino- and m-methyl-N,N-diethylaniline, measured in various solvents. The heteroaryl azo component of these dyes can be viewed as a thiophene ring substituted by cyano, nitro, alkoxycarbonyl, or ring aza (to give thiazole and isothiazole derivatives). Free-Wilson analysis has shown that the influence of each of the substituents is constant across all molecules within the two series for a given solvent. However, the substituent increments vary between different solvents and correlate with the Kamlet-Taft dipolarity/polarisability parameter pi* of the solvents. There appears to be no intuitive explanation for the relative solvent variation of different substituents, but Onsager theory suggests sensitivity to the relative size and shape of the dyes. Visible absorption maxima are predicted for unknown heteroarylazo compounds related to those studied.
LanguageEnglish
Pages23-31
Number of pages8
JournalDyes and Pigments
Volume47
Issue number1-2
DOIs
Publication statusPublished - 4 Oct 2000

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Absorption spectra
Coloring Agents
Dyes
Derivatives
Thiazoles
Thiophenes
Thiophene
Molecules

Keywords

  • heteroarylazo
  • solvatochromism
  • substituent additivity
  • Kamlet-Taft
  • Onsager theory

Cite this

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title = "Additivity of substituent effects on the visible absorption spectra of some heteroarylazo compounds: the influence of solvent",
abstract = "Pronounced solvatochromic shifts are observed in the visible spectra of two series of heteroarylazobenzene derivatives based on m-acetylamino- and m-methyl-N,N-diethylaniline, measured in various solvents. The heteroaryl azo component of these dyes can be viewed as a thiophene ring substituted by cyano, nitro, alkoxycarbonyl, or ring aza (to give thiazole and isothiazole derivatives). Free-Wilson analysis has shown that the influence of each of the substituents is constant across all molecules within the two series for a given solvent. However, the substituent increments vary between different solvents and correlate with the Kamlet-Taft dipolarity/polarisability parameter pi* of the solvents. There appears to be no intuitive explanation for the relative solvent variation of different substituents, but Onsager theory suggests sensitivity to the relative size and shape of the dyes. Visible absorption maxima are predicted for unknown heteroarylazo compounds related to those studied.",
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Additivity of substituent effects on the visible absorption spectra of some heteroarylazo compounds: the influence of solvent. / Hutchings, Michael G.; Mills, Andrew.

In: Dyes and Pigments, Vol. 47, No. 1-2, 04.10.2000, p. 23-31.

Research output: Contribution to journalArticle

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AU - Hutchings, Michael G.

AU - Mills, Andrew

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N2 - Pronounced solvatochromic shifts are observed in the visible spectra of two series of heteroarylazobenzene derivatives based on m-acetylamino- and m-methyl-N,N-diethylaniline, measured in various solvents. The heteroaryl azo component of these dyes can be viewed as a thiophene ring substituted by cyano, nitro, alkoxycarbonyl, or ring aza (to give thiazole and isothiazole derivatives). Free-Wilson analysis has shown that the influence of each of the substituents is constant across all molecules within the two series for a given solvent. However, the substituent increments vary between different solvents and correlate with the Kamlet-Taft dipolarity/polarisability parameter pi* of the solvents. There appears to be no intuitive explanation for the relative solvent variation of different substituents, but Onsager theory suggests sensitivity to the relative size and shape of the dyes. Visible absorption maxima are predicted for unknown heteroarylazo compounds related to those studied.

AB - Pronounced solvatochromic shifts are observed in the visible spectra of two series of heteroarylazobenzene derivatives based on m-acetylamino- and m-methyl-N,N-diethylaniline, measured in various solvents. The heteroaryl azo component of these dyes can be viewed as a thiophene ring substituted by cyano, nitro, alkoxycarbonyl, or ring aza (to give thiazole and isothiazole derivatives). Free-Wilson analysis has shown that the influence of each of the substituents is constant across all molecules within the two series for a given solvent. However, the substituent increments vary between different solvents and correlate with the Kamlet-Taft dipolarity/polarisability parameter pi* of the solvents. There appears to be no intuitive explanation for the relative solvent variation of different substituents, but Onsager theory suggests sensitivity to the relative size and shape of the dyes. Visible absorption maxima are predicted for unknown heteroarylazo compounds related to those studied.

KW - heteroarylazo

KW - solvatochromism

KW - substituent additivity

KW - Kamlet-Taft

KW - Onsager theory

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