Effects of alcohols on emission spectra of toluene-triethylamine mixtures in THF: Separation into polar and hydrogen-bonding interactions

Guobin Xie, Yoshimi Sueishi, Shunzo Yamamoto

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6 Citations (Scopus)

Abstract

The emission spectra of toluene (T)-triethylamine (TEA) systems were measured under conditions of steady-state illumination in some protic and aprotic solvent-THF mixtures. The fluorescence spectrum of the T-TEA system in THF could be separated into three component bands (band A at 279 nm (fluorescence of T), band B at 336 nm (fluorescence of TEA) and band C at 373 nm (emission from an intermolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. The decrease in the intensities of bands B and C is considered to be caused by the enhanced conversion of the exciplex to an ion-pair with increase in solvent polarity. The intensities of bands B and C also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of TEA with alcohols were estimated from the changes in the intensity of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be evaluated separately. The ratio of the hydrogen-bonding effect to the polar effect of alcohols was observed to increase with increasing vol.% of alcohol.

Original languageEnglish
Pages (from-to)449-456
Number of pages8
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume162
Issue number2-3
DOIs
Publication statusPublished - Mar 15 2004

Fingerprint

Toluene
toluene
Hydrogen bonds
emission spectra
alcohols
Alcohols
hydrogen
Fluorescence
interactions
Trichloroacetic acid
Trichloroacetic Acid
Protonation
Equilibrium constants
Acetonitrile
fluorescence
Hydrogen
polarity
Lighting
triethylamine
Ions

Keywords

  • Exciplex
  • Fluorescence
  • Hydrogen-bonding
  • Polar effect
  • Solvent effect

ASJC Scopus subject areas

  • Bioengineering
  • Physical and Theoretical Chemistry

Cite this

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title = "Effects of alcohols on emission spectra of toluene-triethylamine mixtures in THF: Separation into polar and hydrogen-bonding interactions",
abstract = "The emission spectra of toluene (T)-triethylamine (TEA) systems were measured under conditions of steady-state illumination in some protic and aprotic solvent-THF mixtures. The fluorescence spectrum of the T-TEA system in THF could be separated into three component bands (band A at 279 nm (fluorescence of T), band B at 336 nm (fluorescence of TEA) and band C at 373 nm (emission from an intermolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. The decrease in the intensities of bands B and C is considered to be caused by the enhanced conversion of the exciplex to an ion-pair with increase in solvent polarity. The intensities of bands B and C also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of TEA with alcohols were estimated from the changes in the intensity of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be evaluated separately. The ratio of the hydrogen-bonding effect to the polar effect of alcohols was observed to increase with increasing vol.{\%} of alcohol.",
keywords = "Exciplex, Fluorescence, Hydrogen-bonding, Polar effect, Solvent effect",
author = "Guobin Xie and Yoshimi Sueishi and Shunzo Yamamoto",
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TY - JOUR

T1 - Effects of alcohols on emission spectra of toluene-triethylamine mixtures in THF

T2 - Separation into polar and hydrogen-bonding interactions

AU - Xie, Guobin

AU - Sueishi, Yoshimi

AU - Yamamoto, Shunzo

PY - 2004/3/15

Y1 - 2004/3/15

N2 - The emission spectra of toluene (T)-triethylamine (TEA) systems were measured under conditions of steady-state illumination in some protic and aprotic solvent-THF mixtures. The fluorescence spectrum of the T-TEA system in THF could be separated into three component bands (band A at 279 nm (fluorescence of T), band B at 336 nm (fluorescence of TEA) and band C at 373 nm (emission from an intermolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. The decrease in the intensities of bands B and C is considered to be caused by the enhanced conversion of the exciplex to an ion-pair with increase in solvent polarity. The intensities of bands B and C also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of TEA with alcohols were estimated from the changes in the intensity of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be evaluated separately. The ratio of the hydrogen-bonding effect to the polar effect of alcohols was observed to increase with increasing vol.% of alcohol.

AB - The emission spectra of toluene (T)-triethylamine (TEA) systems were measured under conditions of steady-state illumination in some protic and aprotic solvent-THF mixtures. The fluorescence spectrum of the T-TEA system in THF could be separated into three component bands (band A at 279 nm (fluorescence of T), band B at 336 nm (fluorescence of TEA) and band C at 373 nm (emission from an intermolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. The decrease in the intensities of bands B and C is considered to be caused by the enhanced conversion of the exciplex to an ion-pair with increase in solvent polarity. The intensities of bands B and C also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of TEA with alcohols were estimated from the changes in the intensity of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be evaluated separately. The ratio of the hydrogen-bonding effect to the polar effect of alcohols was observed to increase with increasing vol.% of alcohol.

KW - Exciplex

KW - Fluorescence

KW - Hydrogen-bonding

KW - Polar effect

KW - Solvent effect

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