Photophysical behaviour of 2,6-diaminoanthraquinone in different solvents and at various pH

The absorption and fluorescence spectral properties of 2,6-diaminoanthraquinone (DAAQ) have been investigated in a series of organic solvents of different polarity and in aqueous solutions with H o/pH/ H_ in the range −10 to 17. The Stokes shift of DAAQ is correlated with various polarity scales. Th...

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Veröffentlicht in:	Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2007-11, Vol.68 (3), p.651-655
Hauptverfasser:	Siva Kumar, P., Kothai Nayaki, S., Swaminathan, M.
Format:	Artikel
Sprache:	eng
Schlagworte:	2,6-Diaminoanthraquinone Anthraquinones - chemistry Cyclohexanes - chemistry Hydrogen bonding interactions Hydrogen-Ion Concentration Light Solvent relaxation Solvents - chemistry Spectrometry, Fluorescence
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Zusammenfassung:	The absorption and fluorescence spectral properties of 2,6-diaminoanthraquinone (DAAQ) have been investigated in a series of organic solvents of different polarity and in aqueous solutions with H o/pH/ H_ in the range −10 to 17. The Stokes shift of DAAQ is correlated with various polarity scales. The study reveals the fluorescence of DAAQ dication is red shifted on protonation. The abnormal fluorescence of DAAQ dication is found to be due to large solvent relaxation in polar medium. The acidity constants for various prototropic reactions in S o and S 1 states are determined and discussed.
ISSN:	1386-1425
DOI:	10.1016/j.saa.2006.12.042