Spectrophotometric determination of microamounts of yttrium with 1-amino-4-hydroxyanthraquinone

Saleh, Magda S.

doi:10.1007/bf00807151

Cited by 5 publications

(1 citation statement)

References 13 publications

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“…Therefore, it was believed that sodium acetate ionized only the 2-hydroxy group Table 4. p l ,p*-Absorption bands of purpurin dianions [26] ethanol, …”

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confidence: 99%

A Quantum-Chemical and Correlation Study of the Ionization of Purpurin

2005

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Anthraquinoid tautomers participate in the ionization of purpurin. The tautomerism takes place in both ground and excited states of the molecules; the excited state is more sensitive to the tautomerism. The solvation and ionization shift the tautomeric equilibria. In the experimental absorption spectra of purpurin, the major bands correspond to the 9,10-, 1,4-, and 1,10-anthraquinoid tautomers; anions with the 9,10-anthraquinoid structure are not detected. The position and intensity of the p,p* bands, and also the quantumchemical parameters linearly correlate with the degree of ionization of purpurin.Anthraquinones exhibit inexhaustible theoretical and applied potential. They are used as natural and synthetic dyes, pigments, luminophores, biologically active substances, drugs, chemicals for information storage and processing, catalysts and inhibitors of chemical processes, sensitizers for photochemical reactions, analytical reagents, and indicators [1].For a long period, the chemistry of anthraquinones developed exclusively as the chemistry of 9,10-anthraquinones. In the past decades, there has been a growing interest in isomeric anthraquinones containing carbonyl groups in other positions of the anthracene core [2, 3]; these compounds often exhibit unique chemical properties. Studies of photochemical processes accompanied by tautomeric transformations of anthraquinoid structures (see, e.g., [4]) revealed importance of isomeric anthraquinones and opened prospects for the development of new processes.We found [5,6] that the electronic absorption spectra of dihydroxyanthraquinones contain bands assignable to states with the prevalent contribution of different tautomeric anthraquinoid resonance structures. Thus, the role of isomeric anthraquinones is considerably more important than it was believed for a long time. As a result, we were able to interpret the complex absorption spectra of quinizarin and its anions [7], alizarin anions [8], and metal complexes of dihydroxyanthraquinones [9,10]. These studies completed long-term discussions concerning the structure of red alizarinates [10] and posed the question of revision of the results of numerous studies on the ionization of hydroxyanthraquinones, initiated by their use as reagents for the determination of metals and antibiotic model compounds. In this study we examined the ionization of 1,2,4-trihydroxy-9,10-anthraquinone (purpurin), one of the most important compounds of this series.

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“…Therefore, it was believed that sodium acetate ionized only the 2-hydroxy group Table 4. p l ,p*-Absorption bands of purpurin dianions [26] ethanol, …”

mentioning

confidence: 99%