Tautomerism of Aromatic Azo-compounds

Abstract

PACS. 05.45 -Theory and models of chaotic systems. PACS. 33.80B -Level crossing and optical pumping.PACS. 74.50 -Proximity effects, tunnelling phenomena, and Josephson effect.Abstract. -We study the quantal dynamics of a harmonically driven quartic double well in the presence of dissipation. A master equation for the reduced density operator is derived in the Floquet representation. In the classical limit, this system corresponds to a Duffing oscillator with Ohmic damping. We present numerical results for the transient time evolution and for the stationary sate. The influence of the weak dissipation on interference effects in the context of driven tunnelling is discussed on the basis of these 'results. We find that the coherent suppression of tunnelling can be stabilized by reservoir-induced noise for a suitably chosen temperature.

Absorption UV–Vis Spectroscopy and Chemometrics: From Qualitative Conclusions to Quantitative Analysis

“…This approach was mathematically developed by Bershtein and Ginsburg [12] and later used for the analysis of the tautomeric equilibrium in 2 [13]. The main problem here is to find real individual areas of absorbance.…”

Quantum mechanical investigation of the tautomerism in the azo dye Sudan III

“…Aromatic azo derivatives constitute a broad class of compounds with interesting optical properties. Their practical and theoretical importance has been reflected in the great number of studies of structure and spectroscopic investigations of analogous chemical systems 1–23. Despite the electronic effects of the substituents attached to the phenyl rings, some physical‐chemical processes are directly related to the optical characteristics of azobenzene compounds.…”

Analytical Azo Coupling Reactions: A Quantum-Chemical Consideration

“…The precipitate of the azo compound formed when the reaction proceeded in an aqueous medium was isolated by preparative techniques [7,8]. The absorption band with λ max = 480 nm in the electronic absorption spectrum of an alkaline solution of the isolated amino azo compound is characteristic of the nonprotonated azoic form [14,15,71]. In acidic aqueous and micellar media λ max = 560 nm [7,8], which corresponds to the quinone-hydrazone form [15].…”

“…The quinoid structure of the analytical form is experimentally supported by the presence of a band with an absorption maximum at 550 nm [15] in the electronic absorption spectrum of the nitrite ion-1-aminonaphthalene-sulfanilic acid-anionic surfactant reaction system [9].…”

“…Amino azo compounds, which are the products of both the analytical reactions mentioned above, can in principle manifest azo-quinone hydrazone tautomerism [15].…”