Effect of H-bond formation on the electronic spectra of some azo compounds derived from 3-amino-1,2,4-triazole

Abstract

Abstract. The UV-visibie spectra of some azo compounds derived from 3-amino-l,2,4-triazole and various active-methylene or active-hydrogen compounds have been investigated in organic solvents of different polarities. The spectral bands obtained are assigned to the possible electronic transitions. It was found that the azo compounds containing the acetylacetone moiety exist mainly in the hydrazone form, while those containing ethylcyanoacetate, c~ or [3-naphthol substituents exist in an azo ~ hydrazone tautomeric equilibrium in solution. The extra visible band exhibited in the spectra of o-hydroxyazo compound is assigned to an intermolecular electronic transition. The spectral shifts observed in the various organic solvents are discussed on the basis of the solute-solvent interaction through the formation of hydrogen bonds with different species. The variation of the absorbance with pH is employed to determine the acid dissociation constants.

Phosphoric acid densified red emissive carbon dots with a well-defined structure and narrow band fluorescence for intracellular reactive oxygen species detection and scavenging

“…22 The sharp signals at 9.1 and 4.0 ppm are attributed to the protons of P-OH and -NH-, respectively. 56,57 Hence, the MS and 1 H-nuclear magnetic resonance ( 1 H NMR) results for R-CDs also support the proposed model structure marked 5c-O/O-5c, which can be considered the basic units of R-CDs. These results indicate that R-CDs are formed by pyrophosphate traction Y-CD basic units.…”

“…S18, ESI†); the signal at 9.96 ppm corresponding to the P–O–P of pyrophosphate was clearly observed. 56 These results suggest that H 3 PO 4 may have played a traction role in the preparation of the R-CDs, which could be formed from two 2,3-diaminophenazine-like structures linked by the P–O–P bond.…”

A study on the spectral changes of reactive textile dyes and their implications for online control of dyeing processes

“…In general, azo dyes exist as the hydrazone form in polar solvents such water, but depend on the substitute groups in o ‐positon in relation to the azo bond. These tautomeric forms are structurally distinct compounds with the same chemical formulae (detected in spectral analysis) as in rapid equilibrium [19–22].…”

VOLTAMMETRIC BEHAVIOURS OF Zn(II) AND Ni(II) COMPLEXES WITH ACID RED 1 AT MERCURY ELECTRODE

“…The absorption maxima of AR 1 and its Zn(II) and Ni(II) complexes are shown in Table 1. According to previous studies 36,38 , the assignments for absorption maxima were made (Table 1). In the literature, the main adsorption band of AR 1 was characterized by peaks at 506 and 531 nm 39 .…”