Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution

Abstract

Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space.

Fabrication of Carboxymethyl Cellulose/Agar-Based Functional Films Hybridized with Alizarin and Grapefruit Seed Extract

“…Alizarin in its neutral state exhibits maximum absorption at ∼430 nm. The absorption peaks in the first and second anion forms shift to ∼550 and ∼570–620 nm in red, which are responsible for the pH-sensitive color change properties of alizarin. , The pH-dependent color variation of alizarin and the alizarin-added color indicator film (CMC/agar/Alz/GSE film) is shown in Figure a,b. The alizarin solution was yellow at pH 2, turned pale yellow and dark yellow at pH 4 and 5, respectively, and turned brighter pink at pH 7.…”

Modeling the Physicochemical Properties of Natural Deep Eutectic Solvents

“…The solubility of rutin also showed improvements in NADES based on urea, sugar, organic acids, and choline chloride compared with water . The presence of basic sites in the NADES leads to increased solubility due to the acidic properties of the rutin …”

“…Jeliński et al. used the COSMO‐RS methodology for the screening of DES for the solvation of rutin by predicting the solubility . Their applied model also took into consideration the possible ionic and neutral forms of the HBA.…”

Materials science challenges in paintings

“…When considering dyeing molecules that have been used since Antiquity for synthesizing lake pigments by their precipitation or adsorption onto insoluble and white salts, calculations of their interaction with light can be obtained from first principles and density-functional theory (DFT) approach, as demonstrated for alizarin and its alkali metal complex compounds in a solvent. 24 Colour analysis validates the constituents and the geometrical structures of the model complexes used for the calculations.…”