Color prediction from first principle quantum chemistry computations: a case of alizarin dissolved in methanol

Abstract

The electronic spectrum of alizarin (AZ) in methanol solution was measured and used as reference data for color prediction. The visible part of the spectrum was modelled by different DFT functionals within the TD-DFT framework. The results of a broad range of functionals applied for theoretical spectrum prediction were compared against experimental data by a direct color comparison. The tristimulus model of color expressed in terms of CIE XYZ and CIE Lab parameters was applied both to experimental and predicted spectra. It was found that the HSE03 method along with the 6-31G(d,p) basis set provides the most accurate color prediction, much better than other commonly used functionals such as B3LYP, CAM-B3LYP or PBE0. Besides, the influence of potential errors, introduced by theoretical predictions on color estimation, was examined for different wavelengths. The obtained results showed that color prediction is significantly dependent on the type of basis set and functional applied. The proposed methodology provides a simple, straightforward and more reliable way of theoretical protocols validation than just a comparison of experimental and estimated values of maximum absorbance wavelength.

Electrochemical Behaviour of Anthraquinone Dyes in Non Aqueous Solvent Solution.

“…An absorption band at 550 nm is shown in the UV-vis spectrum of the violet solution. This absorption maximum is assigned to the AH ̶ specie [12][13][14]. This experiment confirms the incorporation of the second step (C1 + C6) in Scheme 4.…”

“…Alizarin exists in three forms of different colours, namely the protonated species (neutral non-dissociated AH 2 in Scheme 2) and two deprotonated species corresponding to the monoanion (AH − in Scheme 2) and dianion (A 2− in Scheme 2). The absorption maximum of the neutral non-dissociated form is located at 430 nm, the monoanionic form is characterized by an absorption maximum at around 530 nm while the dianionic form is represented by two superimposed bands in the range from 570 nm to 620 nm [11][12][13][14][15][16][17]. The colour change of alizarin is modelled based on simple protocol within TD-DFT framework [13].…”

Predicting solvatochromic shifts and colours of a solvated organic dye: The example of nile red

“…In order to obtain a prediction of the colour of a dye in solution from a TDDFT absorption spectrum, we follow the method of tristimulus colorimetry theory, as outlined by Cysewski et al [45] and Baroni et al [14] in the context of TDDFT. We define the intensity I trans (λ) of light transmitted through a sample of the dye in solution via…”

Synthesis, characterization, photo physical properties of two isomeric forms of an azo dye supported by DFT calculations and their interaction with DNA

“…Density Functional Theory (DFT), an important tool to obtain better insights into the geometry, electronic structure and optical properties of molecular systems was used to explain the observed photo‐physical properties …”

“…[20][21][22][23] Density Functional Theory (DFT), an important tool to obtain better insights into the geometry, electronic structure and optical properties of molecular systems was used to explain the observed photo-physical properties. [24,25] The ability to computationally predict isomerization from a structure would be highly advantageous for the customized design of molecules for specific applications.Among the computational methods for calculating the electronic structure of molecules, DFT is most accurate in reproducing the experimental values of molecular geometry. DFT has been widely used to study cis-trans isomerization of azo-aromatic systems.…”