A Comparative Study on the Photophysical Properties of Anthocyanins and Pyranoanthocyanins

Abstract

Anthocyanins and pyranoanthocyanins are flavonoids that are present in various food products (e.g., fruit, vegetables, wine, etc.). The large chemical diversity amongst these molecules leads to compound‐specific properties such as color and stability towards external conditions. These properties are also attractive for food and non‐food applications. The photophysical experimental characterization is not easy as this generally demands advanced analytical techniques along with optimized separation procedures. Molecular modeling can provide insights into the fundamental understanding of the photophysical properties of these compounds in a uniform way for a broad set of compounds. However, the current literature is quite fragmented on this topic. Herein, a large set of 140 naturally derived anthocyanins was evaluated in a systematic way with three functionals (B3LYP, PBE0, and CAM‐B3LYP). The accuracy of these functionals was determined with experimental literature λmax,vis values. In addition to λmax,vis values, time‐dependent (TD)‐DFT calculations also provided oscillator strengths, molar absorption coefficients, and orbital energies, which define whether specific natural anthocyanin‐based compounds can be deployed in food and non‐food applications such as food additives/colorants, textile dyeing, analytical standards, and dye‐sensitized solar cells (DSSCs).

Natural and Synthetic Flavylium-Based Dyes: The Chemistry Behind the Color

“…The presence of the catechol unit was shown to be essential for the efficient electron injection of the dye into TiO 2 semiconductors since carboxylic units showed a deleterious effect during electron injection due to their electron withdrawing character . Recently, the orbital energies obtained from vertical excitations in TD-DFT calculations of a series of anthocyanins were claimed to be a screening method to provide complementary information to experimental data in DSSCs …”

“…299 Recently, the orbital energies obtained from vertical excitations in TD-DFT calculations of a series of anthocyanins were claimed to be a screening method to provide complementary information to experimental data in DSSCs. 300…”

Phenolic compounds related to heartwood coloration of Millettia pendula

“…The effect of different B-ring substituents on absorption wavelengths has been investigated in the field of anthocyanins in detail. The presence of electrondonating groups such as methoxy and hydroxy groups increases the number of electrons involved in the conjugated system, resulting in a long wavelength shift of the absorption (Zhao et al 2020;Phan et al 2021). Besides, an increase in the dihedral angle between the A and C rings and the B ring due to steric hindrance also contributes to the long wavelength shift in absorption (Torskangerpoll et al 1999).…”