Comparison of several protocols for the computational prediction of the maximum absorption wavelength of chrysanthemin

Abstract

UV-Vis spectra were calculated using time-dependent density functional theory for the chrysanthemin pigment, which is used as natural dye in dye sensitized solar cells. To this end, we studied four different calculation protocols in order to obtain the best approximation according to the maximum absorption wavelength (λmax) of the experimental spectrum. Furthermore, the optimized geometry, highest occupied molecular orbitals, lowest unoccupied molecular orbitals and electron density were calculated and analyzed. Several chemical models were used with and without the presence of the chlorine atom: the chosen functionals, B3LYP, PBE0 and the M06 family, represent various approximations with different fractions of Hartree-Fock exchange energy. These functionals were combined with the 6-31+G (d), 6-311+G (d) and the MIDIX+basis sets. All of these calculation protocols proved a good option, though the B3LYP/MIDIX+chemistry model was the best for predicting the λmax value, using the equilibrium calculation protocol (M1a) in the presence of chlorine.

Theoretical insight of alpha amino acid phenylalanine adsorption on pristine and decorated fullerenes

“…However, results from the M062X functional yields a change about 2.92 eV. This difference in the gap energy arises from the fact that unlike B3LYP functional M062X overestimates E g values (Soto-Rojo et al, 2014).…”

A Comparative Study on the Photophysical Properties of Anthocyanins and Pyranoanthocyanins

“…The anthocyanins studied are represented in the form of the flavylium cation (Figure 1), which is the most stable anthocyanin isomer.A schematic overview of the different substitution patterns that were considered is shown in Figure 1a nd labeled according to Ta ble S1 (in the Supporting Information). The library consists of two 3-deoxyanthocyanidins (apigeninidin (ap) and luteolinidin (lt), 1-2), the six most commonly occurring anthocyanidins (cyanidin (cy), delphinidin (dp), malvidin (mv), pelargonidin (pg), peonidin (pn), and petunidin (pt), 3-8), anthocyanins (3-glucosides of the six anthocyanidins, 9-14), acylated anthocyanins (acylation at the glucose moiety with acetic acid (15)(16)(17)(18)(19)(20), caffeic acid (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), and coumaric acid (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)), pyranoanthocyanins (pyruvic acid (45)(46)(47)(48)(49)(50), acetaldehyde (51)(52)(53)(54)(55)(56), vinylphenol (57-62), and vinylcate...…”

“…These aromatic co-pigments possess UV-absorbing and electron-donating properties, which improvet he compounds' light stability. [5] In this section, the influence of acylation (R 6'' in Figure 1) by acetic acid (15)(16)(17)(18)(19)(20), caffeic acid (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), and p-coumaric acid (33-44)a sc o-pigments will be discussed.F urthermore, the effect of cis and trans isomerization of the two aromatic acids on the UV/Vis spectra is also considered.…”

“…As aromatic acyls inducei ntramolecular co-pigmentation within acylated anthocyanins, the different types and strengths of the intramolecular interactions are further investigated. To find the minimab etween cis and trans isomerization,t he rotational barriers of each individual caffeoyl (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)o rc oumaroyl (33-44)a cylated anthocyanin were determined. In the gas phase, the cis/trans barrierf or caffeoyl acylated anthocyanins is less than 6kJmol À1 (Figure S5 in the Supporting Information), whereas the barrierf or coumaroyl acylated anthocyanins is 11 kJ mol À1 (Figure S6 in the Supporting Information), both in favor of the trans conformer.T he barriers for caffeoyl and coumaroyl acylated anthocyanins in methanolw ithS MD as solvation model were about 10 kJ mol À1 ,w hereas in water the caffeoyl and coumaroyla cylated conformers showed an average gap of 4.4 kJ mol À1 and 11 kJ mol À1 ,r espectively (Table S9 in the Supporting Information).…”

“…[16b] Similar topics are also studied for pyranoanthocyanins:g eometry, [21] antioxidant activity, [22] UV/Vis spectra, [23] and acidity constants. [24] However,t he current literature about the photophysical properties of anthocyaninsa nd pyranoanthocyanins is quite scattered, with av ariety of methods such as calculations within the gas phase [25] or different solvation models( i.e.,P CM, C-PCM,C OSMO or SMD), different levels of theory,a nd scattered datasets such as single compound data [26] or synthetically modifieda nthocyaninst oi nvestigate the influence of the substituento nt he color change. [23a, 27] Herein, as ystematic analysis was performed by evaluating three functionals (B3LYP,C AM-B3LYP,a nd PBE0) for al arge set of naturallyo ccurring anthocyanin-based compounds along with structure elucidationst o clarify the hypso-or bathochromic shifts observed within the experimental literature data.…”