Photosynthetic Pigments with Potential for a Photosynthetic Antenna: A DFT Analysis

Abstract

Geometrical and electronic properties of the main photosynthetic pigments in higher plants such as chlorophylls and xanthophylls were studied to find potential candidates that were able to participate in an eventual zeolite-dye artificial antenna. CRDFT (chemical reactivity density functional theory) and TD-DFT (time-dependent DFT) methods were employed in ground-state and excited-state calculations, respectively. The evaluated electronic properties at the gas phase included (a) energies such as HOMO-LUMO band gap (H-L, ranging from 2.168 to 2.504 eV), adiabatic ionization potential (I, ranging from 5.964 to 7.207 eV), and adiabatic electronic affinity (A, ranging from 2.176 to 2.741 eV); (b) global chemical reactivity indexes such as electronegativity (χ, ranging from 4.121 to 4.974 eV), hardness (η, ranging from 1.812 to 2.233 eV), electrophilicity index (ω, ranging from 4.365 to 5.541 eV), and electroaccepting-electrodonating powers (ω+, ranging from 1.671 to 2.115 eV, and ω−, ranging from 4.375 to 5.273 eV); (c) electron-hole reorganization energies (λ, ranging from 0.225 to 0.519 eV and ranging from 0.168 to 0.425 eV, respectively) and electron-hole extraction potentials (EEP, ranging from 2.570 to 2.966 eV, and HEP, ranging from 5.538 to 7.012 eV, respectively); and (d) local chemical reactivity indexes like condensed Fukui functions (fk), condensed dual descriptor (f2r), and condensed local softness (sk). These electronic properties allowed the association between molecules and reactivity-selectivity criteria, under the context of charge transfer and electronic transitions. Also, the aforementioned electronic properties were determined for combinations made with the selected molecules (β-cryptoxanthin and zeaxanthin) and 5 solvents (n-hexane, diethyl ether, acetone, ethanol, and methanol) with upward dielectric constants (ε). From frequency calculations, IR spectra were obtained for combinations. Finally, excited-state computations were carried out to acquire UV-Vis spectra of the combinations. We conclude that the selection of dyes is controlled mainly by geometrical constraints rather than by electronic properties.

Theoretical FRET Efficiency of an Antenna Material Containing Natural Dyes and Zeolite L

“…While data needed to create absorption and emission spectra were obtained with the help of Gaussian software, spectral figures and computations of fluorescence quantum yields and spectral overlaps were attained with the help of a|e software . Geometry optimizations, ground-state energies, and absorption spectra of monomers in methanol were computed in our last work …”

“…38 Geometry optimizations, ground-state energies, and absorption spectra of monomers in methanol were computed in our last work. 39 …”

“…38 Geometry optimizations, ground-state energies, and absorption spectra of monomers in methanol were computed in our last work. 39 Geometry Optimizations and Calculations of Ground-State Energies of Isolated Dimers. First, monomers adopting a horizontal and parallel position with respect to each other were accommodated in four identical isolated dimers with the help of Argus Lab Software, and then, monomers were separated arbitrarily at end-to-end intermolecular (IM) distances of 10, 14, 17, and 21 Å to find the isolated dimer with the lowest interaction energy.…”

Assessing the Tamm-Dancoff Approximation, singlet-singlet, and singlet-triplet excitations with the latest long-range corrected double-hybrid density functionals

“…Benchmark studies of both new and existing densityfunctional approximations (DFAs) for excited-state problems constitute an essential contribution to both developers and users alike. They do not only provide the first group with important insights but they allow the second to safely pick DFAs that enable an accurate and reliable description of electronic excited states in applications such as photovoltaics, singlet-fission materials, photosynthesis, photocatalysis, or molecular photo-switches, areas of technological relevance [1][2][3][4][5][6][7][8] in which electron-transfer processes-the topic of this special issue-play a crucial role.…”