dc.contributor.author | Lekka, Ch. E. | |
dc.contributor.author | Ren, Jun | |
dc.contributor.author | Meng, Sheng | |
dc.contributor.author | Kaxiras, Efthimios | |
dc.date.accessioned | 2019-09-20T17:27:43Z | |
dc.date.issued | 2009 | |
dc.identifier.citation | Lekka, Ch. E., Jun Ren, Sheng Meng, and Efthimios Kaxiras. 2009. “Structural, Electronic, and Optical Properties of Representative Cu−Flavonoid Complexes.” The Journal of Physical Chemistry B 113 (18): 6478–83. https://doi.org/10.1021/jp807948z. | |
dc.identifier.issn | 1089-5647 | |
dc.identifier.issn | 1520-5207 | |
dc.identifier.issn | 1520-6106 | |
dc.identifier.uri | http://nrs.harvard.edu/urn-3:HUL.InstRepos:41384030 | * |
dc.description.abstract | We present density functional theory (DFT) results on the structural, electronic, and optical properties of Cu-flavonoid complexes for molar ratios 1:1, 1:2, and 1:3. We find that the preferred chelating site is close to the 4-oxo group and in particular the 3-4 site followed by the 3'-4' dihydroxy group in ring B. For the Cu-quercetin complexes, the large bathochromic shift of the first absorbance band upon complexation, which is in good agreement with experimental UV-vis spectra, results from the reduction of the electronic. energy gap. The HOMO states for these complexes are characterized by pi-bonding between the Cu d orbitals and the C, 0 p orbitals except for the case of 1:1. complex (spin minority), which corresponds to sigma-type bonds. The LUMO states are attributed to the contribution of Cu pz orbitals. Consequently, the main features of the first optical absorption maxima are essentially due to pi -> pi* transitions, while the 1:1 complex exhibits also sigma -> pi* transitions. Our optical absorption calculations based on time-dependent DFT demonstrate that the 1: 1 complex is responsible for the spectroscopic features at pH 5.5, whereas the 1:2 complex is mainly the one responsible for the characteristic spectra at pH 7.4. These theoretical predictions explain in detail the behavior of the optical absorption for the Cu-flavonoid complexes observed in experiments and are thus useful in elucidating the complexation mechanism and antioxidant activity of flavonoids. | |
dc.language.iso | en_US | |
dc.publisher | American Chemical Society | |
dash.license | META_ONLY | |
dc.title | Structural, Electronic, and Optical Properties of Representative Cu−Flavonoid Complexes | |
dc.type | Journal Article | |
dc.description.version | Version of Record | |
dc.relation.journal | The Journal of Physical Chemistry Part B - Condensed Matter, Materials, Surfaces, Interfaces and Biophysical | |
dash.depositing.author | Kaxiras, Efthimios::2866c62f1d7e85db187eaf76c6f5ce68::600 | |
dc.date.available | 2019-09-20T17:27:43Z | |
dash.workflow.comments | 1Science Serial ID 112179 | |
dc.identifier.doi | 10.1021/jp807948z | |
dash.source.volume | 113;18 | |
dash.source.page | 6478-6483 | |