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| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Lekka, C. E. | en |
| dc.contributor.author | Ren, J. | en |
| dc.contributor.author | Meng, S. | en |
| dc.contributor.author | Kaxiras, E. | en |
| dc.date.accessioned | 2015-11-24T17:38:42Z | - |
| dc.date.available | 2015-11-24T17:38:42Z | - |
| dc.identifier.issn | 1520-6106 | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/14533 | - |
| dc.rights | Default Licence | - |
| dc.subject | electrospray mass-spectrometry | en |
| dc.subject | antioxidant properties | en |
| dc.subject | molecular-structure | en |
| dc.subject | metal-ions | en |
| dc.subject | iron | en |
| dc.subject | quercetin | en |
| dc.subject | systems | en |
| dc.subject | pseudopotentials | en |
| dc.subject | mechanisms | en |
| dc.subject | chelation | en |
| dc.title | Structural, Electronic, and Optical Properties of Representative Cu-Flavonoid Complexes | en |
| heal.type | journalArticle | - |
| heal.type.en | Journal article | en |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.identifier.primary | Doi 10.1021/Jp807948z | - |
| heal.identifier.secondary | <Go to ISI>://000265687500036 | - |
| heal.language | en | - |
| heal.access | campus | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών | el |
| heal.publicationDate | 2009 | - |
| heal.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. | en |
| heal.publisher | American Chemical Society | en |
| heal.journalName | Journal of Physical Chemistry B | en |
| heal.journalType | peer reviewed | - |
| heal.fullTextAvailability | TRUE | - |
| Appears in Collections: | Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά) | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| Lekka-2001-Structural, Electronic, and.pdf | 2.54 MB | Adobe PDF | View/Open Request a copy |
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