Vibrational signatures of curcumin's chelation in copper(II) complexes: An appraisal by IRMPD spectroscopy.
J Chem Phys
; 150(16): 165101, 2019 Apr 28.
Article
en En
| MEDLINE
| ID: mdl-31042893
Curcumin (Cur) is a natural polyphenol with a wide spectrum of biological activities and appealing therapeutic potential. Herein, it has been delivered by electrospray ionization as gaseous protonated species, [Cur + H]+, and as a Cu(ii) complex, [Cu(Cur - H)]+, a promising antioxidant and radical scavenger. The gas phase structures were assayed by infrared multiple photon dissociation (IRMPD) spectroscopy in both the fingerprint (800-2000 cm-1) and hydrogen stretching (3100-3750 cm-1) ranges. Comparison between the experimental features and linear IR spectra of the lowest energy structures computed at the B3LYP/6-311+G(d,p) level reveals that bare [Cu(Cur - H)]+ exists in a fully planar and symmetric arrangement, where the metal interacts with the two oxygens of the syn-enolate functionality of deprotonated Cur and both OCH3 groups are engaged in H-bonding with the ortho OH. The effect of protonation on the energetic and geometric determinants of Cur has been explored as well, revealing that bare [Cur + H]+ may exist as a mixture of two close-lying isomers associated with the most stable binding motifs. The additional proton is bound to either the diketo or the keto-enol configuration of Cur, in a bent or nearly planar arrangement, respectively.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
J Chem Phys
Año:
2019
Tipo del documento:
Article
País de afiliación:
Italia
Pais de publicación:
Estados Unidos