Spectroscopic and theoretical study of the electronic structure of curcumin and related fragment molecules

V. Galasso, B. Kovač, A. Modelli, M. F. Ottaviani, Fabio Pichierri

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

The low volatility and thermal instability made the photoelectron (PE), electron transmission (ET), and dissociative electron attachment (DEA) spectroscopy measurements on curcumin (a potent chemopreventive agent) unsuccessful. The filled and empty electronic structure of curcumin was therefore investigated by exploiting the PES, ETS, and DEAS results for representative fragment molecules and suitable quantum-mechanical calculations. On this basis, a reliable pattern of the vertical ionization energies and electron attachment energies of curcumin was proposed. The π frontier molecular orbitals (MOs) are characterized by sizable interaction between the two phenol rings transmitted through the dicarbonyl chain and associated with a remarkably low ionization energy and a negative electron attachment energy (i.e., a largely positive electron affinity), diagnostic of a stable anion state not observable in ETS. The lowest energy electronic transitions of half-curcumin and curcumin and their color change by alkalization were interpreted with time-dependent density functional theory (DFT) calculations. For curcumin, it is shown that loss of a phenolic proton occurs in alkaline ethanolic solution.

Original languageEnglish
Pages (from-to)2331-2338
Number of pages8
JournalJournal of Physical Chemistry A
Volume112
Issue number11
DOIs
Publication statusPublished - 2008 Mar 20

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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