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Antioxidants play important roles in eliminating reactive oxygen species (ROS), which have been associated with various degenerative diseases, such as cancer, aging, and inflammatory diseases. Gallic acid (GA) and propyl gallate (PG) are well-known antioxidants and have been widely studied in vitro and in vivo. The biological antioxidant abilities of GA and PG are related to the electronic structure of their dehydro-radicals. In this work, we report a combined photoelectron spectroscopic and computational study of the deprotonated gallic acid anion, [GA – H]−, and deprotonated propyl gallate anion, [PG – H]−. Adiabatic electron affinities of the dehydro-gallic acid radical, [GA – H]· and of the dehydro-propyl gallate radical, [PG – H]·, are measured to be 2.90 ± 0.05 eV and 2.85 ± 0.05 eV, respectively, and compared to computational results.more » « less
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We have prepared the hydrogen sulfide trimer and tetramer anions, (H 2 S) 3 − and (H 2 S) 4 − , measured their anion photoelectron spectra, and applied high-level quantum chemical calculations to interpret the results. The sharp peaks at low electron binding energies in their photoelectron spectra and their diffuse Dyson orbitals are evidence for them both being dipole-bound anions. While the dipole moments of the neutral (H 2 S) 3 and (H 2 S) 4 clusters are small, the excess electron induces structural distortions that enhance the charge-dipolar attraction and facilitate the binding of diffuse electrons.more » « less
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The metallo-formate anions, M(CO 2 ) − , M = Ni, Pd, and Pt, were formed by electron-induced CO 2 activation. They were generated by laser vaporization and characterized by a combination of mass spectrometry, anion photoelectron spectroscopy, and theoretical calculations. While neutral transition metal atoms are normally unable to activate CO 2 , the addition of an excess electron to these systems led to the formation of chemisorbed anionic complexes. These are covalently bound, formate-like anions, in which their CO 2 moieties are significantly reduced. In addition, we also found evidence for an unexpectedly attractive interaction between neutral Pd atoms and CO 2 .more » « less
