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Photoinitiated Dioxygenase‐Type Reactivity of Open‐Shell 3d Divalent Metal Flavonolato Complexes
Author(s) -
Grubel Katarzyna,
Marts Amy R.,
Greer Samuel M.,
Tierney David L.,
Allpress Caleb J.,
Anderson Stacey N.,
Laughlin Brynna J.,
Smith Rhett C.,
Arif Atta M.,
Berreau Lisa M.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200212
Subject(s) - chemistry , reactivity (psychology) , electron paramagnetic resonance , dioxygenase , isomerization , catalysis , divalent , metal , stoichiometry , photochemistry , nuclear magnetic resonance spectroscopy , inorganic chemistry , stereochemistry , organic chemistry , nuclear magnetic resonance , medicine , physics , alternative medicine , pathology , enzyme
Irradiation of 3‐hydroxyflavonolato (3‐Hfl) complexes of Mn II , Co II , Ni II and Cu II ( 1 – 4 ) at 300 nm under aerobic conditions results in dioxygenase‐type reactivity and the formation of the corresponding divalent metal O ‐benzoylsalicylato ( O ‐bs) complexes 8 – 11 and CO. The latter were characterized by using multiple methods, including elemental analysis, X‐ray crystallography, NMR and/or EPR spectroscopy, mass spectrometry and IR spectroscopy. Compounds 1 – 4 serve as catalysts for the photoinduced reactivity of 3‐hydroxyflavonol (3‐HflH) to produce O ‐benzoylsalicylic acid as the major product. Spectroscopic studies (UV/Vis and 1 H NMR) show that each O ‐benzoylsalicylato complex 8 – 11 reacts with one equiv. of 3‐hydroxyflavonol to regenerate 1 – 4 and enable turnover reactivity. Unlike what is observed for free 3‐HflH, photoinduced reactions involving 1 – 4 and excess flavonol show only minor amounts of flavonol isomerization reactivity. These results indicate that the presence of a metal ion, whether under stoichiometric or catalytic conditions, facilitates the photoinduced degradation of 3‐HflH to produce a carboxylic acid and CO as products.