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Spontaneous Reduction of Mononuclear High‐Spin Iron(III) Complexes to Mononuclear Low‐Spin Iron(II) Complexes in Aqueous Media and Nuclease Activity via Self‐Activation
Author(s) -
Ghosh Kaushik,
Tyagi Nidhi,
Kumar Dhara Ashish,
Singh Udai P.
Publication year - 2015
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201402954
Subject(s) - chemistry , density functional theory , aqueous solution , nuclease , chelation , crystallography , redox , electrochemistry , spin states , fluorescence , inorganic chemistry , computational chemistry , organic chemistry , enzyme , electrode , physics , quantum mechanics
Mononuclear high‐spin [Fe III (Pyimpy)Cl 3 ]⋅2 CH 2 Cl 2 ( 1 ⋅2 CH 2 Cl 2 ) and [Fe III (Me‐Pyimpy)Cl 3 ] ( 2 ), as well as low‐spin Fe II (Pyimpy) 2 ](ClO 4 ) 2 ( 3 ) and [Fe II (Me‐Pyimpy) 2 ](ClO 4 ) 2 ( 4 ) complexes of tridentate ligands Pyimpy and Me‐Pyimpy have been synthesized and characterized by analytical techniques, spectral, and X‐ray structural analyses. We observed an important type of conversion and associated spontaneous reduction of mono‐chelated high‐spin Fe III ( 1 ⋅2 CH 2 Cl 2 and 2 ) complexes to low‐spin bis‐chelated Fe II complexes 3 and 4 , respectively. This process has been explored in detail by UV/Vis, fluorescence, and 1 H NMR spectroscopic measurements. The high positive potentials observed in electrochemical studies suggested a better stabilization of Fe II centers in 3 and 4 . Theoretical studies by density functional theory (DFT) calculations supported an increased stabilization for 3 in polar solvents. Self‐activated nuclease activity of complexes 1 ⋅2CH 2 Cl 2 and 2 during their spontaneous reduction was examined for the first time and the mechanism of nuclease activity was investigated.