Dioxygen Reactivity of Bioinspired Copper(I) and Copper(I)/Manganese(II)-Porphyrin Systems

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Runzi Li (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Shabnam Hematian

Abstract: Transition metal-dioxygen (O2) interactions are of great importance in biological and chemical transformations involving dioxygen binding, activation, or reduction. In this work, the independent O2 reactivity of a series of bioinspired copper(I) complexes with varying ligand electronic environments, as well as the cooperative O2 reactivity of a copper(I)/manganese(II)-porphyrin assembly, were studied via variable temperature absorption (VT UV-vis-NIR), nuclear magnetic resonance (NMR), and infrared (IR) spectroscopies, along with X-ray crystallography, cyclic voltammetry (CV), and electrospray ionization mass spectrometry (ESI-MS). Our spectroscopic studies confirmed that the copper(I) complexes reversibly react with O2 to form the corresponding 1:1 copper-O2 (i.e., end-on superoxo) intermediates which can further react reversibly with second equivalents of copper(I) complexes to form the related dinuclear 2:1 copper-O2 (i.e., trans-peroxo) adducts. Small but significant variations in the Cu/O2 adducts’ spectroscopic features suggest that electronic variation in the copper chelates directly affects the electronic properties of the copper-O2 cores. Furthermore, the bioinspired copper(I) complex [(tmpa)Cu(I)(MeCN)]+ (TMPA: tris[(2-pyridyl)methyl]amine) was observed to “trigger” the O2 reactivity of a manganese(II) porphyrin which displays no independent O2 chemistry at ambient conditions: In the presence of one or two equivalents of the O2-active copper center, the O2-inert manganese center was “triggered” to cooperatively activate O2 and perform one or two electron transfers, generating the first examples of such Mn(III)/Cu(II)/O2 or Mn(IV)/Cu(II)/O2 species, respectively. The observed cooperative O2 chemistry was not possible for either metal center independently.

Additional Information

Honors Project
Language: English
Date: 2022
chemistry, inorganic chemistry, bioinorganic chemistry, dioxygen, copper, manganese, porphyrin, spectroscopy, variable-temperature absorption spectroscopy, nuclear magnetic resonance spectroscopy, superoxide, peroxide, fluorine

Email this document to