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Bioinorganic Chemistry and Applications
Volume 2016, Article ID 3585781, 10 pages
http://dx.doi.org/10.1155/2016/3585781
Research Article

Reversible Oxygenation of α-Amino Acid–Cobalt(II) Complexes

1Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education and Xinjiang Uyghur Autonomous Region, College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi, Xinjiang 830046, China
2College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, China

Received 27 October 2015; Revised 21 December 2015; Accepted 22 December 2015

Academic Editor: Luigi Casella

Copyright © 2016 Xincun Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We systematically investigated the reversibility, time lapse, and oxygenation-deoxygenation properties of 15 natural -amino acid–Co(II) complexes through UV-vis spectrophotometer, polarographic oxygen electrode, and DFT calculations, respectively, to explore the relationship between the coordinating structure and reversible oxygenation of -amino acid–Co(II) complexes. Results revealed that the -amino acid structure plays a key role in the reversible oxygenation properties of these complexes. The specific configuration of the -amino acid group affects the electron of Co(II) transfer to the orbit of O2; this phenomenon also favors the reversible formation and dissociation of Co–O2 bond when O2 coordinates with Co(II) complexes. Therefore, the co-coordination of amino and carboxyl groups is a determinant of Co complexes to absorb O2 reversibly. The group adjacent to the -amino acid unit evidently influences the dioxygen affinity and antioxidation ability of the complexes. The presence of amino (or imino) and hydroxy groups adjacent to the -amino acid group increases the oxygenation-deoxygenation rate and the number of reversible cycles. Our findings demonstrate a new mechanism to develop reversible oxygenation complexes and to reveal the oxygenation of oxygen carriers.