Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted 13 C Labeling and ENDOR Spectroscopy
- Award ID(s):
- 1908587
- PAR ID:
- 10275415
- Date Published:
- Journal Name:
- Journal of the American Chemical Society
- Volume:
- 143
- Issue:
- 24
- ISSN:
- 0002-7863
- Page Range / eLocation ID:
- 9183 to 9190
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract CTEA (N,N‐bis[2‐(carboxylmethyl)thioethyl]amine) is a mixed donor ligand that has been incorporated into multiple fluorescent sensors such as NiSensor‐1 that was reported to be selective for Ni2+. Other metal ions such as Zn2+do not produce an emission response in aqueous solution. To investigate the coordination chemistry and selectivity of this receptor, we prepared NiCast, a photocage containing the CTEA receptor. Cast photocages undergo a photoreaction that decreases electron density on a metal‐bound aniline nitrogen atom, which shifts the binding equilibrium toward unbound metal ion. The unique selectivity of CTEA was examined by measuring the binding affinity of NiCast and the CTEA receptor for Ni2+, Zn2+, Cd2+and Cu2+under different conditions. In aqueous solution, Ni2+binds more strongly to the aniline nitrogen atom than Cd2+; however, in CH3CN, the change in affinity virtually disappears. The crystal structure of [Cu(CTEA)], which exhibits a Jahn–Teller–distorted square pyramidal structure, was also analyzed to gain more insight into the underlying coordination chemistry. These studies suggest that the fluorescence selectivity of NiSensor‐1 in aqueous solution is due to a stronger interaction between the aniline nitrogen atom and Ni2+compared to other divalent metal ions except Cu2+.more » « less
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