Dinitrogen molecule (N
2) is the most abundant natural gas and also the ultimate source of nitrogen for nitrogenated industrial and natural compounds. So far, the fully hydrogenated product, ammonia (NH
3), is the most common product of N
2 fixation.
1 However, NH
3, the regular end-product of N
2 fixation, is a bulk chemical with low added-value. The conversion of NH
3 to nitrogenous compounds with high added-value and complicated structure still requires further tedious chemical synthesis with the use of precious metal catalysts.
2 In our study, an upgraded N
2 fixation system was firstly designed and constructed based on a bioelectrocatalytic N
2 reduction architecture.
3 The NH
3 generated via N
2 reduction catalyzed by nitrogenase was
in situ utilized by
L-alanine dehydrogenase to realize the reductive amination of pyruvate and the generation of alanine. The reduced equivalent to support the N
2 reduction and reductive amination of pyruvate was regenerated by the electrochemical method. ω-TA transferred the amino group from alanine to ketone substrates and finally produced desired chiral amine intermediates.
4 On this basis, an H
2 fuel cell module was integrated into the upgraded N
2 fixation system to construct a self-powered H
2/α-keto acid fuel cell. In the new system, the upgraded N
2 fixation was powered by the oxidation of H
2 with high Faradaic efficiency and without the requirement of external electrical energy input.
5 Finally, the end-product of N
2 fixation in our study successfully went beyond NH
3 and reached high-value-added chiral amine intermediates and chiral amino acids. The produced chiral amine intermediates and chiral amino acids have wild application in pharmaceuticals production and biotechnology research.
References
(1) Foster, S. L.; Bakovic, S. I. P.; Duda, R. D.; Maheshwari, S.; Milton, R. D.; Minteer, S. D.; Janik, M. J.; Renner, J. N.; Greenlee, L. F. Catalysts for nitrogen reduction to ammonia. Nat. Catal. 2018, 1, 490.
(2) Balaraman, E.; Srimani, D.; Diskin-Posner, Y.; Milstein, D. Direct synthesis of secondary amines from alcohols and ammonia catalyzed by a ruthenium pincer complex. Catal. Lett. 2015, 145, 139-144.
(3) Milton, R. D.; Cai, R.; Abdellaoui, S.; Leech, D.; De Lacey, A. L.; Pita, M.; Minteer, S. D. Bioelectrochemical Haber-Bosch Process: An Ammonia-Producing H2/N2 Fuel Cell. Angew. Chem. Int. Ed. 2017, 56, 2680-2683.
(4) Chen, H.; Cai, R.; Patel, J.; Dong, F.; Chen, H.; Minteer, S. D. Upgraded Bioelectrocatalytic N2 Fixation: From N2 to Chiral Amine Intermediates. J. Am. Chem. Soc. 2019, 141, 4963-4971.
(5) Chen, H.; Prater, M. B.; Cai, R.; Dong, F.; Chen, H.; Minteer, S. D., Bioelectrocatalytic Conversion from N2 to Chiral Amino Acids in a H2/α-Keto Acid Enzymatic Fuel Cell. J. Am. Chem. Soc. 2020, 142 (8), 4028-4036.
