Related Experiment Video
Updated: Aug 14, 2026
08:05
Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Bioinspired Nitrite Reduction to Ammonia by Molecular Nickel Polypyridine-Quinoline Complex
Sabarni Paul1, Biplab Gope2, Aniruddha Paik1
1Department of Chemistry, University of North Bengal, Darjeeling734013, India.
Journal of the American Chemical Society
|August 12, 2026
Summary
A nickel complex mimics natural enzymes by reducing nitrite to ammonia, involving key intermediates. Ligand design controls product selectivity, offering insights into catalytic nitrite reduction pathways.
Area of Science:
- Inorganic Chemistry
- Bioinorganic Chemistry
- Catalysis
Background:
- The enzyme cytochrome-c-nitrite reductase (CcNiR) naturally converts nitrite to ammonia through several intermediates.
- Understanding biomimetic pathways for nitrite reduction is crucial for developing new catalysts.
Purpose of the Study:
- To synthesize and characterize a nickel complex that mimics CcNiR's nitrite reduction to ammonia.
- To investigate the intermediates involved in the catalytic cycle.
- To explore ligand effects on product selectivity.
Main Methods:
- Electrochemical and stoichiometric chemical reduction of a nickel nitrito complex ([NiII(2PyN2Q)(k-ONO)](BF4)]).
- Characterization using NMR (1H, 31P{1H}, 15N), EPR, UV-vis, and FT-IR spectroscopy.
- 15N isotopic labeling studies.
- Computational chemistry for reaction profiling.
Main Results:
- The nickel complex successfully reduced nitrite to ammonia, involving nitric oxide, nitroxyl, hydroxylamine, and ammonia.
- High Faradaic efficiencies were achieved for electrocatalytic nitrite reduction in various media.
- A related nickel nitro complex yielded hydroxylamine exclusively, demonstrating ligand-controlled selectivity.
- Computational studies elucidated the reaction mechanism and energy profile.
Conclusions:
- The designed nickel complex effectively mimics enzymatic nitrite reduction to ammonia.
- The quinoline moiety in the ligand is key for facilitating stepwise reduction via proton-coupled electron transfer.
- Ligand structure dictates product selectivity in nickel-catalyzed nitrite reduction.
More Related Videos
Related Concept Videos
01:29Preparation of Amines: Reduction of Oximes and Nitro Compounds
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
01:22Inorganic Nitrogen Assimilation
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme nitrate reductase...
00:55Nitriles to Amines: LiAlH4 Reduction
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
01:371° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
01:13Preparation of Amines: Reduction of Amides and Nitriles
Nitriles can be reduced to primary amines using reducing agents like lithium aluminum hydride or catalytic hydrogenation. The reduction introduces an amino group with an extra carbon in the skeleton. Nitriles are formed from the reaction between alkyl halides and sodium cyanide through the SN2 mechanism. Primary alkyl halides are the preferred substrates to prepare nitriles.
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
01:20Electrophilic Aromatic Substitution: Nitration of Benzene
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.