The NAD+/NADH Redox Couple—Insights from the Perspective of Electrochemical Energy Transformation and Biomimetic Chemistry

Abstract

The constructions of various photochemical systems and catalysts have become a common theme in the realm of metal-catalyzed energy transformation. The biologically important redox couple β-nicotinamide adenine dinucleotide (NAD+)/1,4,β-dihydronicotinamide adenine dinucleotide (NADH) provides a reversible prototype system for the conversion of electrical to chemical energy via the reversible formation of a C–H bond centered on the nicotinamide ring representing an efficient system for numerous biological hydrogen-transfer reactions. In this short review, the first part emphasizes the need to construct operational system for the catalytic transformation of energy from viable sources due to the globally increasing demand in energy consumption. This is followed by a discussion on the redox chemistry of the NAD+/NADH reversible redox process centered on the nicotinamide ring as a representative chemical system enabling the efficient transformation of energy. Next, pioneering examples of NAD+/NADH mimics providing model systems that can perform non-enzymatic reactions based on the hydrogen (hydride) transfer ability of the model compounds are outlined. And lastly, several examples of ruthenium polypyridyl complexes having NAD+/NADH analogous ligands exhibiting excellent photo- and electrochemical properties similar to the NAD+/NADH redox couple are given. This is to demonstrate the importance of biomimetic chemistry in realizing novel strategies in the development of catalytic systems that can provide solutions in the alleviation or eradication of the world’s energy problems.