The power of molecular chemistry in nanoscale materials research: from quantum physics properties to water oxidation catalysis

Molecular chemistry brings many powerful advantages to the study of nanoscale materials of various kinds, and this area of ‘molecular nanoscience’ is therefore a rapidly growing field. The advantages include monodisperse (single-size) products and a monolayer shell of organic ligands that imparts solubility and crystallinity, allowing structural characterization of molecular crystals to atomic resolution by X-ray crystallography. The ligands can usually also be modified as desired, allowing tuning of redox properties and atom/isotope labelling (²H, ¹⁹F, etc.) for studies in the solid state and solution, such as NMR spectroscopy. In the molecular nanomagnetism arena, these advantages have been absolutely crucial in the study of single-molecule magnets (SMMs), molecules that function as individual ultra-small nanomagnets. They have greatly assisted the synthesis and study of numerous SMMs, leading to discovery of new quantum physics phenomena important to new 21^st century technologies, such as exchange-biased quantum tunneling of the magnetization vector and quantum superposition states. Giant (~4 nm) SMMs have also bridged the gap between the ‘top-down’ world of traditional magnetic nanoparticles and the ‘bottom-up’ world of molecular nanomagnets. Recently we have developed controlled ways to form supramolecular [Mn₃]_n oligomers of 2 or more linked Mn₃ SMMs to study the resulting quantum properties, introduced by the weak inter-SMM exchange coupling, in more detail, including in solution for the first time. Some of our larger magnetic molecules, such as [Mn₁₂O₁₂(O₂CR)₁₆(H₂O)₄] and others, can be described as a small piece of metal oxide within an organic shell, and recent work has established that they can also function as homogeneous electrocatalysts for water oxidation to O₂ gas with low overpotentials. A selection of these materials and studies will be described.