Neodymium oxygen chemistry advances with Rice molecular basket
Rice chemists used a molecular scaffold to make neodymium bind oxygen, opening a route to reactive rare-earth oxo compounds.
By Priya Raghavan · Science Reporter
3 min read
Rice University chemists have reported a new advance in neodymium oxygen chemistry, using a custom molecular scaffold to make the rare-earth metal interact with dioxygen in a way researchers had considered unlikely. The work matters because it points toward highly reactive lanthanide oxo compounds that could give chemists alternatives to iron-based molecules used in biology-related reactions and chemical manufacturing.
The study, published in the Journal of the American Chemical Society, was led by Hong-Lei Xu, Alejandro Fuentes Beltrán and Raúl Hernández Sánchez. Rice University said the team used a ligand platform that Hernández Sánchez describes as a molecular “basket” to hold and position metal atoms so specific bonds could form.
What did Rice chemists discover about neodymium and oxygen?
The researchers found conditions under which dioxygen, a molecule made of two oxygen atoms, could form pi interactions with neodymium, a lanthanide metal. According to Rice University, that interaction allowed the team to make lanthanide oxo compounds, a class of highly reactive molecules.
Pi interactions are important in many biological materials, including proteins, but f-block metals such as lanthanides had not been expected to engage small molecules like oxygen in that way. Lanthanides sit in the upper row of the f-block near the bottom of the periodic table; actinides occupy the row below them.
Hernández Sánchez, an assistant professor of chemistry at Rice, pursued the question because iron and oxygen already play central roles in living systems. Hemoglobin uses iron to bind dioxygen and move oxygen through the bloodstream, while reactive iron oxo compounds participate in other biological chemistry, including liver enzyme reactions that help process drugs.
How the molecular basket worked
Rice University said each ligand “basket” was designed to hold one f-block metal atom. The researchers placed two baskets facing each other and arranged six atoms between them, including a dioxygen molecule, to connect two neodymium atoms.
That setup created what the team described as an octacoordinate ligand environment, giving the scientists control over the metals’ positions. Xu, a postdoctoral researcher at Rice and first author of the study, said the team tested how the lanthanide in the basket reacted with small molecule substrates until it found the conditions that bound dioxygen in the unusual arrangement.
The result was not limited to holding oxygen in place. Rice University said the system also enabled cleavage of the bond between the two oxygen atoms, producing a lanthanide oxo molecule.
Why lanthanide oxo compounds could matter
The immediate finding gives chemists a new way to study oxygen activation by rare-earth metals. Rice University said researchers can now test whether lanthanide oxos can substitute for iron oxos in synthetic chemistry or perform reactions that iron-based compounds cannot.
The published experiment focused on neodymium, but Hernández Sánchez and colleagues believe the same ligand scaffold may work with most lanthanides and probably actinides as well. Hernández Sánchez said the ability to bind dioxygen to f-block metals and split the oxygen-oxygen bond could reveal reactive lanthanide oxos and support formation of high value-added chemicals.
Rice University said the research received startup funding from the university, support from the Robert A. Welch Foundation and Welch Foundation Grant C-2142-20230405.
This story draws on original reporting from ScienceDaily.