Understanding the Binding of Nickel(II) Bromide to a Zirconium Metal-Organic Cage for Heterogeneous Catalysis

Authors

• Luci Green, University of South Carolina - ColumbiaFollow

Abstract

Heterogeneous catalysts offer inherent advantages in improving the sustainability of industrial chemical processes. Their high ease of separation and recyclability has the potential to reduce the cost, waste, and energy consumption of processes that currently rely on homogeneous catalysts. Metal–organic cages (MOCs) are an attractive material for heterogeneous catalysis due to their discrete and highly tunable structures, which can be functionalized by binding these complexes with catalytically active metals. The specific objective of this study is to provide preliminary insight into the binding of nickel(II) bromide (NiBr₂) to zirconium MOCs, which was done by studying the binding of NiBr₂ to 2,2’- bipyridyl, an analog of the organic linkers of the MOC. UV–vis spectroscopy titration experiments in dimethylformamide (DMF) indicate the formation of a complex equilibria between mono-, bis-, and tris-bipyridine nickel complexes. By contrast, when nickel(II) bromide was introduced to the MOC, a distinct 1:1 binding stoichiometry was observed, suggesting that the MOC provides a well-defined coordination environment. Additional findings revealed promising coordination behavior in another ligand analog, dimethyl [2,2'-bipyridine]-5,5'-dicarboxylate. These findings suggest that bipyridine-functionalized zirconium MOCs can provide well-defined, single-site metal coordination environments and show promise as high-performing heterogeneous catalysts, but further research is needed to determine how the poor coordination behavior of free ligands influences how they ultimately bind metals when incorporated into the MOC structure. Future work will additionally explore the binding of other catalytically active metals, such as rhodium, manganese, and iron, to cages and their analogs to optimize these systems for industrially relevant chemical processes.

Recommended Citation

Green, Luci (2026) "Understanding the Binding of Nickel(II) Bromide to a Zirconium Metal-Organic Cage for Heterogeneous Catalysis," Caroliniana Undergraduate Research Journal: Vol. 1: Iss. 1, Article 3.
Available at: https://scholarcommons.sc.edu/usc-curj/vol1/iss1/3