Lanthanide-containing complexes are important compounds for sophisticated nuclear-fuel processing and medical imaging. Moreover, they often have interesting symmetric crystal structures and associated dynamics that render unique properties for practical applications. The seven-coordinate lanthanide complex Ho(III) aqua-tris(dibenzoylmethane) or Ho-(DBM)3·H2O was first reported in the late 1960s.
It has a three-fold symmetric structure with holmium (Ho) at the center of three propeller-shaped dibenzoylmethane (DBM) ligands and a water (H2O) molecule hydrogen-bonded to the ligands. Unfortunately, the understanding of the molecular dynamics (MD) of such lanthanide complexes has been limited due to challenges in describing their interactions using the classical MD framework.
This motivated a team of researchers from the Graduate School of Engineering at Chiba University, led by Associate Professor Takahiro Ohkubo, to elucidate the structure and dynamics of the Ho-(DBM)3·H2O complex. This study was published in Inorganic Chemistry and is co-authored by Associate Professor Hyuma Masu, Professor Keiki Kishikawa, and Associate Professor Michinari Kohri.
“Hydrogen bonds between the water molecule and the ligands surrounding Ho are considered to play an important role in the formation of the symmetrical structure of the novel lanthanide complex. After synthesizing its single crystal and bulk samples, the next logical step was to model this complex to test this hypothesis and understand its structure and dynamics,” explains Dr. Ohkubo.
Considering the shortcomings of existing general force-fields (a functional form used to estimate forces between atoms) in satisfactorily describing the interactions of lanthanide metals such as Ho, the researchers developed new force-field parameters for conducting classical MD simulations of the Ho-(DBM)3·H2O complex. They performed structural optimization and MD steps using ab initio calculations based on the plane-wave pseudopotential method to make training data for force-fields’ development.
2023-08-23 13:24:02
Article from phys.org