Computational Studies for Crystal Structures of Helicate Lanthanide Complexes Based on X-ray Analyses

Abstract

Abstract Computational approaches to elucidate the phase transitions in lanthanide complexes will support understanding their electronic structure changes by weak stimuli such as gas adsorptions. There are no examples as molecular models of Ln complexes for defining parameters, due to various molecular shapes with unexpected coordination numbers resulting in different packings with different Ln ions. Here, we succeeded in determining molecular force field parameters (van der Waals; vdW for Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm; and torsion parameters of the ligand) to apply the structural optimization of a series of Ln complexes taking uniform helicate for ten Ln ions with the same ligand, L, which reported previously as LnL. SmL, ErL, and TmL were newly synthesized for this calculation and the structure and luminescence properties experimentally determined. The coordination distances surrounding Ln are along the lanthanoid contraction. It is the first case to clarify the lanthanoid contraction in a 10-coordination system of a series of Ln ions. The applied optimized structures with these parameters for Eu well exhibit correspondence to observed results for four analogous of EuL. This work will strongly push development of luminescent Ln complexes with soft-crystalline behaviour.