Predictive simulation of effectively emitting mesogenic binuclear lanthanide(III) complexes by DFT, molecular dynamics, and the Judd-Ofelt theory

Abstract

This article represents the results of quantum-chemical simulation of the molecular structure and luminescence characteristics of some mesogenic binuclear lanthanide(III) (Ln(III)) complexes with substituted β-diketones and several bridging ligands using a combination of simulation techniques such as DFT, molecular dynamics, semiempirical methods, the Judd-Ofelt theory, the Voronoi-Dirichlet polyhedra method, etc. The relationships between the geometric parameters, structural features of the coordination polyhedra of the complexes, and the probability of their exhibiting liquid-crystalline properties were analyzed and a ligand environment for obtaining mesogenic binuclear Ln(III) complexes was proposed.Based on the calculated values of the lowest singlet and triplet excited states of the ligands, the energy level diagrams were constructed, and the main channels of intramolecular energy transfer between excited levels of ligands and Ln(III) ions were established. The probability of interionic energy transfer was considered. The calculated theoretical values of energy transfer rates and quantum yields indicate the dominant role of the first excited singlet state of the ligands and the 5D4 level of the Tb(III) ion in the energy transfer process. The intramolecular energy transfer rates and luminescence quantum yields were successfully applied to rationalize the selection of ligand environment for the subsequent rational design and experimental preparation of mesogenic complexes with intense luminescence. Thereby this publication propose an effective tool for the construction of new functional materials for optoelectronic devices.