Computational Study of Lanthanum-Aspartate Complexes: An ESI-MS-Assisted DFT Approach

The separation of rare-earth elements (REEs) remains challenging due to their similar chemical properties. Lanmodulin (LanM), a protein with high selectivity for lanthanides, has emerged as a promising green alternative for REE separation. This study investigated the stability of lanthanum–aspartate (La–ASP) complexes using density functional theory (DFT) based on electrospray ionization mass spectrometry (ESI-MS) data. The most intense mass spectral peak (m/z 279) was used as the precursor for modeling reaction products. DFT calculations revealed that nitrate-containing complexes are significantly more stable (ΔG = -280.11 to -305.71 kcal mol⁻¹) than nitrate-free species. The most stable complex (m/z 466) exhibited a coordination number of 7, indicating enhanced structural stability. These findings improve the understanding of La–ASP interactions and provide a foundation for future computational studies employing higher-level methods with relativistic corrections.