Computational Approaches to the Study of Some Lanthanide (III) - Polyazamacrocyclic Chelates for Magnetic Resonance Imaging

摘要

A set of parameters consistent with the CHARMM force field has been determined for molecular dynamics simulations of several DOTA- and DOTP-Ln(III) chelates. Bonding and van der Waals parameters were derived from the available experimental data and analogy to similar ones in the existing force field. Net atomic charges were derived from ab initio calculations at the Hartree-Fock level to reproduce molecular electrostatic potentials (ESPs), with an effective core potential (ECP) basis set for the metal ion and the 6-31G~* basis set for the ligand atoms. The charges are consistent with the TIP3P water mode. Preliminary molecular dynamics simulations of the lanthanide chelates in aqueous solution were performed using the Nose-Hoover thermostat at 300 K. The new parameters correctly predicted the molecular structures and stability of the chelates major and minor isomers.