Computational Chemistry Investigation of Spin Traps Using Hybrid Solvation Models

The cyclic nitrone 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and the lesser known linear phenyl-N-tert-butylnitrone (PBN) and its phosphorylated analogs have been used as spin traps for the investigation of free radicals in biol. systems. Theor. work on these mols. suggests that there are significant differences in their properties between biol. systems and isolated mols. in the gas phase, most likely resulting from intra and intermol. hydrogen bonding. Most dielec. solvation models such as the polarized continuum model and COSMO are incapable of direct detn. of solvent-spin trap chem. interactions. To examine this, hybrid models incorporating COSMO for long range effects and discrete solvent mols. for short range effects, at the DFT/B3LYP/6-31G* level of theory, have been used to study the stabilization and alteration of the spin trap mols. properties in protic and aprotic polar solvents