title: Interplay of stereo-electronic, environmental, and dynamical effects in determining the EPR parameters of aromatic spin-probes: INDCO as a test case.
abstract: An integrated computational strategy for the evaluation of reliable structures and magnetic properties of spin probes and spin labels has been extended to aromatic species. From an electronic point of view, delocalization of the unpaired electron density over aromatic moieties reduces significantly the computed nitrogen isotropic hyperfine coupling constant (A(N)) with respect to values characteristic of aliphatic nitroxides. Solvent effects in not too high polarity media are quite small, but not negligible. At this stage computed A(N) are lower than their experimental counterparts by more than 1 G. Inclusion of vibrational averaging effects by molecular dynamics simulations with a new reliable force field restores full agreement with experiment pointing out the limits of static approaches irrespective of the sophistication of the electronic quantum mechanical method. The generality and computational effectiveness of the proposed integrated approach paves the route toward a reliable analysis of the interplay of stereo-electronic, environmental, and dynamical effects in tuning the properties of large flexible magnetic systems of biological and technological interest.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università di Salerno, via Ponte don Melillo, 84084, Fisciano (Sa), Italy. cimino@unisa.it
authors.forename: Paola
authors.initials: P
authors.lastname: Cimino
authors.forename: Alfonso
authors.initials: A
authors.lastname: Pedone
authors.forename: Emiliano
authors.initials: E
authors.lastname: Stendardo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013113:Spin Labels; D013237:Stereoisomerism
chemical_list: C121894:1,2-dihydro-2-methyl-2-phenyl-3H-indol-3-one-1-oxyl; D003497:Cyclic N-Oxides; D012997:Solvents; D013113:Spin Labels