title: Nuclear Magnetic Shieldings of Stacked Aromatic and Antiaromatic Molecules.
abstract: Nuclear magnetic shieldings have been calculated at the density functional theory (DFT) level for stacks of benzene, hexadehydro[12]annulene, dodecadehydro[18]annulene, and hexabenzocoronene. The magnetic shieldings due to the ring currents in the adjacent molecules have been estimated by calculating nucleus independent molecular shieldings for the monomer in the atomic positions of neighbor molecules. The calculations show that the independent shielding model works reasonably well for the1H NMR shieldings of benzene and hexadehydro[12]annulene, whereas for the larger molecules and for the13C NMR shieldings the interaction between the molecules leads to shielding effects that are at least of the same size as the ring current contributions from the adjacent molecules. A better agreement is obtained when the nearest neighbors are also considered at full quantum mechanical (QM) level. The calculations suggest that the nearest solvent molecules must be included in the quantum mechanical system, at least when estimating solvent shifts at the molecular mechanics (MM) level. Current density calculations show that the stacking does not significantly affect the ring current strengths of the individual molecules, whereas the shape of the ring current for a single molecule differs from that of the stacked molecules.
authors.affiliation: Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtanens plats 1, FIN-00014 Helsinki, Finland.
authors.forename: Dage
authors.identifier: http://orcid.org/0000-0002-2367-9277
authors.initials: D
authors.lastname: Sundholm
authors.affiliation: Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtanens plats 1, FIN-00014 Helsinki, Finland.
authors.forename: Markus
authors.initials: M
authors.lastname: Rauhalahti
authors.affiliation: Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtanens plats 1, FIN-00014 Helsinki, Finland.
authors.forename: Nergiz
authors.initials: N
authors.lastname: Özcan
authors.affiliation: Departamento de Ciencias del Ambiente, Universidad de Santiago de Chile (USACH) , Av. Libertador Bernardo O'Higgins 3363, 9170022 Estación Central, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Mera-Adasme
authors.affiliation: Department of Chemistry, University of Munich (LMU) , München D-81377, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Kussmann
authors.affiliation: Department of Chemistry, University of Munich (LMU) , München D-81377, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Luenser
authors.affiliation: Department of Chemistry, University of Munich (LMU) , München D-81377, Germany.
authors.forename: Christian
authors.identifier: http://orcid.org/0000-0002-4189-6558
authors.initials: C
authors.lastname: Ochsenfeld