title: Solid-state 13C NMR investigations of cyclophanes: [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane.
abstract: Solid-state NMR (ssNMR) and ab initio quantum mechanical calculations are used in order to understand and to better characterize the molecular conformation and properties of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane. Both molecules are cyclophanes, consisting of an aromatic ring assembly and a cyclic aliphatic chain connected to both ends of the aromatic portion. The aliphatic chain causes curvature in the six-membered aromatic ring structures. This led us to examine how the ring strain due to curvature affects the chemical shifts. Using X-ray structures of both [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane as our starting model, we calculate the chemical shielding tensors and compare these data with those collected from the (13)C ssNMR FIREMAT experiment. We define curvature of [2.2]paracyclophane and 1,8-dioxa[8](2,7)pyrenophane using the π-orbital axis vector (POAV) pyramidalization angle (θ(p)).
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Merrill D
authors.initials: MD
authors.lastname: Halling
authors.forename: Kiran Sagar
authors.initials: KS
authors.lastname: Unikela
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Bodwell
authors.forename: David M
authors.initials: DM
authors.lastname: Grant
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Pugmire