title: Synthesis, structure and paramagnetic NMR analysis of a series of lanthanide-containing [LnTi6O3(OiPr)9(salicylate)6] cages.
abstract: The influence of paramagnetic Ln3+ions on the NMR behaviour is investigated via a series of new isostructural lanthanide-containing cages with the general formula [LnTi6O3(OiPr)9(salicylate)6] (Ln-1, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er). Compared to conventional coordination compounds containing Ln3+ions, the peripheral ligands in Ln-1 are separated from the paramagnetic lanthanide centres by oxo-Ti4+linkages, and therefore experience a weaker paramagnetic influence. As a result, all of the1H and13C NMR signals of these Ln-1 cages (except for Gd-1) are observed and can be unambiguously assigned, which provides an excellent platform for the in-depth study of the NMR behaviour of paramagnetic Ln3+ions. Further analysis of the fully assigned paramagnetic signals suggests that the pseudo-contact component dominates the1H NMR shifts, whereas both the pseudo-contact and Fermi-contact contributions affect the13C shifts, although the majority of the resonance environments are at least four bonds distant from the central Ln3+ion. Our results also show that the use of Bleaney's factors to describe the pseudo-contact shift is inadequate for this Ln-1 cage series.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK. dsw1000@cam.ac.uk and Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, 08-03, Innovis, Singapore138634, Singapore.
authors.forename: Ning
authors.identifier: http://orcid.org/0000-0003-0179-1425
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK. dsw1000@cam.ac.uk.
authors.forename: Raúl
authors.identifier: http://orcid.org/0000-0003-0699-3894
authors.initials: R
authors.lastname: García-Rodríguez
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK. dsw1000@cam.ac.uk and School of Chemistry, University of Manchester, Oxford Road, M13 9PL, UK.
authors.forename: Peter D
authors.identifier: http://orcid.org/0000-0002-1362-8003
authors.initials: PD
authors.lastname: Matthews
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, 08-03, Innovis, Singapore138634, Singapore.
authors.forename: He-Kuan
authors.initials: HK
authors.lastname: Luo
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK. dsw1000@cam.ac.uk.
authors.forename: Dominic S
authors.identifier: http://orcid.org/0000-0002-9952-3877
authors.initials: DS
authors.lastname: Wright