title: Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties.
abstract: Ligands based upon 4-carboxamide-2-phenylquinoline derivatives have been synthesised with solubilising octyl hydrocarbon chains and tethered aromatic chromophores to give naphthyl (), anthracenyl () and pyrenyl () ligand variants, together with a non-chromophoric analogue () for comparison. (1)H NMR spectroscopic studies of the ligands showed that two non-interchangeable isomers exist for and while only one isomer exists for and . Supporting DFT calculations on suggest that the two isomers may be closely isoenergetic with a relatively high barrier to exchange of ca. 100 kJ mol(-1). These new ligands were cyclometalated with Pt(ii) to give complexes [Pt()(acac)] (acac = acetylacetonate). The spectroscopically characterised complexes were studied using multinuclear NMR spectroscopy including (195)Pt{(1)H} NMR studies which revealed δPtca. -2785 ppm for [Pt()(acac)]. X-ray crystallographic studies were undertaken on [Pt()(acac)] and [Pt()(acac)], each showing the weakly distorted square planar geometry at Pt(ii); the structure of [Pt()(acac)] showed evidence for intermolecular Pt-Pt interactions. The UV-vis. absorption studies show that the spectral profiles for [Pt()(acac)] are a composite of the organic chromophore centred bands and a broad (1)MLCT (5d → π*) band (ca. 440 nm) associated with the complex. Luminescence studies showed that complexes [Pt()(acac)] are dual emissive with fluorescence characteristic of the tethered fluorophore and long-lived phosphorescence attributed to (3)MLCT emission. In the case of the pyrenyl derivative, [Pt()(acac)], the close energetic matching of the (3)MLCT and (3)LCpyr excited states led to an elongation of the (3)MLCT emission lifetime (τ = 42 μs) under degassed solvent conditions, suggestive of energy transfer processes between the two states.
authors.affiliation: School of Chemistry, Main Building. and Cardiff University, Cardiff CF10 3AT, UK. popesj@cardiff.ac.uk.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Stacey
authors.affiliation: School of Chemistry, Main Building. and Cardiff University, Cardiff CF10 3AT, UK. popesj@cardiff.ac.uk.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Ward
authors.affiliation: K National Crystallographic Service, Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, England, UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Coles
authors.affiliation: K National Crystallographic Service, Chemistry, Faculty of Natural and Environmental Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, England, UK.
authors.forename: Peter N
authors.initials: PN
authors.lastname: Horton
authors.affiliation: School of Chemistry, Main Building. and Cardiff University, Cardiff CF10 3AT, UK. popesj@cardiff.ac.uk.
authors.forename: Simon J A
authors.initials: SJ
authors.lastname: Pope