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Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties

Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties
Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties
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 ?Ptca. -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 ? ?*) 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 (? = 42 ?s) under degassed solvent conditions, suggestive of energy transfer processes between the two states.
0300-9246
10297-10307
Stacey, Oliver J.
be15a0dd-6efe-4fa0-95da-3694e9a6cee6
Ward, Benjamin D.
3fe8307c-f34a-4469-97fc-2b335ed5fb7d
Coles, Simon
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Horton, Peter
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Pope, Simon J.A.
db9a489c-29ba-41cd-a96a-623bace0889d
Stacey, Oliver J.
be15a0dd-6efe-4fa0-95da-3694e9a6cee6
Ward, Benjamin D.
3fe8307c-f34a-4469-97fc-2b335ed5fb7d
Coles, Simon
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Horton, Peter
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Pope, Simon J.A.
db9a489c-29ba-41cd-a96a-623bace0889d

Stacey, Oliver J., Ward, Benjamin D., Coles, Simon, Horton, Peter and Pope, Simon J.A. (2016) Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties. Dalton Transactions, 45 (25), 10297-10307. (doi:10.1039/c6dt01335j). (PMID:27241625)

Record type: Article

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 ?Ptca. -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 ? ?*) 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 (? = 42 ?s) under degassed solvent conditions, suggestive of energy transfer processes between the two states.

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Accepted/In Press date: 24 May 2016
e-pub ahead of print date: 31 May 2016
Published date: 7 July 2016

Identifiers

Local EPrints ID: 400227
URI: http://eprints.soton.ac.uk/id/eprint/400227
ISSN: 0300-9246
PURE UUID: 53be0d1a-d656-4768-baa0-ef204cf3cb82
ORCID for Simon Coles: ORCID iD orcid.org/0000-0001-8414-9272
ORCID for Peter Horton: ORCID iD orcid.org/0000-0001-8886-2016

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Date deposited: 13 Sep 2016 10:42
Last modified: 15 Mar 2024 05:53

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Contributors

Author: Oliver J. Stacey
Author: Benjamin D. Ward
Author: Simon Coles ORCID iD
Author: Peter Horton ORCID iD
Author: Simon J.A. Pope

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