Alkyl chain functionalised, cyclometalated platinum(II) complexes: Syntheses, luminescence properties and X-ray crystal structure

• Synthesis of alkyl chain adorned 2-phenylquinoline ligands.
• Synthesis of lipophilic cyclometalated Pt(II) complexes.
• Long-lived luminescence from Pt(II) complexes in solution.

The synthesis and characterisation of nine new monometallic heteroleptic platinum complexes [PtCl(L1–3)(DMSO)], [Pt(L1–3)(acac)], [Pt(L1–3)(8-Q)] (where L1–3 = N-octyl/dodecyl/hexadecyl-2-phenylquinoline-4-carboxamides; acac = acetylacetonate; 8-Q = 8-quinolinato) are described. Single crystal X-ray diffraction studies on [Pt(L1)(acac)] revealed a square planar coordination geometry with intermolecular Pt–Pt contacts at ca. 3.3 Å. The complexes were investigated using 195Pt{1H} NMR spectroscopy, revealing varied chemical shifts around δPt −2800 ppm that were strongly dependent upon the specific coordination environment of Pt(II). Luminescence studies showed the complexes possess a phosphorescent character with tuneable emission wavelengths between 605 and 641 nm, and luminescent lifetimes up to ca. 450 ns. Supporting TD-DFT studies provided descriptions of the HOMO and LUMO energy levels of the key complex types, which generally correlated well with the experimental spectra. The contribution of the Pt(5d) centre to the calculated HOMOs was strongly ligand dependent, whilst the LUMOs were generally predicted to be localized over the quinoline component of the cyclometalated ligand.

Figure optionsDownload as PowerPoint slide