Newly designed luminescent di- and tetra-nuclear double rollover cycloplatinated(II) complexes

• The work investigates the synthesis and characterization of new double roll-over di- and tetra-nuclear platinum complexes.
• The complexes are strongly luminescent in both solution and solid state.
• The photophysical properties of the complexes, supported by theoretical calculation, were investigated.

The known binuclear complex [Pt2(μ-bpy-2H)(Me)2(DMSO)2], 1, in which bpy = 2,2′-bipyridine and DMSO = dimethyl sulfoxide, was reacted with 2 equiv bis(diphenylphosphino)methane, dppm, to give the new double rollover cycloplatinated(II) complex [Pt2(μ-bpy-2H)(Me)2(κ1-dppm)2], 2, in which each metallic center bears a monodentate dppm ligand. The reaction of 2 with 2 equiv of the known monomeric cycloplatinated (II) complex [Pt(Me)(bhq-H)(SMe2)], in which bhq = 7,8-benzo[h]quinoline, gave the new unsymmetrical tetranuclear complex [{(bhq-H)(Me)Pt(μ-dppm)Pt(Me)}2(μ-bpy-2H)], 3. The complexes were fully characterized using multinuclear (1H and 31P{1H}) NMR spectroscopy and elemental analysis. Photophysical properties of the synthesized complexes were investigated and the results were confirmed by DFT calculations. The complexes 1–3 are brightly luminescent in solution and solid state. The complex 1 exhibits structured emission band, complying with the cyclometalated ligand being the centered emissive state. The complexes 2 and 3, however, exhibit unstructured emission bands, confirming a large amount of MLCT in their emissive states.

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