Sensitized Near-Infrared Emission from Complexes of Yb~(III),Nd~(III)and Er~(III)by Energy-Transfer from Covalently Attached Pt~(II)-Based Antenna Units

摘要

A series of dinuclear platinum(II)-lanthanide(III)complexes has been prepared in which a square-planar Pt~(II)unit,either [(PPh_3)_2Pt(pdo)](H_2pdo=5,6-dihydroxyphenanthroline)or [Cl_2Pt(dppz)][dppz=2,3-bis(2-pyridyl)pyrazine],is connected to a {Ln(dik)_3}unit ("dik"=a 1,3-diketoate ligand).The mononuclear complexes [(PPh_3)_2Pt(pdo)]and [Cl_2Pt(dppz)]both have external,vacant N,N-donor diimine-type binding sites that react with various [Ln(dik)_3(H_2O)_2]units to give complexes [(PPh_3)_2Pt(mu-pdo)Ln(tta)_3](series A;Htta=thenoyltrifluoroacetone),[Cl_2Pt(mu-dppz)Ln(tta)_3](series B);and [Cl_2Pt(mu-dppz)Ln(btfa)_3](series C;Hbtfa=benzoyltrifluoroacetone);in all of these the lanthanide centres are eight-coordiante.The lanthanides used exhibit near-infrared luminescence (Nd,Yb,Er).Crystal structures of members of each series are described.In all complexes,excitation into the Pt-centred absorption band (at 520 nm for series A complexes:440 nm for series B and C complexes)results in characteristic near-IR luminescence from the Nd,Yb or Er centres in botht he solid state and in CH_2Cl_2,following energy-transfer from the Pt antenna chromophore.This work demonstrates how d-block-derived chromohore,with thier intense and tunable electronic transitions,can be used as sensitisers to achieve near-infrared luminescence from lanthanides in suitably designed heterodinuclear complexes bansed on simle bridging ligands.