Ronson Tanya K, Lazarides Theodore, Adams Harry, Pope Simon J A, Sykes Daniel, Faulkner Stephen, Coles Simon J, Hursthouse Michael B, Clegg William, Harrington Ross W, Ward Michael D
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Chemistry. 2006 Dec 13;12(36):9299-313. doi: 10.1002/chem.200600698.
The complexes [Pt(bipy){CC-(4-pyridyl)}(2)] (1) and [Pt(tBu(2)bipy){CC-(4-pyridyl)}(2)] (2) and [Pt(tBu(2)-bipy)(CC-phen)(2)] (3) all contain a Pt(bipy)(diacetylide) core with pendant 4-pyridyl (1 and 2) or phenanthroline (3) units which can be coordinated to {Ln(diketonate)(3)} fragments (Ln = a lanthanide) to make covalently-linked Pt(II)/Ln(III) polynuclear assemblies in which the Pt(II) chromophore, absorbing in the visible region, can be used to sensitise near-infrared luminescence from the Ln(III) centres. For 1 and 2 one-dimensional coordination polymers 1Ln(tta)(3) and 2Ln(hfac)(3) are formed, whereas 3 forms trinuclear adducts [3{Ln(hfac)(3)}(2)] (tta=anion of thenoyl-trifluoroacetone; hfac=anion of hexafluoroacetylacetone). Complexes 1-3 show typical Pt(II)-based (3)MLCT luminescence in solution at approximately 510 nm, but in the coordination polymers 1Ln(tta)(3) and 2Ln(hfac)(3) the presence of stacked pairs of Pt(II) units with short PtPt distances means that the chromophores have (3)MMLCT character and emit at lower energy ( approximately 630 nm). Photophysical studies in solution and in the solid state show that the (3)MMLCT luminescence in 1Ln(tta)(3) and 2Ln(hfac)(3) in the solid state, and the (3)MLCT emission of [3{Ln(hfac)(3)}(2)] in solution and the solid state, is quenched by Pt-->Ln energy transfer when the lanthanide has low-energy f-f excited states which can act as energy acceptors (Ln=Yb, Nd, Er, Pr). This results in sensitised near-infrared luminescence from the Ln(III) units. The extent of quenching of the Pt(II)-based emission, and the Pt-->Ln energy-transfer rates, can vary over a wide range according to how effective each Ln(III) ion is at acting as an energy acceptor, with Yb(III) usually providing the least quenching (slowest Pt-->Ln energy transfer) and either Nd(III) or Er(III) providing the most (fastest Pt-->Ln energy transfer) according to which one has the best overlap of its f-f absorption manifold with the Pt(II)-based luminescence.
配合物[Pt(bipy){CC-(4-吡啶基)}(2)] (1)、[Pt(tBu(2)bipy){CC-(4-吡啶基)}(2)] (2)和[Pt(tBu(2)-bipy)(CC-菲咯啉)(2)] (3)均含有一个Pt(bipy)(二乙炔基)核心，带有可与{Ln(二酮)(3)}片段（Ln = 镧系元素）配位的侧基4-吡啶基（1和2）或菲咯啉（3）单元，以形成共价连接的Pt(II)/Ln(III)多核组装体，其中在可见光区域吸收的Pt(II)发色团可用于敏化来自Ln(III)中心近红外发光。对于1和2，形成了一维配位聚合物1Ln(tta)(3)和2Ln(hfac)(3)，而3形成了三核加合物[3{Ln(hfac)(3)}(2)]（tta = 噻吩甲酰三氟丙酮的阴离子；hfac = 六氟乙酰丙酮的阴离子）。配合物1 - 3在溶液中于约510 nm处显示出典型的基于Pt(II)的(3)MLCT发光，但在配位聚合物1Ln(tta)(3)和2Ln(hfac)(3)中，具有短Pt - Pt距离的成对堆叠的Pt(II)单元的存在意味着发色团具有(3)MMLCT特征并在较低能量（约630 nm）处发射。溶液和固态的光物理研究表明，当镧系元素具有可作为能量受体的低能量f - f激发态时（Ln = Yb、Nd、Er、Pr），固态1Ln(tta)(3)和2Ln(hfac)(3)中的(3)MMLCT发光以及溶液和固态[3{Ln(hfac)(3)}(2)]中的(3)MLCT发射会因Pt→Ln能量转移而猝灭。这导致了来自Ln(III)单元的敏化近红外发光。基于Pt(II)的发射的猝灭程度以及Pt→Ln能量转移速率可根据每个Ln(III)离子作为能量受体的有效性在很宽的范围内变化，Yb(III)通常提供最少的猝灭（最慢的Pt→Ln能量转移），而Nd(III)或Er(III)根据其f - f吸收多重态与基于Pt(II)的发光的重叠程度提供最多的猝灭（最快的Pt→Ln能量转移）。
