Baca Svetlana G, Adams Harry, Sykes Daniel, Faulkner Stephen, Ward Michael D
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Dalton Trans. 2007 Jun 21(23):2419-30. doi: 10.1039/b702235b.
A series of cyanide-bridged coordination networks has been prepared which contain Ru(phen)(CN)4 anions, Ln(III) cations, and additional oligopyridine ligands (1,10-phenanthroline, 2,2':6',2'''-terpyridine or 2,2'-bipyrimidine) which coordinate to the Ln(III) centres. Five structural types have been identified and examples of each type of structure are described: these are hexanuclear Ru4Ln2 clusters; two-dimensional Ru-Ln sheets with a honeycomb pattern of edge-linked Ru6Ln6 hexagons; one-dimensional chains consisting of two parallel cross-linked strands in a ladder-like arrangement; simple single-stranded chains of alternating Ru/Ln components; and a one-dimensional 'chain of squares' in which Ru2Ln2 squares are linked by bipyrimidine bridging ligands which connect to the Ln(III) corners of adjacent squares in the sequence. The 3MLCT luminescence characteristic of the Ru(phen)(CN)4 units is quenched in those networks containing Ln(III) which have low-lying near-infrared luminescent f-f states [Pr(III), Nd(III), Er(III), Yb(III)], with sensitised Ln(III)-based near-IR luminescence generated by d --> f energy-transfer. The rate of d --> f energy-transfer, and hence the degree of quenching of the 3MLCT luminescence from the Ru(phen)(CN)4 units, depends on the availability of f-f levels of an appropriate energy on the Ln(III) centre, with Nd(III) (with a high density of low-lying f-f states) being the most effective energy-acceptor and Yb(III) (with a single low-lying f-f state) being the least effective. Rates of d --> f energy-transfer to different Ln(III) centres could be determined from both the residual (partially quenched) lifetimes of the 3MLCT luminescence, and--in the case of the Yb(III) networks--by a rise-time for the sensitised near-IR luminescence. The presence of the 'blocking' polypyridyl ligands, which reduced the number of cyanide and water ligands that would otherwise coordinate to the Ln(III) centres, resulted in increases in the Ln(III)-based emission lifetimes compared to networks where these blocking ligands were not used.
已经制备了一系列氰基桥联的配位网络，其中包含[Ru(phen)(CN)₄]²⁻阴离子、Ln(III)阳离子以及与Ln(III)中心配位的额外寡吡啶配体（1,10-菲咯啉、2,2':6',2'''-三联吡啶或2,2'-联嘧啶）。已鉴定出五种结构类型，并描述了每种结构类型的示例：这些是六核Ru₄Ln₂簇；具有边缘连接的Ru₆Ln₆六边形蜂窝图案的二维Ru-Ln片层；由两个平行交联链以梯状排列组成的一维链；交替的Ru/Ln组分的简单单链；以及一维“方形链”，其中Ru₂Ln₂方形通过联嘧啶桥联配体连接，这些配体按顺序连接到相邻方形的Ln(III)角上。在含有具有低能近红外发光f-f态的Ln(III)的那些网络中，[Ru(phen)(CN)₄]²⁻单元的3MLCT发光特性被猝灭，[Pr(III)、Nd(III)、Er(III)、Yb(III)]，通过d→f能量转移产生基于Ln(III)的敏化近红外发光。d→f能量转移的速率，以及因此来自[Ru(phen)(CN)₄]²⁻单元的3MLCT发光的猝灭程度，取决于Ln(III)中心上具有适当能量的f-f能级的可用性，Nd(III)（具有高密度的低能f-f态）是最有效的能量受体，而Yb(III)（具有单个低能f-f态）是最无效的。d→f能量转移到不同Ln(III)中心的速率可以从3MLCT发光的剩余（部分猝灭）寿命以及——在Yb(III)网络的情况下——通过敏化近红外发光的上升时间来确定。“阻断”多吡啶配体配体配体的存在减少了原本会与Ln(III)中心配位的氰化物和水配体的数量，与未使用这些阻断配体的网络相比，导致基于Ln(III)的发射寿命增加。
