Highly Luminescent Mixed-Metal Pt(II)/Ir(III) Complexes: Bis-Cyclometalation of 4,6-Diphenylpyrimidine As a Versatile Route to Rigid Multimetallic Assemblies
Highly Luminescent Mixed-Metal Pt(II)/Ir(III) Complexes: Bis-Cyclometalation of 4,6-Diphenylpyrimidine As a Versatile Route to Rigid Multimetallic Assemblies
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DOI：
10.1021/ic200706e
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发表时间：
2011-07-04
影响因子：
4.6
通讯作者：
Williams, J. A. Gareth
中科院分区：
文献类型：
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作者：
Kozhevnikov, Valery N.;Durrant, Marcus C.;Williams, J. A. Gareth
前配体4，6-二（4-叔丁基苯基）嘧啶LH 2可以在两个芳环之一上与K2 PtCl 4进行环铂化反应，用乙酰丙酮钠处理后得到单核配合物Pt（N布尔和C-LH）（acac）（表示为Pt）。如果使用过量的K2 PtCl 4，则得到形式为[Pt（acac）]（2）{mu-（N boolean AND C-L-N boolean AND C）}（Pt-2）的双核配合物，其中嘧啶环充当桥连单元。或者，单核络合物可以用不同的金属离子进行环化。因此，Pt与IrCl 3中心点3 H（2）O（2：1比率）的反应在用乙酰丙酮钠处理后导致Ir{mu-（N布尔与C-L-N布尔与C）Pt（acac）}（2）（acac）（Pt 2 Ir）形式的前所未有的混合金属络合物。还合成了单核铱配合物Ir（Nboolean AND C-LH）（2）（acac）（Ir）。研究了四种配合物及其前配体的紫外-可见吸收和光致发光性质。这些配合物都是高度发光的，在室温下溶液中的量子产率约为0.5。发现额外金属中心的引入导致吸收和发射的显著红移，λ（max）的顺序为Pt < Pt-2 < In <Pt 2 Ir。这一趋势的解释与电化学数据和密度泛函理论计算的帮助下，这表明，红移主要是由于一个渐进的最低未占分子轨道（LUMO）的稳定。辐射衰减常数也增加。这种多功能的设计策略可以提供一种新的方法来调整和优化的d-区金属配合物的发光性能，为当代的应用。
The proligand 4,6-di-(4-tert-butylphenyl)pyrimidine LH2 can undergo cycloplatination with K2PtCl4 at one of the two aryl rings to give, after treatment with sodium acetylacetonate, a mononuclear complex Pt(N boolean AND C-LH)(acac) (denoted Pt). If an excess of K2PtCl4 is used, a dinuclear complex of the form [Pt(acac)](2){mu-(N boolean AND C-L-N boolean AND C)} (Pt-2) is obtained instead, where the pyrimidine ring acts as a bridging unit. Alternatively, the mononuclear complex can undergo cyclometalation with a different metal ion. Thus, reaction of Pt with IrCl3 center dot 3H(2)O (2:1 ratio) leads, after treatment with sodium acetylacetonate, to an unprecedented mixed-metal complex of the form Ir{mu-(N boolean AND C-L-N boolean AND C)Pt(acac)}(2)(acac) (Pt2Ir). The mononuclear iridium complex Ir(N boolean AND C-LH)(2)(acac) (Ir) has also been prepared for comparison. The UV-visible absorption and photoluminesence properties of the four complexes and of the proligand have been investigated. The complexes are all highly luminescent, with quantum yields of around 0.5 in solution at room temperature. The introduction of the additional metal centers is found to lead to a substantial red-shift in absorption and emission, with lambda(max) in the order Pt < Pt-2 < In < Pt2Ir. The trend is interpreted with the aid of electrochemical data and density functional theory calculations, which suggest that the red-shift is due primarily to a progressive stabilization of the lowest unoccupied molecular orbital (LUMO). The radiative decay constant is also increased. This versatile design strategy may offer a new approach for tuning and optimizing the luminescence properties of d-block metal complexes for contemporary applications.