[Cr(ddpd)2]3+: A Molecular, Water-Soluble, Highly NIR-Emissive Ruby Analogue
[Cr(ddpd)2]3+: A Molecular, Water-Soluble, Highly NIR-Emissive Ruby Analogue
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DOI：
10.1002/anie.201504894
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发表时间：
2015-09-21
影响因子：
16.6
通讯作者：
Heinze, Katja
中科院分区：
文献类型：
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作者：
Otto, Sven;Grabolle, Markus;Heinze, Katja
第一行过渡金属配合物的明亮、长寿命发射是非常具有挑战性的。在此，我们提出了一种依赖于能级合理调整的新策略。借助三齿配体ddpd（N,N'-二甲基-N,N'-二吡啶-2-基吡啶-2,6-二胺）的大N-Cr-N咬角及其强大的σ供体能力，可以在铬（III）络合物[Cr(ddpd)(2)](3+)中引入非常大的配体场分裂，从而改变失活和光反应性T-4(2) 态远高于发射 E-2 态。防止从 E-2 到 T-4(2) 态的反系间跨越使得这种 3d 金属配合物具有极高的近红外磷光量子产率和寿命。配合物 [Cr(ddpd)(2)](BF4)(3) 具有高度水溶性，并且对热和光诱导的取代反应非常稳定，可用于近红外中基于荧光强度和寿命的氧传感。
Bright, long-lived emission from first-row transition-metal complexes is very challenging to achieve. Herein, we present a new strategy relying on the rational tuning of energy levels. With the aid of the large N-Cr-N bite angle of the tridentate ligand ddpd (N, N'-dimethyl-N, N'-dipyridine-2-ylpyridine-2,6-diamine) and its strong sigma-donating capabilities, a very large ligand-field splitting could be introduced in the chromium(III) complex [Cr(ddpd)(2)](3+), that shifts the deactivating and photoreactive T-4(2) state well above the emitting E-2 state. Prevention of back-intersystem crossing from the E-2 to the T-4(2) state enables exceptionally high near-infrared phosphorescence quantum yields and lifetimes for this 3d metal complex. The complex [Cr(ddpd)(2)](BF4)(3) is highly water-soluble and very stable towards thermal and photo-induced substitution reactions and can be used for fluorescence intensity-and lifetime-based oxygen sensing in the NIR.