State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210093 , P. R. China.
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210093 , P. R. China.
Anal Chem. 2020 Jan 7;92(1):1268-1275. doi: 10.1021/acs.analchem.9b04431. Epub 2019 Dec 13.
The realization of electrochemiluminescence (ECL) detection at the single-molecule level is a longstanding goal of ECL assay that requires a novel ECL probe with significantly enhanced luminescence. Here, the synergistic effect of electrochemiluminescence (ECL) is observed unprecedentedly in a new cyclometalated dinuclear Ir(III) complex [Ir(dfppy)(imiphenH)]PF (·PF, PF = hexafluorophosphate) in which two {Ir(dfppy)} units are bridged by an imiphenH ligand. The ECL intensity from complex ·PF is 4.4 and 28.7 times as high as that of its reference mononuclear complexes and ·PF, respectively. Theoretical calculation reveals that the S to S excitation is a local excitation in ·PF with two electron-coupled Ir(III) centers, which contributes to the enhanced ECL. The synergistic effect of ECL in ·PF can be used to detect microRNA 21 at the single-molecule level (microRNA 21: UAGCUUAUCAGACUGAUGUUGA), with detectable ECL emission from this complex intercalated in DNA/microRNA 21 duplex as low as 90 helix molecules. The finding of the synergistic effect of ECL will not only provide a novel strategy for the modulation of ECL intensity but also enable the detection of microRNA at the single-molecule level.
电致化学发光（ECL）在单分子水平上的实现是 ECL 分析的一个长期目标，需要一种新型的 ECL 探针，具有显著增强的发光。在这里，在一个新的环金属化双核 Ir(III)配合物[Ir(dfppy)(imiphenH)]PF（·PF，PF = 六氟磷酸根）中，观察到电致化学发光（ECL）协同效应前所未有，其中两个{Ir(dfppy)}单元通过一个 imiphenH 配体桥接。配合物·PF 的 ECL 强度分别比其参考单核配合物[Ir(dfppy)2(phen)]PF 和[Ir(dfppy)(imiphen)]PF 的 ECL 强度高 4.4 和 28.7 倍。理论计算表明，在·PF 中，S 到 S 的激发是两个电子耦合的 Ir(III)中心的局部激发，这有助于增强 ECL。·PF 中的 ECL 协同效应可用于在单分子水平上检测 microRNA 21（microRNA 21：UAGCUUAUCAGACUGAUGUUGA），该配合物插入 DNA/microRNA 21 双链体中时，可检测到的 ECL 发射低至 90 个螺旋分子。ECL 协同效应的发现不仅为调节 ECL 强度提供了一种新策略，而且还能够实现单分子水平上的 microRNA 检测。
