Daniels Ruth E, McKenzie Luke K, Shewring Jonathan R, Weinstein Julia A, Kozhevnikov Valery N, Bryant Helen E
Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Tyne and Wear NE1 8ST, Newcastle Upon Tyne, UK. Email:
Department of Chemistry, University of Sheffield, Dainton Building, Sheffield S3 7HF, UK.
RSC Adv. 2018 Mar 12;8(18):9670-9676. doi: 10.1039/c8ra00265g. Epub 2018 Mar 6.
A novel diiridium complex [(N^C^N)Ir(bis-N^C)Ir(N^C^N)Cl]PF (N^C^N = 2-[3--butyl-5-(pyridin-2-yl)phenyl]pyridine; bis-N^C = 3,6-bis(4--butylphenyl)pyridazine) was designed, synthesised and characterised. The key feature of the complex is the bridging pyridazine ligand which brings two cyclometallated Ir(iii) metal centres close together so that Cl also acts as a bridging ligand leading to a cationic complex. The ionic nature of the complex offers a possibility of improving solubility in water. The complex displays broad emission in the red region ( = 520-720 nm, = 1.89 μs, = 62% in degassed acetonitrile). Cellular assays by multiphoton ( = 800 nm) and confocal ( = 405 nm) microscopy demonstrate that the complex enters cells and localises to the mitochondria, demonstrating cell permeability. Further, an appreciable yield of singlet oxygen generation ( = 0.45, direct method, by O NIR emission in air equilibrated acetonitrile) suggests a possible future use in photodynamic therapy. However, the complex has relatively high dark toxicity (LD = 4.46 μM), which will likely hinder its clinical application. Despite this toxicity, the broad emission spectrum of the complex and high emission yield observed suggest a possible future use of this class of compound in emission bioimaging. The presence of two heavy atoms also increases the scattering of electrons, supporting potential future applications as a dual fluorescence and electron microscopy probe.
设计、合成并表征了一种新型二铱配合物[(N^C^N)Ir(bis-N^C)Ir(N^C^N)Cl]PF（N^C^N = 2-[3-叔丁基-5-(吡啶-2-基)苯基]吡啶；bis-N^C = 3,6-双(4-叔丁基苯基)哒嗪）。该配合物的关键特征是桥连哒嗪配体，它使两个环金属化的Ir(III)金属中心靠近在一起，从而使Cl也作为桥连配体，形成阳离子配合物。该配合物的离子性质提供了提高在水中溶解度的可能性。该配合物在红色区域显示出宽发射（λ = 520 - 720 nm，τ = 1.89 μs，在脱气乙腈中Φ = 62%）。通过多光子（λ = 800 nm）和共聚焦（λ = 405 nm）显微镜进行的细胞分析表明，该配合物进入细胞并定位于线粒体，证明了细胞通透性。此外，可观的单线态氧生成产率（Φ = 0.45，直接法，通过在空气平衡的乙腈中的O近红外发射）表明其在光动力疗法中可能有未来应用。然而，该配合物具有相对较高的暗毒性（LD = 4.46 μM），这可能会阻碍其临床应用。尽管有这种毒性，但观察到的该配合物的宽发射光谱和高发射产率表明这类化合物在发射生物成像中可能有未来应用。两个重原子的存在也增加了电子散射，支持其作为双荧光和电子显微镜探针的潜在未来应用。
