Two-photon luminescence from polar bis-terpyridyl-stilbene derivatives of Ir(iii) and Ru(ii)
作者:Louise S. Natrajan、Anita Toulmin、Alex Chew、Steven W. Magennis
DOI:10.1039/c0dt00750a
日期:——
Four structurally related iridium(III) and ruthenium(II) complexes bearing two polar terpyridyl–stilbene derived chromophores 4-(4-2-[4-(methoxy)phenyl]ethenyl}phenyl)-2,2′-6′,2′′-terpyridine (ttpyeneanisole) and 4-(4-2-[phenyl]ethenyl}phenyl)-2,2′-6′,2′′-terpyridine (tpystilbene) have been synthesised and characterised in the solid state and in solution. In the solid state, the dihedral angle subtending the pyridyl and tolyl groups of 27.1° in the Ir(III) complex [Ir(ttpyeneanisole)2]·3PF6 is more acute than in the Ru(II) derivative [Ru(tpystilbene)2]·2PF6 (35.5°), indicating the presence of a greater degree of π-delocalisation across the terpyridine unit in the former compound. Their luminescence properties in fluid solution have been investigated following both resonant and non-resonant excitation. We have shown that each of the complexes undergoes two-photon excitation when excited in the near infrared (740 to 820 nm), with two-photon absorption cross sections in the range 11–67 × 10−50 cm4 s photon−1. The larger cross sections for the Ir(III) complexes reflect the differences observed in the solid state. This work therefore demonstrates that such complexes are promising as luminescent markers for 3D imaging and illustrates that simple functionalisation of the chromophores and the choice of metal can lead to marked enhancements in the two-photon cross sections (σ2) compared to those of simpler heteroleptic polypyridyl based derivatives.
四种结构相关的铱(III)和钌(II)配合物含有两种极性萜吡啶-二苯乙烯衍生发色团 4-(4-2-[4-(甲氧基)苯基]乙烯基}苯基)-2,2′-6′、2′′-terpyridine (ttpyeneanisole) 和 4-(4-2-[4-(甲氧基)苯基]乙烯基}苯基)-2,2′-6′,2′′-terpyridine (tpystilbene) 的合成,并对它们在固态和溶液中的特性进行了分析。在固态下,Ir(III) 复合物[Ir(ttpyeneanisole)2]-3PF6 中吡啶基和甲苯基的二面角为 27.1°,比 Ru(II) 衍生物[Ru(ttpystilbene)2]-2PF6(35.5°)中的二面角更尖锐,这表明前者化合物中的特吡啶单元存在更大程度的 π 位移。我们研究了它们在共振和非共振激发下在流体溶液中的发光特性。我们已经证明,每种复合物在近红外(740 至 820 纳米)激发时都会发生双光子激发,双光子吸收截面范围为 11-67 × 10-50 cm4 s 光子-1。Ir(III)配合物的较大截面反映了在固态下观察到的差异。因此,这项研究表明,这类复合物很有希望成为三维成像的发光标记物,并说明发色团的简单官能化和金属的选择可导致双光子截面(σ2)比那些更简单的异性多吡啶基衍生物明显提高。