Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Kolkata 700 032, India.
Dalton Trans. 2014 Mar 7;43(9):3767-82. doi: 10.1039/c3dt52424h.
A mixed-ligand monometallic ruthenium(ii) complex of composition (bipy)2Ru(tpy-Hbzim-dipy)2 (), where tpy-Hbzim-dipy = 4'-[4-(4,5-di-pyridin-2-yl-1H-imidazol-2-yl)-phenyl]-[2,2';6',2'']terpyridine and bipy = 2,2'-bipyridine has been synthesized and characterized using standard analytical and spectroscopic techniques including X-ray crystallography. The complex displays very intense, ligand centered absorption bands in the UV and moderately intense MLCT bands in the visible region. On excitation at the MLCT bands, the complex exhibits strong luminescence at room temperature with lifetimes in the range of 116-257 ns, depending upon the nature of the solvents. The complex is found to undergo one reversible oxidation in the positive potential window (0 to +1.8 V) and two successive quasi-reversible reductions in the negative potential window (0 to -2.0 V). Both anion and cation binding properties of the receptor were thoroughly investigated in acetonitrile solution using (1)H NMR, absorption, steady state and time-resolved emission spectral studies and by cyclic voltammetry. The anion sensing studies revealed that the receptor acts as a "turn on" luminescence sensor for H2PO4(-) and HSO4(-) ions, and as a "turn off" sensor for F(-) and AcO(-) ions. It is evident that in the presence of excess F(-) and AcO(-) ions, deprotonation of the imidazole N-H fragment of the receptor occurs, an event which is signaled by the change of color from orange yellow to red visible to the naked eye. On the other hand, the probable mode of interaction of the receptors with H2PO4(-) and HSO4(-) ions is through hydrogen bonding interaction. The cation-sensing properties showed that the receptor was found to exhibit a colorimetric sensing ability that was highly selective for Fe(2+), as evidenced by the distinct color change from yellow orange to deep red-violet to the naked eye over the other cations studied (Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Hg(2+)).
一种组成为(bipy)2Ru(tpy-Hbzim-dipy)2 ()的混合配体单核钌(ii)配合物，其中 tpy-Hbzim-dipy = 4'-[4-(4,5-二吡啶-2-基-1H-咪唑-2-基)-苯基]-[2,2';6',2'']三联吡啶，bipy = 2,2'-联吡啶，已经通过标准分析和光谱技术（包括 X 射线晶体学）合成和表征。该配合物在紫外区显示出非常强的、配体中心的吸收带，在可见区显示出中等强度的 MLCT 带。在 MLCT 带激发下，该配合物在室温下表现出强发光，寿命范围为 116-257 ns，取决于溶剂的性质。该配合物在正电势窗口（0 至 +1.8 V）中经历一个可逆氧化，在负电势窗口（0 至 -2.0 V）中经历两个连续的准可逆还原。使用 (1)H NMR、吸收、稳态和时间分辨发射光谱研究以及循环伏安法，在乙腈溶液中彻底研究了受体的阴离子和阳离子结合性质。阴离子传感研究表明，该受体是 H2PO4(-)和 HSO4(-)离子的“开启”发光传感器，而 F(-)和 AcO(-)离子的“关闭”传感器。显然，在存在过量 F(-)和 AcO(-)离子的情况下，受体的咪唑 N-H 片段发生去质子化，这一事件通过肉眼可见的橙色黄色到红色的颜色变化来指示。另一方面，受体与 H2PO4(-)和 HSO4(-)离子相互作用的可能模式是通过氢键相互作用。阳离子传感性质表明，该受体表现出对 Fe(2+)的高选择性比色传感能力，这一点可以通过肉眼可见的从黄色橙色到深红紫色的明显颜色变化来证明，而对研究的其他阳离子（Mn(2+)、Fe(3+)、Co(2+)、Ni(2+)、Cu(2+)、Zn(2+)、Cd(2+)和 Hg(2+)）则没有这种变化。
