Spectroscopic and electrochemical sensing of lanthanides with π-extended chromophores incorporating ferrocenes and a coordinative end.
Spectroscopic and electrochemical sensing of lanthanides with π-extended chromophores incorporating ferrocenes and a coordinative end.
复制标题
DOI：
10.1039/c1dt11031d
复制
发表时间：
2011-11
影响因子：
4
通讯作者：
C. Coluccini;A. Sharma;D. Merli;D. V. Griend;B. Mannucci;D. Pasini
中科院分区：
文献类型：
--
作者：
C. Coluccini;A. Sharma;D. Merli;D. V. Griend;B. Mannucci;D. Pasini
在这项研究中，我们报道了三种新型的“推-拉”发色团的合成和表征，其中多个亚苯基团以二茂铁为供体单元，丙二酸基团为受体单元。这些生色团的光谱和电化学性质随着共轭桥的扩展而变化，从而随HOMO-LUMO带隙的变化而变化。通过UV/Vis，(1)H-核磁共振和循环伏安研究证实，1，3-二羰基单元直接结合到共轭分子结构中，能够配位Lewis酸类阳离子，如稀土元素。当Sc(3+)或Eu(3+)作为三价盐配位时，UV/Vis光谱响应从最小的π延伸到最大的发色团是相当不选择性和非线性的。通过平衡限制因子分析，MeCN中的结合研究给出了logK(A)=1.21到3.07之间的值，并确认了所有情况下主体：客体络合物的1：1化学计量比。另一方面，循环伏安法显示，对于两个较短的生色团，Ln(3+)(Eu(3+)，但也测试了Lu(3+)和Er(3+))对Sc(3+)配位的反应具有选择性，而具有最长π桥的配体能够选择性地检测Er(3+)(ΔE(1/2)络合/非络合生色团=20 mV)。
In this study, we report the synthesis and characterization of three novel "push-pull" chromophores, in which multiple phenylenevinylene units are endcapped by ferrocene as donor units and malonate moieties as acceptor units. These chromophores have spectroscopic and electrochemical characteristics which consistently change according to the extension of the conjugated bridge, thus to the variation of the HOMO-LUMO band gap. The 1,3-dicarbonyl units, directly incorporated into the conjugated molecular structures, are able to coordinate Lewis acid-like cations, such as lanthanides, as confirmed by UV/Vis, (1)H NMR and cyclic voltammetry studies. The UV/Vis spectroscopic response upon complexation with Sc(3+) or Eu(3+) as the triflate salts is rather unselective and nonlinear in going from the least to the most π-extended chromophore. Binding studies in MeCN, analyzed via equilibrium-restricted factor analysis, give values between log K(a) = 1.21 and 3.07 and affirm a 1 : 1 stoichiometry of the host:guest complexes in all cases. On the other hand, cyclic voltammetry reveals a selectivity in the response to Sc(3+) coordination over Ln(3+) (Eu(3+), but also Lu(3+) and Er(3+) were tested) for the two shorter chromophores, whereas the ligand with the longest π-bridge is able to sense Er(3+) (ΔE(1/2) complexed/uncomplexed chromophore = 20 mV) selectively over the other lanthanides.