Dipartimento di Chimica G. Ciamician and Centro Interuniversitario per la Conversione Chimica dell'Energia Solare, Università di Bologna, via Selmi 2, I-40126, Bologna, Italy.
Dalton Trans. 2011 Feb 14;40(6):1356-64. doi: 10.1039/c0dt01202e. Epub 2010 Dec 22.
Complexation of Zn(II) ions by cyclam cored dendrimers appended with four (G0), eight (G1) and 16 naphthyl chromophores (G2) at the periphery have been investigated in CH₃CN-CH₂Cl₂ 1 : 1 (v/v) solution by absorption and emission, ESI-mass and ¹H NMR spectroscopy. The results obtained can be interpreted by the formation of complexes of 2 : 1 dendrimer to metal stoichiometry, at low metal ion concentration, and 1 : 1 complexes upon further addition of Zn(II) ions, for all the dendrimer generations. Upon addition of a molecular clip C²⁻ consisting of two anthracene sidewalls bridged by a benzene group with two sulfate substituents in the para positions, heteroleptic complexes of general formula [GnZnC] are formed. Interestingly, in these complexes, a very efficient quenching (practically 100%) of the dendrimer naphthyl luminescence and sensitization (ca. 90%) of the clip anthracene emission take place. The complex [G2ZnC] exhibits a very high molar absorption coefficient in the UV spectral region owing to the 16 naphthyl chromophores of the dendrimer and the two anthracene units of the clip (ε = 1.7 × 10⁵ M⁻¹ cm⁻¹ at 263 nm). Furthermore, the excitation energy absorbed by the naphthyl chromophores is efficiently funneled to the two anthracene units of the clip, which emits in the blue spectral region.
在 CH₃CN-CH₂Cl₂ 1:1（v/v）溶液中，通过吸收和发射光谱、ESI-质谱和 ¹H NMR 光谱研究了在支化聚轮烷的外围连接有四个（G0）、八个（G1）和 16 个萘基发色团（G2）的环脒核心与 Zn(II)离子的络合作用。在低金属离子浓度下，形成了 2:1 树状大分子与金属的化学计量比的配合物，进一步加入 Zn(II)离子时，对于所有的树状大分子生成 1:1 配合物。加入一个由两个蒽基侧壁通过苯基团桥接的分子夹 C²⁻，在对位有两个硫酸酯取代基，形成了通式为[GnZnC]的杂配配合物。有趣的是，在这些配合物中，树状大分子的萘基发光被非常有效地猝灭（实际上是 100%），而夹的蒽基发射被敏化（约 90%）。由于树状大分子的 16 个萘基发色团和夹的两个蒽基单元，配合物[G2ZnC]在紫外光谱区具有非常高的摩尔吸收系数（ε=1.7×10⁵ M⁻¹ cm⁻¹，在 263nm 处）。此外，由萘基发色团吸收的激发能有效地被传递到夹的两个蒽基单元，它们在蓝色光谱区发射。
