作者:Per Antoni、Michael Malkoch、George Vamvounis、Daniel Nyström、Andreas Nyström、Mikael Lindgren、Anders Hult
DOI:10.1039/b802197j
日期:——
Dendrimers up to the fourth generation (G1–G4) were successfully synthesized via the efficient copper catalyzed 1,3-dipolar cycloaddition between primary alkynes and azides (CuAAC), also referred to as a click reaction. The synthetic protocol involved the preparation of presynthesized dendron wedges that subsequently were attached to a tetra-valent alkyne functional cyclen core. These constructed structures integrated stable triazole groups “intra-locked” between the cyclen and dendron wedges. The incorporation of a lanthanide metal ion, europium, into the interior of all cyclen dendrimers was monitored by FT-IR. Interestingly, the photophysical results showed that the proximate triazole not only acts as a stable linker but also as a sensitizers, transferring its singlet–singlet excitation in the ultraviolet region (270–290 nm) to the partially filled luminescent lanthanide 4f shell. An increase of luminescence decay time from the lanthanide 5D0 → 7F2 emission was observed with increasing dendrimer size, indicating that the shielding effect of the dendron wedges is important for the relaxation of the photo-excitation and energy transfer. To the best of our knowledge, this is the first time a set of dendron wedges have successfully been attached to a cyclen metal ion cage via the versatile click reaction. Furthermore, the produced triazoles intra-locked in close proximity to the macrocycle core elucidated an interesting photophysical function.
通过高效的铜催化伯级炔烃与叠氮化物之间的 1,3-二极环化反应(CuAAC),也称为点击反应,成功合成了第四代(G1-G4)树枝状化合物。合成方案包括制备预合成的树枝状楔形物,然后将其连接到四价炔功能环烯核心上。这些构建的结构将稳定的三唑基团 "内锁 "在环烯和树枝膦楔之间。所有环烯树枝状聚合物的内部都加入了镧系金属离子铕,并通过傅里叶变换红外光谱进行了监测。有趣的是,光物理结果表明,近似的三唑不仅是一种稳定的连接剂,而且还是一种敏化剂,可将其在紫外区(270-290 纳米)的单邢子激发转移到部分填充的发光镧系元素 4f 壳上。随着树枝状聚合物尺寸的增大,观察到镧系元素 5D0 → 7F2 发射的发光衰减时间延长,这表明树枝状楔形体的屏蔽效应对于光激发和能量转移的弛豫非常重要。据我们所知,这是首次通过多功能点击反应成功地将一组树枝状楔形体连接到环状金属离子笼上。此外,生成的三唑内锁紧靠大环核心,阐明了一种有趣的光物理功能。