We have synthesized a novel dendrimer (1) based on two covalently linked cyclam units as a core appended to six branches, each one consisting of one dimethoxybenzene and two naphthyl units (cyclam = 1,4,8,11-tetraazacyclotetradecane). Such a dendrimer shows three fluorescence bands which can be assigned to naphthyl localized excited states (λmax
= 336 nm), naphthyl excimers (λmaxca. 390 nm), and naphthyl–amine exciplexes (λmax
= 510 nm). Protonation or complexation of the bis-cyclam core with Zn2+ does not affect the absorption spectrum of the dendrimer, but causes noticeable changes in the fluorescence intensity of the three component bands. Complexation with Cu2+ not only causes changes in the relative intensities of the fluorescence bands, but also the appearance of a new absorption band in the near UV spectral region. Analysis of the titration curves has allowed us to obtain clear evidence for the formation of 1 : 1 (1(H+), [Zn(1)]2+, [Cu(1)]2+) and 2 : 1 (1(2H+), [Zn2(1)]4+, [Cu2(1)]4+) species. Comparison with the behaviour of a previously investigated parent monocyclam dendrimer (2) suggests that in the 1 : 1 species of 1 both the cyclam units are involved in the complexation with Zn2+ and Cu2+.
我们合成了一种新型树枝状聚合物 (1),其基于两个共价连接的 cyclam 单元作为核心,附加有六个分支,每个分支由一个二
甲氧基苯和两个
萘基单元组成(cyclam =
1,4,8,11-四氮杂环十四烷)。这种树枝状聚合物显示出三个荧光带,这些荧光带可归属于
萘基局域激发态(λmax
= 336 nm)、
萘基准分子 (λmaxca. 390 nm) 和
萘基胺激基复合物 (λmax
= 510 纳米)。双环酰胺核与 Zn2+ 的质子化或络合不会影响树枝状聚合物的吸收光谱,但会导致三个组分谱带的荧光强度发生明显变化。与 Cu2+ 的络合不仅会导致荧光带相对强度的变化,还会在近紫外光谱区出现新的吸收带。滴定曲线的分析使我们能够获得 1 : 1 (1(H+)、[Zn(1)]2+、[Cu(1)]2+) 和 2 : 1 (1( 2H+)、[Zn2(1)]4+、[Cu2(1)]4+) 种。与先前研究的母体单环化合物树枝状聚合物 (2) 的行为进行比较表明,在 1 的 1:1 物种中,两个仙客来单元均参与与 Zn2+ 和 Cu2+ 的络合。