中心为氨基、末端为硝基的苯乙炔树枝状分子的合成

将固定相合成与“收敛/发散”方法相结合,合成了第一、二代苯乙炔树枝状分子.通过Heck-Cassar-Sonogashira-Hagihara偶联反应,将其中心和末端分别修饰上供电子的氨基和拉电子的硝基,得到第一、二代中心为氨基、末端为硝基的苯乙炔树枝状分子NH₂-G1-(NO₂)₂和NH₂-G2-(NO₂)₄.用傅里叶变换红外光谱跟踪了整个固定相合成过程.苯乙炔树枝状分子的紫外-可见吸收光谱呈现出规律性变化.

Synthesis of Amino-centered, Nitro-capped Phenylacetylene-monodendrons

A rapid and convenient solid-supported iterative divergent/convergent approach was utilized to prepare the nitro-capped phenylacetylene-monodendrons I-G1-(NO2)2 and I-G2-(NO2)4, which were transformed into the expected amino-centered, nitro-capped monodendrons NH2-G1-(NO2)2 and NH2-G2-(NO2)4 by Heck-Cassar-Sonogashira-Hagihara coupling reactions. Transmittance FTIR spectroscopy followed the whole solid-phase approach. The absorption peaks at 2 157(1) and 3 311(1) cm-1 were the characteristic of the stretching vibration for the carbon-carbon triple bond in trimethylsilyl-protected acetylene and the carbon-hydrogen bond in the terminal acetylene after desilylation, respectively. Upon coupling reaction, the peak at 1 343(1) cm-1 was observed in P-G1-(NO2)2 and P-G2-(NO2)4, which was the characteristic of the stretching vibration for the terminal nitro groups. Both NH2-G1-(NO2)2 and NH2-G2-(NO2)4 were confirmed by UV-Vis, IR, NMR, EI-MS and ESI-MS techniques. UV-Vis spectra of the obtained monodendrons showed a good relationship with their structures. Both I-G2-(NO2)4 and NH2-G2-(NO2)4 showed a blue shift of (20±1) nm for the absorption peaks, compared with those of I-G1-(NO2)2 and NH2-G1-(NO2)2, which is probably due to the increase in the number of the terminal nitro groups. Upon coupling with the electron donor-amino group, both NH2-G1-(NO2)2 and NH2-G2-(NO2)4 showed a red shift of (6±1) nm for the absorption peaks, compared with those of I-G1-(NO2)2 and I-G2-(NO2)4.