Abstract: 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.

Key words: Solid-phase synthesis, Iterative divergent/convergent, Phenylacetylene-monodendron, Coupling reactions