Polyphenylene dendrimers 11

12 and 13 containing terminal trimethylsilyl groups have been synthesized by phosphine-free palladium chloride catalyzed Suzuki couplings of 1

3

5-tris(3’

5'-dibromophenyl)benzene 9 with aryl boronic acids 5 and 6．These macromolecules were characterized by Fourier transform infrared(FTIR)

nuclear magnetic resonance(NMR)and matrix assisted laser desorption／ionization time of flisht(MALDI-TOF)moss spectra．Gel permeation chromatograph(GPC)indicated that the hydrodynamic radium of 12

with trimethylsiliyl (-TMS)groups substituted at para—positions on its terminal benzene rings

was larger than that of 13．with trimethylsiliyl groups substituted at meta—positions on its terminal benzene rings．X-ray powder diffraction patterns showed that dendrimer 12 was of a certain amount of crystallinity and dendrimer 13 was amorphous．