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 flight (MALDI-TOF) mass 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.
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