Synthesis and Characterization of Fluorescent Poly(aromatic amide)Dendrimers

摘要

The synthesis of a series of poly(aromatic amide)dendrimers up to the second generation is described herein.The AB_2 building block used throughout the synthesis of the dendrimers was the allyl ester of 3,5-diaminocinnamic acid,which has been synthesized from 3,5-dinitrobenzoic acid in good yield with use of a four-step procedure.Dendron synthesis was achieved via a convergent approach with use of a sequence of deprotection/coupling steps.Two commercially available alcohols,L-menthol and citronellol,were coupled to the AB_2 monomer by using an alkyl diacid spacer and two core units;1,7-diaminoheptane and tris(2-aminoethyl)amine have been used to produce the final dendrimers.Characterization was carried out by NMR and IR spectroscopies,MALDI-TOF mass spectrometry,GPC,and DSC.The novel monomer and dendritic derivatives exhibited a strong fluorescence emission in the visible region(lambda approx= 500 nm)of the spectrum and a weak emission in the near-infrared(lambda approx=850 nm)upon excitation in the near-UV region.The fluorescence emission characteristics were found to be solvent and dendrimer generation dependent.