UV spectral features of poly(propylene imine) dendrimers

Abstract

The UV optical spectra of amine terminated poly(propylene-imine) (PPI) dendrimers of generatons G1 to G5 were investigated experimentally. The occurrence of double band at (270–290) nm in absorption spectra of amine terminated dendrimer and the dependence of the spectra on the generation number and concentration in dichloromethane solution were discussed. The lineshape of double band was similar in the sequence G1 to G5, though some redistribution of the intensity of components was observed. A linear dependence of the absorbance in the double band was determined in the solutions at low concentrations of order 1x10–5 M. Experimental data have indicated that double band is caused by several optical transitions related to the core electronic excitations. A significant Rayleigh light scattering was found for higher dendrimer generations. Keywords: PPI NH2-terminated dendrimers, optical absorbance, light scattering