The interaction of iodine as a sigma-acceptor with two derivatives of polyamidoamine dendrimers (donor), 1,8-naphthalimide polyamidoamine (PAM1) and 4-piperidino-1,8-naphthalimide polyamidoamine (PAM2) have been investigated spectrophotometrically at room temperature in chloroform. The results indicate the formation of two CT-complexes [(PAM1)I](+)I(3)(-) and [(PAM2)(2)I](+)I(3)(-) with molar ratios of 1:2 and 1:1, respectively. The formation of these two complexes are in good agreement with their elemental analysis, infrared measurements and photometric titration plots based on the characteristic absorption bands of I(3)(-) ion around 280 and 360 nm. Moreover the formation of triiodide ion, I(3)(-), in both of the two complexes was supported by measuring their spectra in the far-infrared region. Three characteristic bands are observed at 125, 110 and 75 cm(-1) due to nu(as)(I-I), nu(s)(I-I) and delta(I(3)(-)), respectively, with C(2v) symmetry.