Tri-iodide charge-transfer complexes synthesized upon the chemical interaction between iodine and tryptophan or tyrosine
were characterized using different spectroscopic techniques (e.g., infrared, Raman, electronic, X-ray powder diffraction (XRD) and
scanning electron microscopy (SEM). The triiodide charge-transfer complexes were prepared by dry grinding of potassium iodide,
iodine and amino acid with 1:1:1 molar ratio in presence of few drops of

absorption bands around 360 and 280 nm due to the formation of the triiodide ion (I
3

). The Raman spectra show the characteristic
bands for the triiodide ion at 160, 126 and 100 cm
-1
, which are assigned to 
as
(I-I), 
s
(I-I) and  (I
3

), respectively. The iodine
complexes were shown to contain the triiodide species based on the electronic absorptions as well as on the Raman absorption bands
characteristic for the non-linear triiodide species, I
3

, with C
symmetry. The proposed structures of these complexes are further
supported by thermal analyses measurements. The DC electrical properties as a function of temperature of these charge transfer
complexes have been studied.