Chemical and physical investigations on the charge transfer interaction of organic donors with iodine and its application as non-traditional organic conductors

•The iso-leucine-iodide and methionine-iodide charge-transfer complexes were prepared and characterized.•The structures of iodide charge-transfer complexes are discussed with Raman laser spectra.•The electrical properties of both complexes were investigated.•The positron annihilation Doppler broadening spectroscopes were performed.

The iso-leucine-iodide and methionine-iodide charge-transfer complexes were prepared and characterized using different spectroscopic techniques. The iodide charge-transfer complexes were synthesized by grinding KI-I2-amino acid with 1:1:1 M ratio in presence of few drops of methanol solvent. The structures of both solid amino acid iodide charge-transfer complexes are discussed with the help of the obtained results of the infrared and Raman laser spectra, Uv–vis. electronic spectra and thermal analyses. The electrical properties (AC resistivity and dielectric constant) of both complexes were investigated. The positron annihilation Doppler broadening (PADB) spectroscopies were also used to probe the structural changes of both complexes. The PADB line-shape parameters (S and W) were found to be dependent on the structure, electronic configuration of the charge transfer complex. The PADB technique is a powerful tool to probe the structural features of the KI-I2-amino acid complexes.