Synthesis, Spectroscopic and Computational Studies of CT Complexes of Amino Acids with Iodine as σ Acceptor

Understanding the charge transfer process between bioactive molecules and inorganic or organic molecules is significant as this interaction can be used to interpret bioactive molecule-receptor interactions. A comprehensive spectrophotometric study has been performed to explore the complexation chemistry of the amino acids, tyrosine, lysine and arginine, with iodine as sigma acceptor. The molecular structure, spectroscopic characteristics and the interactive modes have been deduced from UV-Vis and IR spectra. The binding ratio of complexation has been determined to be 1:1 for iodine with the amino acids. The association constant (K), extinction coefficient (epsilon(max)), ionization potential (IP), energy of the charge transfer complex (E-CT), resonance energy (R (N) ), dissociation energy (W) and standard Gibbs energy (Delta GA degrees) have been computed. An in silico study has been carried out using GAMESS computations to understand the structural features. Highest occupied molecular orbital and lowest unoccupied molecular orbital calculations helped us in characterizing the chemical reactivity and kinetic stability of the molecules. A good consistency between experimental and computational results has been found.