Computational Study on 4-Amino-3-Hydroxynaphthalene-1-Sulfonic Acid (AHNSA)

A computational study on 4-amino-3-hydroxynaphthalene-1-sulfonic acid (AHNSA) has been carried out to investigate formation of poly-(AHNSA), and to obtain binding structures and energies of AHNSA-Ephedrine and AHNSA-Caffeine complexes. For this purpose, the DFT/B3LYP/6-31G(D) and DFT/B3LYP/6-31+G(D) level of theories were utilized. These were investigated from analysis of their atomic charge distributions, total spin density, frontier molecular orbitals, electrostatic potential maps and calculations of binding energies. Results from analysis suggest that homo-polymerization of AHNSA should involve the molecular orbitals arising between radical cations formed from the neutral monomer. The resulting data illustrated that the method was likely to be useful for homo-polymerization of AHNSA. Calculated binding energies of AHNSA-Caffeine and AHNSA-Ephedrine complexes were -8.77 kcal mol-1 and -8.36 kcal mol-1, respectively, which indicated that both complexes could be formed.