Protonation/deprotonation process of Emodin in aqueous solution and 'pK IND. a' determination: UV/Visible spectrophotometric titration and quantum/molecular mechanics calculations - Cunha, Antonio Rodrigues da; Duarte, Evandro Luiz; Lamy, Maria Teresa Moura; Coutinho, Kaline Rabelo (CHEMICAL PHYSICS, 2014)