Complexation of anthracene with folic acid studied by FTIR and UV spectroscopies

Toxicity and transformation process of polycyclic aromatic hydrocarbons (PAHs) is strongly depended on the interaction between PAHs and the coexisting compounds. Complexation between folic acid (FA) and a typical PAH, anthracene, was investigated using FTIR and UV spectra. Appearance of a new IR band at 2362 cm−1 demonstrates that NH2–CN(1)– moiety on pterin (PT) ring in FA is protonated when anthracene is introduced. The shift of the characteristic IR band of the PT ring and the emergence of two charge transfer bands at 254 nm and 246 nm in UV difference spectra show the presence of π–π complexation between folic acid and anthracene. These experiments confirm that anthracene could combine with the pterin ring of folic acid through π–π donor–acceptor interaction (EDA) and induce the protonation process in FA upon strengthening electron accepting ability of PT ring.