Computational Studies for Oxidation Reduction Reactions of Cinnoline - 4(1H)-One, in Aqueous Phase by Density Functional Theory

The reduction and oxidation reactions of Cinnolin-4(1H)-one were studied in terms of reduction and oxidation potentials in aqueous phase. Geometry optimizations were performed at the 6-311++G (d, p) level by using the B3LYP functional theory. Cinnolin-4(1H)-one (I) has lower reduction potential (-0.184V) than that of of 2, 3-dihydrocinnolin-4(1H)-one (II) (-0.064 V). Oxidation potential of 2, 3-dihydrocinnolin-4(1H)-one (II), has greater negative value (-0.134V) than oxidation potential of 1, 2, 3, 4-tetrahydrocinnolin-4-ol (IV) (-0.091V). HOMO and LUMO energies are in increasing order: IV > II ≈ V > III > I and IV > II > V > I > III respectively, which is the same order as the strength of donating electrons in gas and aqueous phase. The values of µ, η, ω, and ∆Nmax show, compound (III) is good electrophile comparison of the other compounds in gas and aqueous phase. Therefore compound (III); the greater is the tendency of the oxidized form to get reduced by accepting electrons.