Exploring the charge-transfer chemistry of fluorine-containing pyrazolin-5-ones: The complexation of 1-methyl-3-trifluoromethyl-2-pyrazoline-5-one with five π-acceptors

Abstract

Pyrazole derivatives play an important role in medicinal chemistry. In this study, we investigated the charge-transfer (CT) chemistry of one of these derivatives, 1-methyl-3-trifluoromethyl-2-pyrazoline-5-one, referred to as FP. This target compound was interacted with five π-acceptors; picric acid, chloranilic acid, fluoranil, DDQ, and TCNQ in methanol. The elemental and spectral results indicate that the synthesized CT complexes formed with 1:1 FP to acceptor stoichiometry in an exothermic, spontaneous reaction via an n → π* transition (FP → acceptor) into stable, colored products. Physical parameters such as the molar extinction coefficient (εmax), formation constant (KCT), and other spectroscopic data were calculated using the 1:1 Benesi-Hildebrand method. Pearson's correlation coefficient analysis revealed strong statistically significant correlations between several of the spectroscopic parameters.