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

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 p-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 -> pi* transition (FP -> acceptor) into stable, colored products. Physical parameters such as the molar extinction coefficient (epsilon(max)), formation constant (K-CT), 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. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the charge-transfer chemistry of pyrazole derivative FP with five p-acceptors, demonstrating the formation of stable CT complexes through an n -> pi* transition. Strong statistically significant correlations were found between various spectroscopic parameters.