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Fluorinated pyrazolinic thiosemicarbazones: selective synthesis and computational analysis Miranda, Victor Maia Machado, Vanessa Fernandes Marques, Fabio Luiz Navarro Deflon, Victor Marcelo 19F NMR Synthesis Pyrazoline ring Single-crystal structure Computational analysis Fluorinated thiosemicarbazone Thiosemicarbazones are a class of iminic organosulfur compounds synthesized by condensation reaction between a thiosemicarbazide and an aldehyde or ketone. Such compounds present a wide range of biological activities, either as sole organic compounds or in association with metallic species. The fluorinated pyrazoline cyclic thiosemicarbazones described herein were synthesized from 4,4,4-trifluoro-1-phenyl-1,3-butanedione and three thiosemicarbazides. The reactions resulted in thiosemicarbazones 1, 2, and 3, with 51, 70, and 71% yields, respectively. which were characterized by elemental analysis, FTIR, 1H and 19F{1H} NMR, mass spectrometry and single crystal X-ray diffraction. The spectral data confirm that the thiosemicarbazones are cyclic the both in solid state and solution, as no evidence of ring-chain tautomerism has been observed. Additionally, single-crystal X-ray diffraction studies revealed that the compounds mentioned above crystallized in centrosymmetric space groups, two of them in monoclinic P21/n and the last one in triclinic P . Theoretical free energies of formation were calculated using the DFT methodology, and the results indicate that the ring isomer is significantly more stable than the chain isomer; thus, no ring-chain isomerism is expected to form, in agreement with the experimental data. Atlanta Publishing House LLC 2025-12-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf application/pdf text/plain text/plain text/plain https://www.eurjchem.com/index.php/eurjchem/article/view/2663 10.5155/eurjchem.16.4.331-338.2663 European Journal of Chemistry; Vol. 16 No. 4 (2025): December 2025; 331-338 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/2663/2970 https://www.eurjchem.com/index.php/eurjchem/article/view/2663/2988 https://www.eurjchem.com/index.php/eurjchem/article/view/2663/2972 https://www.eurjchem.com/index.php/eurjchem/article/view/2663/2973 https://www.eurjchem.com/index.php/eurjchem/article/view/2663/2974 Copyright (c) 2025 Victor Maia Miranda, Vanessa Fernandes Machado, Fabio Luiz Navarro Marques, Victor Marcelo Deflon https://creativecommons.org/licenses/by-nc/4.0