title: Synthesis, spectroscopic and computational characterization of the tautomerism of pyrazoline derivatives from chalcones.
abstract: In the present study a series of novel pyrazolines derivatives has been synthesized, and their structures assigned on the basis of FT-Raman, (1)H and (13)C NMR spectral data and computational DFT calculations. A joint computational study using B3LYP/6-311G(2d,2p) density functional theory and FT-Raman investigation on the tautomerism of 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carbothioamide and 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carboxamide are presented. The structures were characterized as a minimum in the potential energy surface using DFT. The calculated Raman and NMR spectra were of such remarkable agreement to the experimental results that the equilibrium between tautomeric forms has been discussed in detail. Our study suggests the existence of tautomers, the carboxamide/carbothioamide group may tautomerize, in the solid state or in solution. Thermodynamic data calculated suggests that the R(CS)NH2 and R(CO)NH2 species are more stable than the R(CNH)SH and R(CNH)OH species. Additionally, results found for the (1)H NMR shifting, pointed out to which structure is present.
authors.affiliation: NUPEQ - Núcleo Multifuncional de Pesquisas Químicas, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Fábio Balbino
authors.initials: FB
authors.lastname: Miguel
authors.affiliation: NUPEQ - Núcleo Multifuncional de Pesquisas Químicas, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Juliana Arantes
authors.initials: JA
authors.lastname: Dantas
authors.affiliation: NEEM - Laboratório de Nanoestruturas Plasmônicas, Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Stefany
authors.initials: S
authors.lastname: Amorim
authors.affiliation: NEEM - Laboratório de Nanoestruturas Plasmônicas, Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Gustavo F S
authors.initials: GF
authors.lastname: Andrade
authors.affiliation: NEQC - Núcleo de Estudos em Química Computacional, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Luiz Antônio Sodré
authors.initials: LA
authors.lastname: Costa
authors.affiliation: NUPEQ - Núcleo Multifuncional de Pesquisas Químicas, Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-900 Juiz de Fora, MG, Brazil. Electronic address: mara.rubia@ufjf.edu.br.
authors.forename: Mara Rubia Costa
authors.initials: MR
authors.lastname: Couri
mesh_terms: D047188:Chalcones / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman
chemical_list: D047188:Chalcones; D011720:Pyrazoles
keywords: Chalcones; DFT; Pyrazolines; Raman; Synthesis; Tautomerism