Unveiling geometrical isomers and tautomers of isatin-hydrazones by NMR spectroscopy

Wegermann, Camila Anchau; Monzani, Enrico; Casella, Luigi; Ribeiro, Marcos A.; Bruzeguini, Carlos E.T.; Vilcachagua, Janaína D.; Costa, Luiz Antônio S.; Ferreira, Ana Maria da Costa

doi:10.1016/j.molstruc.2021.131633

Cited by 7 publications

(5 citation statements)

References 49 publications

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“…Bands at 262 and 385 nm are assigned to →* transitions of the phenyl ring of the dithiocarbazate and isatin moieties, while band at 449 nm is attributed to n→* transition of the carbonylic, thione and azomethine chromophores, respectively. Similar intraligand transitions were also observed in a related structure containing isatin analogues [40,41]. The appearance of a S→Ni(II) ligand to metal charge transfer (LMCT) transition in the spectrum of Ni(SBISA)2 at 474 nm suggests a strong evidence that the dithiocarbazate sulfur atom is involved in the coordination.…”

Section: Compoundsupporting

confidence: 64%

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

Manan

Mohammat²

2022

Trends Sci

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A tridentate nitrogen-oxygen-sulfur (NOS) S-benzyl(2-oxoindolin-3-ylidene)dithiocarbazate, HSBISA (HL1) ligand was synthesized via a condensation reaction between S-benzylditihocarbazate (SBDTC) and isatin. The produced ligand was reacted with nickel(II) acetate salt in 1:2 (metal:ligand) ratio to yield a brown Ni(SBISA)2 complex (2) (SBISA = monoanionic form of HL1). Characterization of HL1 and its Ni(II) complex was performed via elemental analysis, FT-IR, ICP-AES, UV-Vis spectroscopy and mass spectrometry, along with molar conductivity and magnetic susceptibility measurement. Slow evaporation of 2 from DMSO at room temperature led to a structure crystallizing in the monoclinic P21/a space group with a = 18.6860(3), b = 11.3037(2), c = 19.8993(3), b = 112.1897(10), V = 3891.86(11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I). The nickel(II) metal center is ligated by doubly-deprotonated NOS monoanionic tridentate HL1 ligands forming a neural distorted octahedral Ni(SBISA)2×2DMSO (2a) complex. The antimicrobial assays of both compounds were performed on selected pathogenic bacteria and fungi strains. HIGHLIGHTS Octahedral Ni(II) complex was synthesized using acetate salt Compound was characterized via physico-chemical analyses Structural studies were resolved via single crystal X-ray diffraction Compound 2a crystallized in a monoclinic system (P21/a space group) with cell parameters a = 18.6860 (3), b = 11.3037 (2), c = 19.8993(3), b = 112.1897 (10), V = 3891.86 (11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I) Compound was evaluated for its antimicrobial activity GRAPHICAL ABSTRACT

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Section: Compoundsupporting

confidence: 64%

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

Manan

Mohammat²

2022

Trends Sci

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“…However, they interconvert rapidly in solution at room temperature and cannot be separated. Generally, the ratios of such indolinone hydrazone isomers are solvent- and temperature-dependent, as previously reported [ 66 , 67 , 68 ]. Thus, these isomers are not separable.…”

Section: Resultssupporting

confidence: 63%

1-Benzyl-5-bromo-3-hydrazonoindolin-2-ones as Novel Anticancer Agents: Synthesis, Biological Evaluation and Molecular Modeling Insights

et al. 2023

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Human health is experiencing several obstacles in the modern medical era, particularly cancer. As a result, the cancer therapeutic arsenal should be continually expanded with innovative small molecules that preferentially target tumour cells. In this study, we describe the development of two small molecule series (7a–d and 12a–e) based on the 1-benzyl-5-bromoindolin-2-one scaffold that connected through a hydrazone linker to a 4-arylthiazole (7a–d) or 4-methyl-5-(aryldiazenyl)thiazole (12a–e) moiety. The anticancer activity of all the reported indolin-2-one derivatives was assessed against breast (MCF-7) and lung (A-549) cancer cell lines. The 4-arylthiazole-bearing derivatives 7c and 7d revealed the best anticancer activity toward MCF-7 cells (IC50 = 7.17 ± 0.94 and 2.93 ± 0.47, respectively). Furthermore, the VEGFR-2 inhibitory activity for 7c and 7d was evaluated. Both molecules disclosed good inhibitory activity, and their IC50 values were equal to 0.728 µM and 0.503 µM, respectively. Additionally, the impacts of 7d on the cell cycle phases as well as on the levels of different apoptotic markers (caspase-3, caspase-9, Bax, and Bcl-2) were assessed. Molecular docking and dynamic simulations are carried out to explore the binding mode of 7d within the VEGFR-2 active site.

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“…Studies of the influence of analogous hydrazones derived from oxindoles in the aggregation inhibition of β−amyloid peptides, enhanced in the presence of metal ions such as copper, zinc, or iron, indicated the possibility of six isomers, detected by NMR spectroscopy among the E-and Z-forms, and corresponding ketoenol tautomers (Wegermann et al, 2022). DFT simulations supported the experimental results, attesting that the most stable isomers in solution are the keto isomers in corresponding Z-forms.…”

Section: Strategies To Favor the Most Active Tautomeric Speciesmentioning

confidence: 64%

Keto-enol tautomerism in the development of new drugs

Araujo de Oliveira,

Wegermann,

Ferreira

2024

Front. Chem. Biol.

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The presence of isomers is a huge challenge in the development of new medicinal or pharmaceutical agents because the main goal is to obtain the most active compound with high purity and yield. Tautomerism is a phenomenon quite common in biomolecules that also appears in many drugs, and strategies to control the corresponding desired species and related equilibrium conditions leading to efficient chemical speciation are frequently required. There are many reports in the literature about the presence of tautomers, although some articles do not properly emphasize their occurrence or their importance for the differences verified in biological activity. Herein, a discussion about tautomers observed in both metalated and non-metalated compounds and their importance in the biological properties of promising drugs is revisited. Mainly, keto-enol equilibria among imines, hydrazones, and oxindole derivatives are showcased, based on significant examples, and strategies to improve their speciation or to better elucidate their modes of action are suggested.

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Unveiling geometrical isomers and tautomers of isatin-hydrazones by NMR spectroscopy

Cited by 7 publications

References 49 publications

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

1-Benzyl-5-bromo-3-hydrazonoindolin-2-ones as Novel Anticancer Agents: Synthesis, Biological Evaluation and Molecular Modeling Insights

Keto-enol tautomerism in the development of new drugs

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