Conformational stability, spectral analysis (infrared, Raman and NMR) and DFT calculations of 2-Amino-5-(ethylthio)-1,3,4-thiadiazole

Mohamed, Tarek A.; Hassan, Ahmed E.; Shaaban, Ibrahim A.; Abuelela, Ahmed M.; Zoghaib, Wajdi M.

doi:10.1016/j.molstruc.2016.10.002

Cited by 13 publications

(4 citation statements)

References 41 publications

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“…From the theoretical point of view, there are many studies of conformational stability using ab initio calculations with quantum mechanics (QM) in vacuum and in solution with the solvent effect described by the polarizable continuum model (PCM) or solvent‐clusters . However, another well‐known approach to describe the solvent and its interactions with solute molecules is using computer simulations with Monte Carlo (MC) or molecular dynamics (MD) methods .…”

Section: Introductionmentioning

confidence: 99%

Solvent effect on the syn/anti conformational stability: A comparison between conformational bias Monte Carlo and molecular dynamics methods

Cezar

Canuto

Coutinho

2018

Int J of Quantum Chemistry

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The solvent effect on the syn/anti population ratio of the mesityl oxide (MOx) was investigated using a new implementation of conformational bias Monte Carlo (CBMC) and molecular dynamics (MD) methods. It was observed by a previous theoretical work (Theor. Chem. Acc. (2012) 131:1214) that in gas-phase the MOx exists dominantly in syn-form and in aqueous solution in anti-form. The syn/anti free energy difference in the gas phase was used in the intramolecular parametrization and a rotational barrier of approximately 10 kcal mol −1 was found. Molecular systems with barriers of this order of magnitude have been studied by experimental techniques. However, they have not been discussed yet comparing CBMC and MD simulations. In this work, we show that the intramolecular geometrical information such as bond lengths, angles and torsional angles sampled with CBMC and MD methods are equivalent. Nonetheless, only the CBMC simulations sample appropriately the syn/anti population ratio. With the CBMC configurations in gas phase, it was obtained 95% in syn-form and 5% in anti-form regardless the initial conformation. An inversion of the population was found in water, 25% in syn-form and 75% in anti-form. Comparing the gas phase and in-water CBMC sampling, it was observed that the MOx spends typically approximately 110 successive MC cycles in anti-form and approximately 2300 in syn-form in gas phase. While it was much larger with explicit water, approximately 400 times more for anti-form and approximately 6 times more for syn-form. We argue that this strong stabilization of the anti-form in aqueous solution, does not come from the MOx-water hydrogen bonds interactions, because they are the same for both conformations. Instead, the stabilization comes from the dipole-dipole interaction caused by a larger dipole moment of the MOx in the anti-form, 7.2 D, than in the syn-form, 5.2 D. With the MD sampled configurations in both conditions, we observe that the syn/anti conformational change is a very rare event due to the rotational barrier, which is approximately 17 times larger than the thermal energy. Therefore, the MD sampling of the MOx is not appropriated because it is strongly dependent on the initial conformation even for large simulations with 150 ns up to 400 ns for the isolated solute and for solute-solvent systems.

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Section: Introductionmentioning

confidence: 99%

Solvent effect on the syn/anti conformational stability: A comparison between conformational bias Monte Carlo and molecular dynamics methods

Cezar

Canuto

Coutinho

2018

Int J of Quantum Chemistry

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“…18 [56]. Additional bands together with slight Raman shifts are observed for the complex compared to the free ligand in this region.…”

Section: Raman Spectroscopymentioning

confidence: 88%

Cobalt(II) coordination complex with 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole and thiocyanate as co-ligand: Synthesis, crystal structure, Hirshfeld surface analysis, spectroscopic, thermal and magnetic properties

Laachir

Rhoufal

Guesmi

et al. 2020

Journal of Molecular Structure

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Cobalt(II) coordination complex with 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole and thiocyanate as co-ligand: Synthesis, crystal structure, Hirshfeld surface analysis, spectroscopic, thermal and magnetic properties

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“…The medium stretching band observed at 1523 cm À1 describes the endocyclic C]N group of the thiadiazol ring. 41 In addition, the C]C stretching vibrations occur in the region 1430-1625 cm À1 . 42 In our work, this peak occurs in the range of 1482-1523 cm À1 and is calculated at 1495-1500 cm À1 .…”

Section: Vibrational Spectral Analysis (Ir Spectra)mentioning

confidence: 99%

Solvent polarity tuning to enhance the crystallinity of 2D-covalent organic frameworks for visible-light-driven hydrogen generation

et al. 2022

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Conformational stability, spectral analysis (infrared, Raman and NMR) and DFT calculations of 2-Amino-5-(ethylthio)-1,3,4-thiadiazole

Cited by 13 publications

References 41 publications

Solvent effect on the syn/anti conformational stability: A comparison between conformational bias Monte Carlo and molecular dynamics methods

Solvent effect on the syn/anti conformational stability: A comparison between conformational bias Monte Carlo and molecular dynamics methods

Cobalt(II) coordination complex with 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole and thiocyanate as co-ligand: Synthesis, crystal structure, Hirshfeld surface analysis, spectroscopic, thermal and magnetic properties

Solvent polarity tuning to enhance the crystallinity of 2D-covalent organic frameworks for visible-light-driven hydrogen generation

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