Theoretical calculations of 1H NMR chemical shifts for nitrogenated compounds in chloroform solution

Silva, Haroldo C. Da; Almeida, Wagner B. De

doi:10.1016/j.chemphys.2019.110479

Cited by 42 publications

(35 citation statements)

References 27 publications

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“…Through the rise of reliable quantum chemical computational methods, such as Density Functional Theory (DFT), the DFT-NMR spectra of different organic compounds have been extensively reported. A comparison between the experimental and theoretical spectra in most cases reveals that they show the same profile [17][18][19]. Figures S1B and S2B show the theoretical DFT spectra ( 1 H-and 13 C-NMR) for the compound 7 and Table S1 compares the δ exp and δ calc values (experimental and theoretical, respectively).…”

Section: Organic Synthesis and Structure Determinationmentioning

confidence: 87%

2-Chloro-4,6-bis{(E)-3-methoxy-4-[(4-methoxybenzyl)oxy]styryl}pyrimidine: Synthesis, Spectroscopic and Computational Evaluation

Chaves

Sueth-Santiago

Pinto

et al. 2021

Molbank

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A novel curcumin analog namely 2-chloro-4,6-bis{(E)-3-methoxy-4-[(4-methoxybenzyl)oxy]-styryl}pyrimidine (compound 7) was synthesized by three-step reaction. The condensation reaction of protected vanillin with 2-chloro-4,6-dimethylpyrimidine (6) was the most efficient step, resulting in a total yield of 72%. The characterization of compound 7 was performed by 1H and 13C nuclear magnetic resonance (NMR), as well as high-resolution mass spectrometry. The experimental spectrometric data were compared with the theoretical spectra obtained by the density functional theory (DFT) method, showing a perfect match between them. UV-visible spectroscopy and steady-state fluorescence emission studies were performed for compound 7 in solvents of different polarities and the results were correlated with DFT calculations. Compound 7 showed a solvatochromism effect presenting higher molar extinction coefficient (log ε = 4.57) and fluorescence quantum yield (ϕ = 0.38) in toluene than in acetonitrile or methanol. The simulation of both frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP) suggested that the experimental spectra profile in toluene was not interfered by a possible charge transfer. These results are an indication of a low probability of compound 7 in reacting with unsaturated phospholipids in future applications as a fluorescent dye in biological systems.

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Section: Organic Synthesis and Structure Determinationmentioning

confidence: 87%

2-Chloro-4,6-bis{(E)-3-methoxy-4-[(4-methoxybenzyl)oxy]styryl}pyrimidine: Synthesis, Spectroscopic and Computational Evaluation

Chaves

Sueth-Santiago

Pinto

et al. 2021

Molbank

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“…The difficulty of the PCM model to fully reproduce the effect of solvent hydrogen bonding on chemical shift, as is the case CHCl 3 , has been emphasized by Benzi et al 35 In order to address this specific point a detailed theoretical analysis of various amine compounds, where experimental data in CHCl 3 solution is available, was carried out. 36 The results pointed out that N−H 1 H NMR chemical shifts are systematically underestimated at the DFT and ab initio post-Hartree Fock (HF) PCM-CHCl 3 level of theory, with the size of deviation being strongly dependent on the specific molecule investigated. It was found that the use of explicit solvent molecules in the NMR calculations improves considerably the agreement with experimental data in solution, however, such approach is not computationally viable for large and flexible molecules.…”

Section: Supramolecularity Through Hsmentioning

confidence: 99%

“…It can be seen that both rotated structures reproduce fairly well the NMR profile with the 5B'-rotated structure showing the best overall agreement for all protons (N−H, C−H aromatic, CH 2 and CH 3 ), being the best candidate as the observed molecular structure for compound I in chloroform solution. It should be said the theoretical N−H chemical shift must be seen as a qualitative value, 36 however, allowing analysis of the 1 H NMR pattern, which is the relevant information for structural analysis. A useful quantity to help examination of NMR spectrum is the difference between N−H signal and the largest C−H aromatic value, named here as Δ quote in Figure 9.…”

Section: Supramolecularity Through Hsmentioning

confidence: 99%

“…Keeping in mind the difficulty of theoretical methods using continuum model for the description of solvent effects to reproduce N−H 1 H NMR chemical shifts in solution and the fact that CH n protons NMR signals are adequately described at the DFT-PCM level, 36 we report MAE (mean absolute error) values for CH n protons of compounds I and II in Figure 12. It can be seen from Figure 12 that conformation 5B'-rotated exhibited the lowest MAE value for both compounds, and that conformation 2A'-rotated, which showed the best agreement with N−H protons, has a much higher MAE value.…”

Section: Supramolecularity Through Hsmentioning

confidence: 99%

See 1 more Smart Citation

Crystal Structure and 1H NMR Experimental and Theoretical Study of Conformers of 5-Methyl-1-(4’-methylphenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester and 5-Methyl-1-(phenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester

Freitas

Campos

Resende

et al. 2020

J. Braz. Chem. Soc.

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We reported experimental and theoretical investigation of conformers of 1,2,3-triazole derivatives, substances of exclusively synthetic origin, subject of extensive studies, because of several biological properties, such as antiviral, antimicrobial and antileishmaniasis. We reported molecular/supramolecular X-ray structures of antiophidian compounds I and II. For I and II there are two crystallographic different molecules in the unit cell (A and B). To explore the causes of the similarities in the compound's crystal structures, intermolecular interactions were explored using the Hirshfeld surface as the fingerprint plots. In addition, density functional theory (DFT) calculations were carried out at the ωB97x-D/6-31G(d,p)-PCM-CHCl 3 level aiming to contribute to the interpretation of the experimental data and complement the experimental findings. Two structures named 2A and 5B were found in good agreement with the respective X-ray solid state ones (A and B). Theoretical 1 H nuclear magnetic resonance (NMR) spectra calculated for 5B rotated structure (torsion angles deviation around 40° to 90°) was in fine agreement with experimental results (in CDCl 3) indicating that the solution molecular structure is considerably different from optimized equilibrium geometries and solid-state structure. Therefore, care is needed when using X-ray structures or DFT geometries to model interaction of drugs with biological targets since significant conformational changes may take place in solution.

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“…1 H and 13 C NMR of the investigated compounds were estimated experimentally in DMSO solvent and TMS as an internal standard. We calculated 1 H and 13 C NMR in similar media (DMSO) using GIAO method at the same level of optimization [25][26][27][28][29][30]. As seen in Table 3 and supplementary data, shielding of carbon joined to substitute in R 4 position is higher than R 2 position in all compounds.…”

Section: Nmr Analysismentioning

confidence: 99%

Theoretical and experimental investigations into the structural, electronic, and molecular properties of 1,5-dihydropyrano[2,3-c]chromene derivatives

2019

Biointerface Res Appl Chem

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In this study, a simple and efficient method for the synthesis of 1,5-dihydropyrano[2,3-c]chromene derivatives is reported by three component reaction of aromatic aldehydes, malononitrile, and 3-hydroxycoumarin in the presence of piperidine as base in ethanol, under reflux conditions. Also, the experimental results involving new and already synthesized compounds are compared with the theoretical calculations. The energy, molecular electrostatic potential (MEP), HOMO–LUMO energy gap, chemical properties and NMR analyses of 1,5-dihydropyrano[2,3-c]chromene derivatives in DMSO solution were estimated using density functional theory and 6-311++G (d,p) basis set. The solvent effect was explored using the polarizable continuum model (PCM) method. Increasing polarity and having no much difference in energies show the more effects of newly synthesized compounds (R2-DHPC) towards already synthesized compounds (R4-DHPC) in human body. Also, the results display that there is a good agreement between experimental and theoretical data.

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Theoretical calculations of 1H NMR chemical shifts for nitrogenated compounds in chloroform solution

Cited by 42 publications

References 27 publications

2-Chloro-4,6-bis{(E)-3-methoxy-4-[(4-methoxybenzyl)oxy]styryl}pyrimidine: Synthesis, Spectroscopic and Computational Evaluation

2-Chloro-4,6-bis{(E)-3-methoxy-4-[(4-methoxybenzyl)oxy]styryl}pyrimidine: Synthesis, Spectroscopic and Computational Evaluation

Crystal Structure and 1H NMR Experimental and Theoretical Study of Conformers of 5-Methyl-1-(4’-methylphenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester and 5-Methyl-1-(phenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester

Theoretical and experimental investigations into the structural, electronic, and molecular properties of 1,5-dihydropyrano[2,3-c]chromene derivatives

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