<sup>13</sup>C CP‐MAS study of the polymorphs of naphthazarin and of some methyl derivatives

Olivieri, Alejandro C.; Paul, Iain C.; Curtin, David Y.

doi:10.1002/mrc.1260280206

Cited by 27 publications

(16 citation statements)

References 26 publications

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“…IR (cm −1 ): 2962 (ν C-H ), 1594 (ν C O ), 1404, 1594 (ν C CAr ), and 1214 (ν C-O ). Doubling of some signals on 13 C NMR was reported for this molecule and can be explained by the presence of polymorphs as described by Olivieri et al (1990). 1 H NMR (300 MHz, chloroform-d) δ 0.70 (t, J 7.…”

Section: 8-dihydroxysupporting

confidence: 55%

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Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

et al. 2021

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Infections caused by drug-resistant bacteria are a serious threat to human and global public health. Moreover, in recent years, very few antibiotics have been discovered and developed by pharmaceutical companies. Therefore, there is an urgent need to discover and develop new antibacterial agents to combat multidrug-resistant bacteria. In this study, two novel series of juglone/naphthazarin derivatives (43 compounds) were synthesized and evaluated for their antibacterial properties against various clinical and reference Gram-positive MSSA, clinical Gram-positive MRSA, and clinical and reference Gram-negative bacteria E. coli and P. aeruginosa. These strains are of clinical importance because they belong to ESKAPE pathogens. Compounds 3al, 5ag, and 3bg showed promising activity against clinical and reference MSSA (MIC: 1–8 µg/ml) and good efficacy against clinical MRSA (MIC: 2–8 µg/ml) strains. 5am and 3bm demonstrated better activity on both MSSA (MIC: 0.5 µg/ml) and MRSA (MIC: 2 µg/ml) strains. Their MICs were similar to those of cloxacillin against clinical MRSA strains. The synergistic effects of active compounds 3al, 5ag, 5am, 3bg, and 3bm were evaluated with reference antibiotics, and it was found that the antibiotic combination with 3bm efficiently enhanced the antimicrobial activity. Compound 3bm was found to restore the sensitivity of clinical MRSA to cloxacillin and enhanced the antibacterial activity of vancomycin when they were added together. In the presence of 3bm, the MIC values of vancomycin and cloxacillin were lowered up to 1/16th of the original MIC with an FIC index of 0.313. Moreover, compounds 3al, 5ag, 5am, 3bg, and 3bm did not present hemolytic activity on sheep red blood cells. In silico prediction of ADME profile parameter results for 3bm is promising and encouraging for further development.

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Section: 8-dihydroxysupporting

confidence: 55%

“…13 C NMR (75 MHz, ). Doubling of some signals on 13 C NMR was reported for this molecule and can be explained by the presence of polymorphs as described by Olivieri et al (1990). 1 H NMR (300 MHz, chloroform-d) δ 0.97 (s, 18H, 6CH 3 ), 2.58 (s, 4H, 2CH 2 ), 6.92 (s, 2H, 2CH Ar ), 12.55 (s, 1H, OH), and 13.27 (s, 1H, OH).…”

Section: 8-dihydroxymentioning

confidence: 53%

Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

et al. 2021

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“…Further comparisons of polymorphs A, B and C showed that the O-H...O intermolecular hydrogen bond was detected in the latter structure. The crystallographic analysis combined with available solid state NMR data provided information that at room temperature there is a rapid intramolecular proton exchange in the hydrogen bridge in all three Naphthazarin polymorphs [ 23 , 24 , 25 , 26 ]. The IR and Raman spectra were recorded for Naphthazarin confirming the presence of the intramolecular hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

Non-Covalent Forces in Naphthazarin—Cooperativity or Competition in the Light of Theoretical Approaches

Jezierska

Błaziak

Klahm

et al. 2021

IJMS

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Non-covalent interactions responsible for molecular features and self-assembly in Naphthazarin C polymorph were investigated on the basis of diverse theoretical approaches: Density Functional Theory (DFT), Diffusion Quantum Monte Carlo (DQMC), Symmetry-Adapted Perturbation Theory (SAPT) and Car-Parrinello Molecular Dynamics (CPMD). The proton reaction paths in the intramolecular hydrogen bridges were studied. Two potential energy minima were found indicating that the proton transfer phenomena occur in the electronic ground state. Diffusion Quantum Monte Carlo (DQMC) and other levels of theory including Coupled Cluster (CC) employment enabled an accurate inspection of Potential Energy Surface (PES) and revealed the energy barrier for the proton transfer. The structure and reactivity evolution associated with the proton transfer were investigated using Harmonic Oscillator Model of Aromaticity - HOMA index, Fukui functions and Atoms In Molecules (AIM) theory. The energy partitioning in the studied dimers was carried out based on Symmetry-Adapted Perturbation Theory (SAPT) indicating that dispersive forces are dominant in the structure stabilization. The CPMD simulations were performed at 60 K and 300 K in vacuo and in the crystalline phase. The temperature influence on the bridged protons dynamics was studied and showed that the proton transfer phenomena were not observed at 60 K, but the frequent events were noticed at 300 K in both studied phases. The spectroscopic signatures derived from the CPMD were computed using Fourier transformation of autocorrelation function of atomic velocity for the whole molecule and bridged protons. The computed gas-phase IR spectra showed two regions with OH absorption that covers frequencies from 2500 cm−1 to 2800 cm−1 at 60 K and from 2350 cm−1 to 3250 cm−1 at 300 K for both bridged protons. In comparison, the solid state computed IR spectra revealed the environmental influence on the vibrational features. For each of them absorption regions were found between 2700–3100 cm−1 and 2400–2850 cm−1 at 60 K and 2300–3300 cm−1 and 2300–3200 cm−1 at 300 K respectively. Therefore, the CPMD study results indicated that there is a cooperation of intramolecular hydrogen bonds in Naphthazarin molecule.

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“…The change in the anisotropy values is controlled by relative differences among individual π P᎐O bond orders. 32 Hence, the described increase of ∆σ accompanies the increase of π electron density along the involved bond produced by a smaller contribution of the (TMPPO-H) ϩ structure with weaker proton donors. Thus, this effect should be the result of a smaller degree of hydrogen transfer when the substituted phenol increases its pK a value.…”

Section: Solid-state Studiesmentioning

confidence: 94%

NMR studies of proton transfer in 1∶1 tris(trimethoxyphenyl)phosphine oxide–phenol complexes

Lagier¹,

Olivieri²,

Harris³

1998

J. Chem. Soc., Perkin Trans. 2

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¹³C CP‐MAS study of the polymorphs of naphthazarin and of some methyl derivatives

Cited by 27 publications

References 26 publications

Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

Non-Covalent Forces in Naphthazarin—Cooperativity or Competition in the Light of Theoretical Approaches

NMR studies of proton transfer in 1∶1 tris(trimethoxyphenyl)phosphine oxide–phenol complexes

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13C CP‐MAS study of the polymorphs of naphthazarin and of some methyl derivatives

Cited by 27 publications

References 26 publications

Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

Synthesis, Structure Elucidation, Antibacterial Activities, and Synergistic Effects of Novel Juglone and Naphthazarin Derivatives Against Clinical Methicillin-Resistant Staphylococcus aureus Strains

Non-Covalent Forces in Naphthazarin—Cooperativity or Competition in the Light of Theoretical Approaches

NMR studies of proton transfer in 1∶1 tris(trimethoxyphenyl)phosphine oxide–phenol complexes

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Product

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¹³C CP‐MAS study of the polymorphs of naphthazarin and of some methyl derivatives