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•Pyrroles microwave irradiation synthesis and antioxidant assay.•Electronic device studies were performed.•Structure activity relationships and Interpretation.
A new series of pyrrole ...analogs were developed via the microwave irradiation synthesis. Consequently, got a high yield of the products. As pyrroles are familiar for showing various biological properties, all obtained compounds were screened for their antioxidant properties, most of the compounds showing significant activity. In fact, the motifs 5e, 5g, 5h and 5m showed outstanding antioxidant properties. Further, to enlighten the biologically energetic behavior underlying the antioxidant activity, compounds DFT studies were performed. Noteworthy results have been attained and the structure activity relationship (SAR) was discussed with the support of this results. It was found that highly biological active compounds exhibited a low HOMO-LUMO energy gap (Eg) and the high Eg value compounds show very low/negligible or inactive antioxidant activities. In other cases, compounds containing high HOMO energy levels also provide high antioxidant activity. The thought-provoking point of our results is that theoretical descriptors of the HOMO-LUMO energy gap and the highest occupied molecular orbital energy are important descriptors in the bioorganic research to support the biological experiments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The antibacterial activity of a calixarene derivative, p-tert-butylcalix6arene (Calix6), was assessed and was shown not to inhibit the growth of E. coli, S. aureus and B. subtilis bacteria. With the ...aim of gaining more insights into the absence of antibacterial activity of Calix6, the interaction of this derivative with DPPG, a bacterial cell membrane lipid, was studied. Langmuir monolayers were used as the model membrane. Pure DPPG and pure Calix6 monolayers, as well as binary DPPG:Calix6 mixtures were studied using surface pressure measurements, compressional modulus, Brewster angle and fluorescence microscopies, ellipsometry, polarization-modulation infrared reflection absorption spectroscopy and molecular dynamics simulations. Thermodynamic properties of the mixed monolayers were additionally calculated using thermodynamic parameters. The analysis of isotherms showed that Calix6 significantly affects the DPPG monolayers, modifying the isotherm profile and increasing the molecular area, in agreement with the molecular dynamics simulations. The presence of Calix6 in the mixed monolayers decreased the interfacial elasticity, indicating that calixarene disrupts the strong intermolecular interactions of DPPG hindering its organization into a compact arrangement. At low molar ratios of Calix6, the DPPG:Calix6 interactions are preferentially attractive, due to the interactions between the hydrophobic tails of DPPG and the tert-butyl groups of Calix6. Increasing the proportion of calixarene generates repulsive interactions. Calix6 significantly affects the hydrophobic tail organization, which was confirmed by PM-IRRAS measurements. Calix6 appears to be expelled from the mixed films at a biologically relevant surface pressure, π = 30 mN m-1, indicating a low interaction with the cell membrane model related to the absence of antibacterial activity.
In this paper, we employ the surface-specific polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation (SFG) methods with surface pressure and ...surface potential isotherms to determine the organization of p-tert-butylcalix6arene molecules and their interaction with Cd(2+) ions in Langmuir monolayers. The area per molecule was estimated to be 135 Å(2), which corresponds to the Calix6 axis perpendicular to the air-water interface with most OH groups parallel to the interface. This area is larger than predicted by molecular modeling with quantum chemical calculations with a PM3 Hamiltonian (109 Å(2)), which is ascribed to the repulsion between Calix6 molecules. The incorporation of Cd(2+) ions in the subphase leads to drastic changes in the dipole moment contribution of the monolayer surface potential. Rather than increasing with incorporation of Cd(2+) ions owing to a decrease in the negative double-layer potential, the measured surface potential decreased monotonically with increasing ion concentration. This unexpected result was ascribed to a strong interaction with Cd(2+) ions that induced the calyx of the molecule to adopt a more open conformation at the air/water interface and affected the orientation of hydration water molecules, according to the SFG data. This finding allows us to understand the reason why the Gouy-Chapman model fails to explain surface potential results for subphases containing divalent or trivalent ions, and may be relevant for the application of calixarenes in sensing.
Trisubstituted thiazoles were synthesized and studied for their antimicrobial activity and supported by theoretical calculations. In addition, MIC, MBC and MFC were also tested. Moreover, the present ...study was analyzed to scrutinize comprehensive structure-activity relationships. In fact, LUMO orbital energy and orbital orientation was reliable to explain their antibacterial and antifungal assay. Amongst the tested compounds, tri-methyl-substituted thiazole compound showed higher antimicrobial activity and low MIC value due to highest LUMO energy.
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•Synthesis and simulation studies.•HOMO-LUMO orbital orientation and calculated electronic parameters.•Correlation between biological assay with electronic parameters.•LUMO orbitals influenced the biological activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In the present study, by using green solvent and ecofriendly catalyst, a series of dihydropyridine and their analogs were synthesized. The total synthetic path proceeded under ecofriendly environment ...and a reusable heterogeneous catalyst was utilized, consequently, products formed with good yield. The prepared compounds examined using proton NMR, carbon NMR and mass spectroscopies studies. In addition, all final moieties were screened for their microbial resistance properties against four bacterial pathogens and two fungi. Most of the products demonstrated higher to moderate antimicrobial actions. Compounds 5e and 5n were noted the prominent microbial remedial behavior. Further, compounds electronic parameters such as HOMO energy, LUMO energy, their energy gap and other were calculated to investigate any structure activity relationships (SARs). There was some correlation existed between the simulations results and biological results. From SARs, the high LUMO energy value contained compound showed high antimicrobial property vice versa. Thus, the synthetic method in this research may judge as a model for further environmentally benign reactions and existed biological consequences stands for additional studies interrelated to biotic drugs. On the other hand, simulation results also an important descriptor to support the biological experiments.
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•Biologically active dihydropyridines and their environment friendly production.•Germ-free nature compounds, most of the compounds showed excellent antimicrobial action.•Machine results and their influences on bioactive compounds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, the aggregate formation of para-tert-butylcalix6arene molecules (Calix6) in dimeric structures was investigated at the water/air interface using experimental and theoretical studies. A ...specific orientation for such Calix6 molecules was observed with an average area of 133 Å(2), which corresponds to a flat-on orientation with the OH groups parallel to the interface. By varying the pressure on the Calix6 monolayer, the molecules tend to organize at the water/air interface and subsequently, at higher pressures, aggregates were formed atop the monolayer as cluster structures. Morphological characterization by the Brewster Angle Microscopy technique showed the formation of larger domains at lower pressures. Based on such experimental evidence, molecular dynamics (MD) simulations were performed to investigate possible dimeric structures for aggregated Calix6 molecules, which are localized at the water/air interface, where one molecule remains in the water phase and the other remains in the air phase. By increasing surface pressure, experimental and theoretical results corroborate the intermolecular interactions among Calix6 molecules. These results are relevant because a dimeric structure has a molecular cavity, which is a candidate for host-guest chemistry, an ion receptor or a drug-delivery system.
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In the present study, different extracts of stem bark of Shorea tumbuggaia and roots of Syzygium alternifolium were screened for total phenolic content (TPC), total flavonoid content ...(TFC) and in vitro DPPH radical scavenging activity to isolate the natural antioxidants. The bioassay-guided fraction of stem bark of Shorea tumbuggaia yielded three compounds, piceatannol (ST-1), resveratrol-12-C-β-d-glucopyranoside (ST-2) and hopeaphenol (ST-3). Similarly, a systematic phytochemical examination of extracts of Syzygium alternifolium roots had resulted five compounds, 5,7,8,5′-tetramethoxy-3′,4′-methylenedioxyflavone (SA-1), 5-hydroxy-4′,7-dimethoxy-6,8-di-C-methylflavone (SA-2), quercetin 7-methylether (SA-3), kaempferol 7,4′-dimethylether 3-O-β-d-glucopyranoside (SA-4) and taxifolin 3-O-α-l-rhamnopyranoside (SA-5). Structures of the isolates were established using UV, IR, Mass, 1H and 13C NMR spectral studies. Density Functional Theory (DFT) calculations, Molecular docking and Lipinski rule of five were conducted to explored the antioxidant activity of isolated compounds. SA-3 (37.52 µg/mL) and ST-1 (42.43 µg/mL) showed highest IC50 values compared to the Ascorbic acid (45.97 µg/mL) and have highest electron affinities (EA eV) along with smallest HOMO-LUMO energy gap. Molecular docking and binding affinity studies with NADPH and SPSB2 proteins, revealed the prominent antioxidant activity of SA-3 and ST-1 with molecular interaction besides promising solvation energies. Hence, the two compounds maybe useful for the treatment of oxidative damage related diseases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper investigates the geometrical, electronic, and optical properties of a Ga24N24H46 nanoparticle using Density Functional Theory (DFT). The results show that this nanoparticle maintains ...geometrical parameters very similar to those of the GaN crystal, although it was noticed that the bond length along the direction 0001 of the Ga24N24H46 nanoparticle is smaller than those of the base of the tetrahedron, which is the opposite of what occurs in the crystal. The bandgap of the passivated nanoparticle calculated with DFT is greater than that of the crystal, while an estimate for the hydrogen‐free Ga24N24 structure shows a much lower bandgap, in accordance with the literature. The simulation of the optical absorption spectra via Time‐Dependent DFT allowed the association of the spatial shape of electronic orbitals with particular transition energies. The highest occupied (HOMO) and lowest unoccupied (LUMO) electronic levels are located on the (0001) and (000‐1) surfaces of the particle, respectively, showing that the passivation of GaN nanoparticles should maintain its known photocatalytic activity, and that transition probability between those surface states is relatively low as compared to the HOMO‐4 and LUMO transitions at 4.16 eV. Results are compared with the available experimental data.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this paper, we employ the surface-specific polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation (SFG) methods with surface pressure and ...surface potential isotherms to determine the organization of
p-tert
-butylcalix6arene molecules and their interaction with Cd
2+
ions in Langmuir monolayers. The area per molecule was estimated to be 135 Å
2
, which corresponds to the
Calix6
axis perpendicular to the air-water interface with most OH groups parallel to the interface. This area is larger than predicted by molecular modeling with quantum chemical calculations with a PM3 Hamiltonian (109 Å
2
), which is ascribed to the repulsion between
Calix6
molecules. The incorporation of Cd
2+
ions in the subphase leads to drastic changes in the dipole moment contribution of the monolayer surface potential. Rather than increasing with incorporation of Cd
2+
ions owing to a decrease in the negative double-layer potential, the measured surface potential decreased monotonically with increasing ion concentration. This unexpected result was ascribed to a strong interaction with Cd
2+
ions that induced the calyx of the molecule to adopt a more open conformation at the air/water interface and affected the orientation of hydration water molecules, according to the SFG data. This finding allows us to understand the reason why the Gouy-Chapman model fails to explain surface potential results for subphases containing divalent or trivalent ions, and may be relevant for the application of calixarenes in sensing.
The SFG data show the orientation of
Calix6
molecules at the air/water interface, and their interaction with Cd ions.
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