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1.
An analysis of the results of the fluorescence spectrum investigation of all-trans-deca-1,3,5,7,9-pentaene and t,C,t,T,t,T,t-deca-1,3,5,7,9-pentaene in an n-decane matrix [B.E. Kohler, V. Terpougov, J. Chem. Phys. 108 (1998) 9586–9593] has been performed using scaled quantum mechanical force field (SQM-FF) methodology at the HF/6-31G level. The measured vibronic wavenumbers were assigned taking into account the results of quantum-chemical predictions of the vibrational spectra for all-trans-deca-1,3,5,7,9-pentaene and t,C,t,T,t,T,t-deca-1,3,5,7,9-pentaene. Results from additional calculations at the MP2(FC)/aug-cc-pVDZ and B3LYP/6-311++G(d,p) levels are also reported.  相似文献   

2.
The title compounds were synthesized and characterized by structural measurements and electronic structure calculations. Single-crystal X-ray diffraction analyses established that they all have the orthorhombic inverse-PbCl2-type structure (Pnma, Z=4, a=8.108(2), 8.124(2), 8.421(2), 8.509(2) Å; b=4.944(1), 4.949(1), 5.168(1), 5.189(1) Å; c=9.170(2), 9.184(2), 9.685(2), 9.740(2) Å, respectively). The tetrel (Tt) atoms are situated in tricapped trigonal prisms of ordered Sr and Ca atoms in which the smaller Ca atoms play a distinctive role. The structure is distinguishable from the Co2Si type by its more nearly ideal 6+3 (TCTP) environment about Tt rather than a higher coordination by cations. Other representations of the two structural types are also considered. Electronic band structure calculations suggest that the compounds are semiconductors, in agreement with literature data on their Ae2Tt analogues.  相似文献   

3.
《Tetrahedron: Asymmetry》2007,18(21):2510-2513
The highly diastereoselective conjugate addition of lithium (S)-N-benzyl-N-(α-methylbenzyl)amide to a γ-silyloxy-α,β-unsaturated ester and in situ enolate oxidation with (+)-(camphorsulfonyl)oxaziridine has been used as the key step in the asymmetric synthesis of N,O,O,O-tetra-acetyl d-lyxo-phytosphingosine, jaspine B (pachastrissamine) and its C(2)-epimer.  相似文献   

4.
《Tetrahedron: Asymmetry》2000,11(20):4137-4151
A conjugated addition of benzylamine to methyl (4R,5S)-4,5-(isopropylidenedioxy)-(2E)-hexenoate 8a followed by lactonization under acidic condition proceeds to the formal total syntheses of l-daunosamine 4 and l-acosamine 2. On the other hand, direct conjugated addition of benzylamine to methyl (4S,5S)-4,5-epoxy-(2E)-hexenoate 5 and the subsequent intramolecular nucleophilic attack by the ester carbonyl group on the epoxy ring of the substrates leads to the formal total syntheses of d-acosamine 2 and d-ristosamine 1.  相似文献   

5.
In this study, forty-seven plant species belonging to seven families were analysed by GC and GC-MS for the contents of pharmacologically effective quinones: dithymoquinone (DTQ), thymohydroquinone (THQ), and thymoquinone (TQ). The results showed that detectable amounts (??1 mg kg?1) of at least one of these compounds have been found in three species of both Monarda (M. didyma, M. media, and M. menthifolia) and Thymus (T. pulegioides, T. serpyllum, and T. vulgaris) genera, two Satureja (S. hortensis and S. montana) species, and in single representatives of Eupatorium (E. cannabinum), Juniperus (J. communis), and Nigella (N. sativa) genera. The maximum contents of THQ and TQ were found in M. media aerial parts and M. didyma inflorescences (2674 and 3564 mg kg?1 of dried weight, respectively) in amounts significantly exceeding their maximum contents in N. sativa seeds (THQ = 530 mg kg?1 and TQ = 1881 mg kg?1), which are generally considered as the main natural source of both of these compounds. As a conclusion, M. didyma (bergamot) and M. media (purple bergamot) can be recommended as new prospective natural sources of THQ and TQ for pharmaceutical or food industries.   相似文献   

6.
Density (ρ), viscosity (η), and ultrasonic velocity (U) have been measured for binary mixtures of ethyl formate with methanol, ethanol, and 1-propanol at 303 K. From the experimental data, adiabatic compressibility (β), acoustic impedance (Z), viscous relaxation time (τ), free length (L f ), free volume (V f ), internal pressure (π i ), and Gibbs free energy (ΔG) have been deduced. It is shown that strength of intermolecular interactions between ethyl formate with selected 1-alcohols were in the order of methanol < ethanol < 1-propanol.  相似文献   

7.
A series of novel menthol derivatives containing 1,2,4-triazole-thioether moiety were designed, synthesized, characterized structurally, and evaluated biologically to explore more potent natural product-based antifungal agents. The bioassay results revealed that at 50 μg/mL, some of the target compounds exhibited good inhibitory activity against the tested fungi, especially against Physalospora piricola. Compounds 5b (R = o-CH3 Ph), 5i (R = o-Cl Ph), 5v (R = m,p-OCH3 Ph) and 5x (R = α-furyl) had inhibition rates of 93.3%, 79.4%, and 79.4%, respectively, against P. piricola, much better than that of the positive control chlorothalonil. Compounds 5v (R = m,p-OCH3 Ph) and 5g (R = o-Cl Ph) held inhibition rates of 82.4% and 86.5% against Cercospora arachidicola and Gibberella zeae, respectively, much better than that of the commercial fungicide chlorothalonil. Compound 5b (R = o-CH3 Ph) displayed antifungal activity of 90.5% and 83.8%, respectively, against Colleterichum orbicalare and Fusarium oxysporum f. sp. cucumerinum. Compounds 5m (R = o-I Ph) had inhibition rates of 88.6%, 80.0%, and 88.0%, respectively, against F. oxysporum f. sp. cucumerinu, Bipolaris maydis and C. orbiculare. Furthermore, compound 5b (R = o-CH3 Ph) showed the best and broad-spectrum antifungal activity against all the tested fungi. To design more effective antifungal compounds against P. piricola, 3D-QSAR analysis was performed using the CoMFA method, and a reasonable 3D-QSAR model (r2 = 0.991, q2 = 0.514) was established. The simulative binding pattern of the target compounds with cytochrome P450 14α-sterol demethylase (CYP51) was investigated by molecular docking.  相似文献   

8.
《Tetrahedron: Asymmetry》2007,18(4):513-519
Total synthesis of (4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles F 3 was achieved from the chiral bithiazole-type primary alcohols [(S)- and (R)-4-ethoxycarbonyl-2′-(1-hydroxymethylethyl)-2,4′-bithiazoles 8], which were obtained based on the enzymatic resolution of racemic alcohol 8 and its acetate 9. From a direct comparison by means of chiral HPLC between natural cystothiazole F 3 and synthetic compounds [(4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles 3], natural cystothiazole F 3 was found to be a 33:67 diastereomeric mixture [(4R,5S,6E,14S)-3:(4R,5S,6E,14R)-3 = 33:67].  相似文献   

9.
The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography–mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC50 of 42.57 μg/mL and EC50 of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors’ knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.  相似文献   

10.
Essential oils (EOs) of Clausena indica fruits, Zanthoxylum rhetsa fruits, and Michelia tonkinensis seeds were analyzed for their phytochemical profiles and biological activities, including anti-diabetes, anti-gout, and anti-leukemia properties. Sixty-six volatile compounds were identified by gas chromatography–mass spectrometry (GC–MS), in which, myristicin (68.3%), limonene (44.2%), and linalool (49.3%) were the most prominent components of EOs extracted from C. indica, Z. rhetsa, and M. tonkinensis, respectively. In addition, only EOs from C. indica inhibited the activities of all tested enzymes comprising α-amylase (IC50 = 7.73 mg/mL), α-glucosidase (IC50 = 0.84 mg/mL), and xanthine oxidase (IC50 = 0.88 mg/mL), which are related to type 2 diabetes and gout. Remarkably, all EOs from C. indica, Z. rhetsa (IC50 = 0.73 mg/mL), and M. tonkinensis (IC50 = 1.46 mg/mL) showed a stronger anti-α-glucosidase ability than acarbose (IC50 = 2.69 mg/mL), a known anti-diabetic agent. Moreover, the growth of leukemia cell Meg-01 was significantly suppressed by all EOs, of which, the IC50 values were recorded as 0.32, 0.64, and 0.31 mg/mL for EOs from C. indica, Z. rhetsa, and M. tonkinensis, respectively. As it stands, this is the first report about the inhibitory effects of EOs from C. indica and Z. rhetsa fruits, and M. tonkinensis seeds on the human leukemia cell line Meg-01 and key enzymes linked to diabetes and gout. In conclusion, the present study suggests that EOs from these natural spices may be promising candidates for pharmaceutical industries to develop nature-based drugs to treat diabetes mellitus or gout, as well as malignant hematological diseases such as leukemia.  相似文献   

11.
Kenji Mori 《Tetrahedron》2009,65(14):2798-699
All of the stereoisomers of the components of the female-produced sex pheromone of a moth, Lyclene dharma dharma, were synthesized. They are (R)- and (S)-6-methyl-2-octadecanone, (6R,14R)-, (6R,14S)-, (6S,14R)-, and (6S,14S)-6,14-dimethyl-2-octadecanone, and (R)- and (S)-14-methyl-2-octadecanone. Enantiomers of citronellal and methyl (S)-3-hydroxy-2-methylpropanoate were the starting materials, and olefin cross metathesis was employed as the key reaction.  相似文献   

12.
Perfluorophenazine regiospecifically reacted with monoalkyl-, dialkyl-, and arylamines to afford the corresponding 2-amino-substituted derivatives. 2-(Ethylamino)- and 2-(diethylamino)perfluorophenazine reacted with another molar amount of ethylamine and diethylamine to preferentially provide the 2,7-disubstituted derivatives, respectively. Perfluoro(2,7-dimethylphenazine) was allowed to react with ethylamine to give the 1-ethylamino derivative. These regiospecific reactions were explained by the density functional theory (DFT) calculations. Perfluorophenazine reacted with ethylenediamine to afford the 2,3-cyclized and N,N′-bis(2-perfluorophenazinyl) derivatives. These amino-substituted products showed UV-vis absorption (λmax) and fluorescence maxima (Fmax) in the range of 439-536 and 524-613 nm in hexane, respectively. Some of them exhibit intense fluorescence.  相似文献   

13.
Hypericum lanuginosum is one of the traditional medicinal plants that grows in the arid area of the Al-Naqab desert in Palestine and is used by Bedouins to heal various communicable and non-communicable illnesses. The purpose of this investigation was to estimate the total phenolic, flavonoid, and tannin contents of aqueous, methanol, acetone, and hexane H. lanuginosum extracts and evaluate their cytotoxic, anti-oxidative, and antimicrobial properties. Qualitative phytochemical tests were used to identify the major phytochemical classes in H. lanuginosum extracts, while total phenol, flavonoid, and tannin contents were determined using Folin–Ciocalteu, aluminum chloride, and vanillin assays, respectively. Moreover, a microdilution test was employed to estimate the antimicrobial activity of H. lanuginosum extracts against several microbial species. At the same time, the cytotoxic and free radical scavenging effects were evaluated using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assays, respectively. Quantitative examinations showed that the highest amounts of phenols, flavonoids, and tannins were noticed in the H. lanuginosum aqueous extract. Moreover, H. lanuginosum aqueous extract showed potent activity against methicillin-resistant Staphylococcus aureus even more than Amoxicillin and Ofloxacin antibiotics, with Minimum Inhibitory Concentrations (MICs) of 0.78 ± 0.01, 0, and 1.56 ± 0.03 µg/mL, respectively. Additionally, the aqueous extract exhibited the highest activity against Candida albicans and Epidermatophyton floccosum pathogens, with MIC values of 0.78 ± 0.01 µg/mL. Actually, the aqueous extract showed more potent antimold activity than Ketoconazole against E. floccosum with MICs of 0.78 ± 0.01 and 1.56 ± 0.02 µg/mL, respectively. Furthermore, all H. lanuginosum extracts showed potential cytotoxic effects against breast cancer (MCF-7), hepatocellular carcinoma (Hep 3B and Hep G2), and cervical adenocarcinoma (HeLa) tumor cell lines. In addition, the highest free radical scavenging activity was demonstrated by H. lanuginosum aqueous extract compared with Trolox with IC50 doses of 6.16 ± 0.75 and 2.23 ± 0.57 µg/mL, respectively. Studying H. lanuginosum aqueous extract could lead to the development of new treatments for diseases such as antibiotic-resistant microbes and cancer, as well as for oxidative stress-related disorders such as oxidative stress. H. lanuginosum aqueous extract may help in the design of novel natural preservatives and therapeutic agents.  相似文献   

14.
Single crystals of K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K3RESi2O7 that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment, while in K3LuSi2O7, containing the smallest of the rare earths, lutetium is found solely in an octahedral coordination environment. The structure of K3LuSi2O7 crystallizes in space group P63/mmc with a=5.71160(10) Å and c=13.8883(6) Å. The structures containing the remaining rare earths crystallize in the space group P63/mcm with the lattice parameters of a=9.9359(2) Å, c=14.4295(4) Å, (K3GdSi2O7); a=9.88730(10) Å, c=14.3856(3) Å, (K3TbSi2O7); a=9.8673(2) Å, c=14.3572(4) Å, (K3DySi2O7); a=9.8408(3) Å, c=14.3206(6) Å, (K3HoSi2O7); a=9.82120(10) Å, c=14.2986(2) Å, (K3ErSi2O7); a=9.80200(10) Å, c=14.2863(4) Å, (K3TmSi2O7); a=9.78190(10) Å, c=14.2401(3) Å, (K3YbSi2O7). The optical properties of the silicates were investigated and K3TbSi2O7 was found to fluoresce in the visible.  相似文献   

15.
1H-1,2-Diazaphenalene derivatives in which the pyridazine ring is ortho- and peri-fused to acenaphthene and acenaphthylene (1H-indeno[6,7,1-def]cinnolines) have been synthesized. It has been found that electrophilic attack on these compounds is directed at C6.  相似文献   

16.
Single-crystal X-ray diffraction analysis was used to determine the structure of a racemic diastereomer of the agricultural fungicide propiconazole [1-(2-(2,4-dichlorophenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole] and of two by-products (a symmetrical 1,3,4-triazole racemic-constitutional isomer and a propiconazole ditriazole analogue). All three crystalline racemic-diastereomers had (2R,4S)/(2S,4R)-stereochemistry in which then-propyl group was observed in atrans-to-phenyl disposition. Propiconazole (2R,4S)/(2S,4R)-diastereomer gives crystals belonging to the monoclinic space group P21,/a, and, at 293 K,a=8.1192(3),b=18.9769(6),c=10.7137(4) å,Β=99.765(3)?,V=1626.8(1) å3, Z=4,R(F)=0.060, andR w(F)=0.058. The constitutional isomer by-product (2R,4S)/(2S,4R)-1-(2-(2,4-dichlorophenyl)-4-n-pro-pyl-1,3-dioxolane-2-yl-methyl)-1-H-1,3,4-triazole gives crystals belonging to the monoclinic space group P21/n, and, at 293 K,a=11.1763(6),b=10.7716(4),c=14.5804(8) å,Β=107.445(4)?,V=1674.6(1) å3, Z=4,R(F)=0.043, andR w(F)=0.043. The ditriazole byproduct (2R,4S)/(2S,4R)-1-(2-(2-chloro-4-(1,2,4-triazole-1-yl)phenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole gives crystals belonging to the triclinic space group 1, and, at 193 K,a=5.3329(8),b=8.3738(7),c=20.240(2) å, α=84.213(6)?,Β=87.20(1)?,γ=86.23(1)?,V=896.5(2) å3, Z=2,R(F)=0.046, andR w(F)=0.051. The presence of both propiconazole (2R.4S)- and (2S,4R)-enantiomers enables the formation of a crystalline racemic modification, while the diastereomeric propiconazole (2R,4R)- and (2S,4S)-enantiomers are viscous oils. In the absence of its enantiomorphic partner, the propiconazole (2R,4S)- or (2S,4R)-enantiomers remain as viscous oils rather than form chiral crystals.  相似文献   

17.
The topological analysis and systematization of basis lattices in 1972 coordination compounds of Cu, Ag, Cd, and Zn containing organic ligands and layered complex groups (both isolated and interlaced with each other) are carried out by the TOPOS structural topological program package. The structures considered are most frequently based on the square (sql) or hexagonal (hcb) Shubnikov lattice (38.6 and 18.7%, respectively). The increased specificity of the sql and hcb lattices is due to specific features of coordination of the lattices facilitating their mutual penetration. Two types of interlacing of the layered groups (parallel and inclined) are revealed, and the former predominates.  相似文献   

18.
Organic nonlinear optical (NLO) material, N-succinopyridine (NSP), was synthesised and bulk single crystals were grown from aqueous solution using isothermal solvent evaporation technique. The stoichiometric form of NSP has been confirmed by carbon–hydrogen–nitrogen analysis. NSP crystallizes in orthorhombic system with non-centrosymmetric space group P212121 and unit cell dimensions a = 7.721(2) Å, b = 7.762(3) Å, c = 14.951(3) Å. The thermal stability, thermal decomposition and specific heat capacity of NSP have been investigated by thermogravimetric/differential thermal analysis, differential scanning calorimetric (DSC) analysis and modulated DSC analysis. A wide transparency window, 294–1,100 nm, useful for optoelectronic applications is indicated by UV–Vis–NIR studies. The NLO second harmonic generation efficiency analysis using Nd:YAG laser (1,064 nm) revealed that the SHG efficiency of NSP is about 1.2 times higher than that of standard potassium dihydrogen phosphate powder of comparable size and more importantly that it is phase-matchable. The room temperature mechanical behaviours of NSP have been tested using Vicker’s microhardness tester and the results were analysed through classical Mayer’s law. The dielectric behaviours such as dielectric constant, dielectric loss and ac conductivity of NSP single crystal have also been investigated as a function of frequency (20 Hz–1 MHz) and temperature (308–358 K).  相似文献   

19.
The microwave spectrum of cyclobutylisocyanate, c-C4H7NCO, has been investigated from 21,000 to 11,000 MHz and 11 transitions for the more stable equatorial-trans conformer were assigned. The rotational constants of the ground vibrational state have been determined and the molecule has been shown to be a near symmetric prolate rotor (К = ?0.99). The B and C rotational constants have been confidently determined to be B = 1508.68(3) and C = 1476.55(2) MHz, respectively, whereas the value for the A rotational constant of 6,891(302) MHz had a large uncertainty. Variable temperature (?100 to ?55 °C) studies of the infrared spectra (3,500–400 cm?1) of cyclobutylisocyanate dissolved in liquid xenon as well as the infrared spectra of the gas and solid have been recorded. In addition, the Raman spectra (3,600–100 cm?1) of the liquid have been investigated. These spectral data indicated the present of three conformers in the fluid states which are the equatorial-trans, equatorial-gauche, and axial-trans forms. The second part of the conformational name refers to the relative position of the NCO moiety relative to the alpha hydrogen. By utilizing four conformer pairs, an enthalpy difference of 131 ± 13 cm?1 (1.57 ± 0.16 kJ/mol) was obtained with the equatorial-trans conformer the more stable form, which is in good agreement with the ab initio predicted value of 137 ± 36 cm?1 (1.64 ± 0.43 kJ/mol). To aid in the vibrational assignment, ab initio and DFT calculations have been carried out by using a variety of basis sets up to 6-311G(3df,3pd).  相似文献   

20.
The biosynthesis of metallic nanoparticles is on a sharp rise as they have growing applications in environmental and biomedical sciences. This study reports an eco-friendly and cost-effective methodology for synthesizing biogenic silver nanoparticles (AgNPs) using the extract of Medicago sativa (M. sativa) cultivated in South Khorasan. The parameters used in the synthesis process were optimized to obtain uniformly distributed AgNPs in suitable sizes. The morphological, structural, and bonding characteristics of M. sativa extract-based AgNPs (MSE-AgNPs) were explored using FTIR, FESEM, EDS, TEM, XRD, UV–Vis, and DLS techniques. UV–Vis spectroscopy confirmed the formation of MSE-AgNPs by observing the typical surface plasmon resonance (SPR) peak at 419 nm. XRD, FESEM, TEM, and DLS analyses confirmed the formation of face-centered cubic (fcc) crystalline structure, spherical/elliptical morphology, the average particle size of 15–35 nm, and highly stable MSE-AgNPs. Green synthesized MSE-AgNPs indicated a significant antioxidant activity (78%) compared to M. sativa extract (32%). As such, the synthesized MSE-AgNPs revealed a potential antioxidant activity towards the DPPH radicals. The biologically synthesized MSE-AgNPs exhibited highly potential antibacterial and antifungal activities against Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus epidermidis, Enterococcus faecalis, Staphylococcus aureus, and Candida albicans with the minimum inhibitory concentration (MIC) values of 62.5, 125, 125, 1000, 125, 1000, and 31.25 µg/mL, respectively. In vitro cytotoxicity of the MSE-AgNPs against human fibroblast (HF) cells indicated a dose–response activity (with IC50 value of 18 µg/mL). Moreover, the AgNPs revealed efficient photocatalytic degradation of thymol blue (TB) as an anionic dye and malachite green (MG) as a cationic dye under sunlight and UV irradiations. Up to 94.37% and 90.12% degradation rates were obtained for MG and TB within only 100 min of UV irradiation. These observations signify that synthesized MSE-AgNPs can have great potential for biological and environmental applications.  相似文献   

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