Studies in the chemistry of erythrina alkaloid derivatives—III : Two isomers of 2,3,4,4a,5,6,7,7a,8,9,10,11-dodecahydro-2,10-dioxo-1H-benzo[d]naphthalene

Diketone 2,3,4,4a,5,6,7,7a,8,9,10,11-dodecahydro-2,10-dioxo-1H-benzo[d]-naphthalene prepared by annulation of N-(1-cyclohexenyl)pyrrolidine with vinyl methyl ketone, was found to consist of two stereoisomers. Theoretical dipole moments of these were calculated, and their structures were shown by moment dipole measurements to be cis A/B, cis A/C and trans A/B, cis A/C, respectively. The isomer trans A/B, cis A/B was converted into trans A/B, cis A/C dodecahydro-1H-benzo[d]naphthalene by the Wolff-Kishner reduction.     

Multifunctional zig-zag-shaped D-π-A-π-D emitters with high conjugation extent for blue FOLEDs and host for PHOLEDs

We have synthesized zig-zag shaped, meta- and para-linked D-π-A-π-D blue emitters, m-BTPAPy and p-BTPAPy based on a non-symmetrical connection strategy of two identical π-conjugated groups. The phenanthrimidazole moiety coupled to pyridine via naphthyl spacer by para- and meta-linking modes. Both m-BTPAPy (T_d/T_g, °C: 564/281) and p-BTPAPy (T_d/T_g, °C: 502/246) exhibit excellent thermal stability and can form a stable amorphous film. Changing the connection strategy from para to meta mode, m-BTPAPy shows deep blue emission with CIE (0.15, 0.07). The highly twisted m-BTPAPy exhibit higher Photoluminescence quantum yield (PLQY)_s/f of 0.98/0.85 than p-BTPAPy (0.95/0.80) owing to the suppression of intermolecular stacking. The non-doped blue device (BOLEDs) with multifunctional m-BTPAPy/p-BTPAPy show external quantum efficiency (EQE) of 7.12/5.12% with small roll-off efficiency of 1.68/2.14%, power efficiency (PE) of 5.92/5.42 lm/W, the luminance of 58675/76234 cd/m², and current efficiency (CE) of 6.12/5.86 cd/A. The non-doped device using m-BTPAPy/p-BTPAPy as both emitting and electron-transporting material exhibit luminance of 40671/49539 cd/m², CE of 5.01/5.08 cd/A, PE of 4.68/4.76 lm/W, EQE of 6.12/4.81%, roll-off efficiency of 1.63/1.87%, and CIE (0.15, 0.10)/(0.15, 0.11). These bipolar materials with high triplet energy were employed as hosts in green and red PhOLEDs. The green (m-BTPAPy: Ir(ppy)₃)/red device (m-BTPAPy: Ir(MDQ)₂(acac)) exhibit maximum EQE of 29.85/20.09%, luminance of 79523/42412 cd/m², CE of 78.62/27.56 cd/A, and PE of 72.36/23.86 lm/W, and CIE (0.33, 0.60)/(0.65,0.33).     

Insecticidal Activity of Extracts,Fractions, and Pure Molecules of Cissampelos pareira Linnaeus against Aphid,Aphis craccivora Koch

Aphis craccivora Koch is a polyphagous and major pest of leguminous crops causing significant damage by reducing the yield. Repeated application of synthetic insecticides for the control of aphids has led to development of resistance. Therefore, the present study aimed to screen the insecticidal activity of root/stem extracts/fractions, and pure molecules from Cissampelos pareira Linnaeus against A. craccivora for identification of lead(s). Among root extract/fractions, the n-hexane fraction was found most effective (LC₅₀ = 1828.19 mg/L) against A. craccivora, followed by parent extract (LC₅₀ = 2211.54 mg/L). Among stem extract/fractions, the n-hexane fraction (LC₅₀ = 1246.92 mg/L) was more effective than the water and n-butanol fractions. Based on GC and GC-MS analysis, among different compounds identified in the n-hexane fraction of root and stem, ethyl palmitate (known to possess insecticidal activity) was present in the highest concentration (24.94 to 52.95%) in both the fractions. Among pure molecules, pareirarineformate was found most effective (LC₅₀ = 1491.93 mg/L) against A. craccivora, followed by cissamine (LC₅₀ = 1556.31 mg/L). Parent extract and fractions of C. pareira possess promising activity against aphid. Further, field bio-efficacy studies are necessary to validate the current findings for the development of botanical formulation.     

Insecticidal and Enzyme Inhibition Activities of Leaf/Bark Extracts,Fractions, Seed Oil and Isolated Compounds from Triadica sebifera (L.) Small against Aphis craccivora Koch

Aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is a major sap-sucking insect pest of leguminous crops and also transmits plant viruses, leading to economic yield loss. Indiscriminate and repeated use of insecticides for control of aphid leads to the development of resistance, and is harmful to the environment, non-target organisms, etc. Plant-based extracts/seed oils (SO) are the best alternatives to insecticides. Insecticidal activities of Triadica sebifera have not been reported against A. craccivora and other insect pests to date. In the current study, the main objective was to study the insecticidal activities of leaf/bark extracts/fractions, seed oil, isolated compounds, and their combinations against A. craccivora. Results showed that, among the extracts, ethanolic bark extract 80% (LC₅₀ = 5115.98 mg/L) was more effective against A. craccivora. Among fractions, the n-hexane fraction of leaves (LC₅₀ = 425.73 mg/L) and the ethyl acetate fraction of bark (LC₅₀ = 813.45 mg/L) were promising. Among compounds, gallic acid was the most effective (LC₅₀ = 1303.68 mg/L) compared to shikimic acid and quercetin. SO (LC₅₀ = 850.94 mg/L) was superior compared to extracts/fractions/compounds. All the combinations showed toxicity and synergistic activity. Leaf/bark extracts and SO significantly inhibited the AChE and GST activity in A. craccivora. Based on field bio-efficacy, the leaf extract/SO or their combinations can be recommended for the control of aphids.     

Comparative potentiality of Kans grass (Saccharum spontaneum) and Giant reed (Arundo donax) as lignocellulosic feedstocks for the release of monomeric sugars by microwave/chemical pretreatment

Two-stage microwave (microwave/NaOH pretreatment followed by microwave/H₂SO₄ pretreatment) was used to release monomeric sugars from Kans grass (Saccharum spontaneum) and Giant reed (Arundo donax). The optimum pretreatment conditions were investigated, and the maximum monomeric sugar yields were compared. The microwave-assisted NaOH and H₂SO₄ pretreatments with a 15:1 liquid-to-solid ratio were studied by varying the chemical concentration, reaction temperature, and reaction time to optimize the amount of monomeric sugars. The maximum amounts of monomeric sugars released from microwave-assisted NaOH pretreatment were 6.8 g/100 g of biomass [at 80 °C/5 min, 5 % (w/v) NaOH for S. spontaneum and at 120 °C/5 min, 5 % (w/v) NaOH for A. donax]. Furthermore, the maximum amounts of monomeric sugars released from microwave-assisted H₂SO₄ pretreatment of S. spontaneum and A. donax were 33.8 [at 200 °C/10 min, 0.5 % (w/v) H₂SO₄] and 31.9 [at 180 °C/30 min, 0.5 % (w/v) H₂SO₄] g/100 g of biomass, respectively. The structural changes of S. spontaneum and A. donax were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy.     

Study on Quality Control of Compound Anoectochilus roxburghii (Wall.) Lindl. by Liquid Chromatography–Tandem Mass Spectrometry

Compound Anoectochilus roxburghii (Wall.) Lindl. (A. roxburghii) oral liquid (CAROL) is a hospital preparation of A. roxburghii and Ganoderma lucidum (G. lucidum), which have hepatoprotective effects. Eight active components (five nucleosides/nucleobases and three triterpenoid acids) in CAROL, A. roxburghii, and G. lucidum were simultaneously detected by high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS). The multiple reaction monitoring (MRM) mode was applied for the detection of analytes. These eight compounds were separated well within 12 min and quantified using the internal standard working curve method. The method showed good linearity (R² > 0.9935) and high sensitivity (limit of detection = 0.29 ng/mL). The analyte recovery ranged from 85.07% to 97.50% (relative standard deviation < 3.31%). The content of the target analytes in four batches of CAROL, and the raw materials of G. lucidum and A. roxburghii from the five regions was determined using this method. The contents of guanosine and ganoderic acid A in four batches of oral liquid were high and stabilized and could be recommended as quality markers (Q-marker) for CAROL. Simultaneous qualitative and quantitative analysis of nucleosides and triterpenoid acids in CAROL, A. roxburghii, and G. lucidum by LC–MS/MS based on the MRM model was reported for the first time. The proposed method provides a sensitive, rapid, and reliable approach for the quality control of Chinese medicinal products.     

Chemical Composition and Antifungal Activity of Myrcia multiflora and Eugenia florida Essential Oils

The essential oils of three specimens of Myrcia multiflora (A, B and C) and Eugenia florida were extracted by hydrodistillation, and the chemical compositions from the essential oils were identified by gas chromatography and flame ionization detection (CG/MS and CG-FID). The fungicide potential of the EOs against five fungicide yeasts was assessed: Candida albicans INCQS-40175, C. tropicalis ATCC 6258, C. famata ATCC 62894, C. krusei ATCC 13803 and C. auris IEC-01. The essential oil of the specimen Myrcia multiflora (A) was characterized by the major compounds: α-bulnesene (26.79%), pogostol (21.27%) and δ-amorphene (6.76%). The essential oil of the specimen M. multiflora (B) was rich in (E)-nerolidol (44.4%), (E)-γ-bisabolene (10.64%) and (E,E)-α-farnesene (8.19%), while (E)-nerolidol (92.21%) was the majority of the specimen M. multiflora (C). The sesquiterpenes seline-3,11-dien-6-α-ol (12.93%), eremoligenol (11%) and γ-elemene (10.70%) characterized the chemical profile of the EOs of E. florida. The fungal species were sensitive to the essential oil of M. multiflora (B) (9–11 mm), and the lowest inhibitory concentration (0.07%) was observed in the essential oil of M. multiflora (A) against the yeasts of C. famata. Fungicidal action was observed in the essential oils of M. multiflora (A) against C. famata, with an MIC of 0.78 µL/mL and 3.12 µL/mL; C. albicans, with an MFC of 50 µL/mL and M. multiflora (C) against C. albicans; and C. krusei, with a MFC of 50 µL/mL.     

Optimization of Xylanase Production by Filamentous Fungi in Solid-State Fermentation and Scale-up to Horizontal Tube Bioreactor

Five microorganisms, namely Aspergillus niger CECT 2700, A. niger CECT 2915, A. niger CECT 2088, Aspergillus terreus CECT 2808, and Rhizopus stolonifer CECT 2344, were grown on corncob to produce cell wall polysaccharide-degrading enzymes, mainly xylanases, by solid-state fermentation (SSF). A. niger CECT 2700 produced the highest amount of xylanases of 504?±?7 U/g dry corncob (dcc) after 3 days of fermentation. The optimization of the culture broth (5.0 g/L NaNO₃, 1.3 g/L (NH₄)₂SO₄, 4.5 g/L KH₂PO₄, and 3 g/L yeast extract) and operational conditions (5 g of bed loading, using an initial substrate to moistening medium of 1:3.6 (w/v)) allowed increasing the predicted maximal xylanase activity up to 2,452.7 U/g dcc. However, different pretreatments of materials, including destarching, autoclaving, microwave, and alkaline treatments, were detrimental. Finally, the process was successfully established in a laboratory-scale horizontal tube bioreactor, achieving the highest xylanase activity (2,926 U/g dcc) at a flow rate of 0.2 L/min. The result showed an overall 5.8-fold increase in xylanase activity after optimization of culture media, operational conditions, and scale-up.     

Strong magnetoelectric coupling in sol–gel derived multiferroic (Pb0.76Ca0.24)TiO3–CoFe2O4 composite films

A multilayer heterostructure composite thin films consisting of alternating layers (Pb_0.76Ca_0.24)TiO₃ (PCT) and CoFe₂O₄ (CFO) were grown on Pt/Ti/SiO₂/Si(100) substrate by a sol–gel process. X-ray measurements indicated high quality of crystallization of both PCT and CFO layers. The magnetic and ferroelectric properties of the composite were investigated. Well-defined polarization vs. electric field (P–E) and magnetic hysteresis (M-H) loops were obtained. A strong magnetoelectric (ME) response was observed in the sample which was subjected to an alternating magnetic field, and a high ME voltage coefficient α_E = 870 mV/Oe cm was obtained for the composite thin films when applied magnetic field parallel to the sample plane.     

Novel naphthalene-based bis-pyridinium compounds with pronounced antibacterial activity

Novel para-substituted bis-pyridinium compounds containing 2,7-dioxynaphthalene spacer were synthesized in two simple steps from the corresponding dihydroxy-naphthalene. The microbiological study on five reference (E. coli ATCC 25922, K. pneumoniae ATCC 70060, S. aureus ATCC 43300, P. aeruginosa ATCC27853, and A. baumannii ATCC 15308) and five clinical (E. coli B-3421/19,K. pneumoniae B-2523/18, S. aureus B-8648, P. aeruginosa B-2099/18 and A. baumannii B-2926/18) bacterial strains showed promising range of antibacterial properties for these biocides, compared to modern sanitizers.     

High performance liquid chromatographic determination of diazinon, permethrin, DEET (N, N-diethyl-m-toluamide), and their metabolites in rat plasma and urine

A rapid method was developed for the analysis of the insecticide (A) diazinon (O,O-diethyl O-2-isopropyl-6-methylpyridimidinyl) phosphorothioate, its metabolites (B) diazoxon (O,O-diethyl O-2-isopropyl-6-methylpyridimidinyl) phosphate, and (C) 2-isopropyl-6-methyl-4-pyrimidinol, the insecticide (D) permethrin [3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid (3-phenoxyphenyl)methylester], its metabolites (E) m-phenoxybenzyl alcohol, and (F) m-phenoxybenzoic acid, the insect repellent (G) DEET (N,N-diethyl-m-toluamide), and its metabolites (H) m-toluamide and (I) m-toluic acid in rat plasma and urine. The method is based on using C₁₈ Sep-Pak cartridges (Waters Corporation, Milford, Mass., U.S.A.) for solid phase extraction and high performance liquid chromatography with a reversed phase C₁₈ column, and absorbance detection at 230 nm for compounds A, B, and C, and at 210 nm for compounds D–I. The compounds were separated using a gradient from 1% to 99% acetonitrile in water (pH 3.0) at a flow rate ranging between 1 and 1.7 mL/min in a period of 17 min. The limits of detection were ranged between 20 and 100 ng/mL, while limits of quantification were 80–200 ng/mL. The relationship between peak areas and concentration was linear over a range of 100–1000 ng/mL. This method was applied to determine the above insecticides and their metabolites following dermal administration in rats.     

Vibrational and theoretical studies on CF3SNH2: A compound containing an SNH2 group

The structure and conformational behaviour of CF₃SNH₂ have been studied by ab initio calculations (HF/3-21G* (with additional d-functions on nitrogen, α_d: 0.8) and HF/6-31G**) and vibrational spectroscopy. Both theoretical methods predict a trans form (CS bond in trans position with respect to the N lone pair, C_s symmetry) to be more stable than the corresponding cis conformer by 1.5 and 0.7 kcal/mol, respectively. The calculated barriers to inversion are 2.7 (HF/3-21G*) and 1.6 kcal/mol (HF/6-31G**). A depolarized band observed in the Raman spectra of the liquid is in accordance with the existence of a plane of symmetry in the molecule. A normal coordinate analysis was performed for the A′ modes of vibration.     

Phase transformation in Y2[Pt(CN)4]3-21H2O

Y₂[Pt(CN)₄]₃21H₂O (YCP) crystallizes in a columnar structure type with a mean in-chain PtPt distance of R = 3.18 A. At T_c = (218.5 ± 1) K YCP undergoes a first order phase transformation which is investigated spectroscopically (polarized emission) and thermodynamically (specific heat and differential thermal analysis). It is possible to record polarized emission spectra from the high temperature phase (phase I) T >T_c, the low temperature phase (phase II) T <T_c, and the supercooled phase I. From the spectroscopic data we deduce a PtPt distance reduction (at T_c) of ΔR = (?0.04 ± 0.005) A. The enthalpy of the transition from phase I to phase II is about +1500 J/mole.     

1H 13C NMR investigation of E/Z-isomerization around CN bond in the trans-alkene-Pt(II)imine complexes of some ketimines and aldimines

Ketimines (K1, K2) and aldimines (A1, A2, and A3) were prepared from unsubstituted acetophenone and/or benzaldehyde and primary amines (i-PrNH₂, i-BuNH₂ and t-BuNH₂). These imines were reacted with Zeise’s salt (potassium ethenetrichloroplatinate(II)) to produce the respective complexes, namely, PtK1, PtK2, PtA1, PtA2, and PtA3. ¹H, ¹³C, and ¹⁹⁵Pt-chemical shifts of the ligands and their complexes were studied to investigate the nature and mode of isomerization around CN bond. The aldimines and their complexes were obtained as a single isomer. On the other hand, the ketimines and their complexes were obtained as a mixture of E/Z-isomers. It was found that the aldimine- and ketimine-platinum complexes undergo slow E/Z-isomerization in solution as evidenced from NMR spectra.     

Phenolic proton transfer to the 1,2 double bond in the molecular ion of trans-1,2-tetrahydrocannabinol

It is known that the molecular ion of trans-1,6-tetrahydrocannabinol (1,6-THC) with m/e 314 decomposes via a retro Diels-Alder reaction to fragment m/e 246, which then loses a Me radical to give the ion m/e 231 (cf Scheme 1).¹A similar breakdown is found for trans-1,2-tetrahydrocannabinol (1,2-THC), suggesting a shift of the double bond from the 1,2 to the 1,6 position in its molecular ion.Methylation of the phenolic OH group in trans-1,2-tetrahydrocannabinol however, shows that the phenolic proton transfer to the 1,2 double bond (cf Scheme 2) is much more important (～ 35–80%) than simple double bond migration (～ 20%; Scheme 3) in the formation of fragment m/e 231.     

Synthesis and molecular structure of niobocene(tricarbonyl)(π-cyclopentadienyl)molybdenum with metalmetal bond and unusual coordination of carbonyl groups

(C₅H₅)₂NbBH₄ reacts with C₅H₅M(CO)₃Me in toluene solution in the presence of Et₃N to give binuclear complexes (C₅H₅)₂NbM(CO)₃C₅H₅ where M is Mo or W (IV and V, respectively). The structure of IV has been studied by X-ray diffraction (the crystals are orthorhombic, a 12.748(5), b 16.745(6), c 14.314 $\text{A/ac>}\text{?}$;; Z = 8, space group of Pbca, automatic difractometer Syntex P2_I, λ(Mo-K_α, 1382 reflections, R = 0.056, R_w = 0.058). Molecule IV contains a wedge-like sandwich (π-C₅H₅)₂Nb (NbC 2.37–2.48, CC (av) 1.42 $\text{A/ac>}\text{?}$;, angle between ring planes 49°) linked with the (π-C₅H₅)Mo(CO) fragment by a direct NbMo bond (3.073 $\text{A/ac>}\text{?}$;) and two bridging CO groups, one nonsymmetrically bonded through the carbon atom only (CO 1.17, NbC 2.53, MoC 2.02 $\text{A/ac>}\text{?}$;) and the other σ-bonded to Mo (MoC 1.944 $\text{A/ac>}\text{?}$;) and π-bonded to Nb (CO 1.22, NbC 2.22, NbO 2.26 $\text{A/ac>}\text{?}$;). Three types of carbonyl groups present in IV give rise to strong IR bands at 1870, 1700 and 1560 cm^?1 assigned to the terminal, μ-bridging and σ, π-bridging CO groups respectively. Complex IV has a similar structure. The electronic structure of IV and its dissociation across the NbMo bond are discussed.     

New alkaline earth equiatomic phases: SrAu and BaAu

The phases SrAu and BaAu were synthesized and characterized structurally. SrAu,mP40, space groupP/2₁m, a = 40.13(2), b = 4.697(1), c = 6.192(4)A?, β = 94.21(6)°,Z = 20, is a new stacking variant of the FeBCrB type, with Jagodzinski notationhch₂ch₂chc. The structure was refined from single crystal diffractometric data withR = 0.090. BaAu,oP8, space groupPnma,a = 8.338(5), b = 4.925(1), c = 6.390(4)A?,Z = 4, crystallizes in the FeB structure type. A general correlation among theAB equiatomic phases formed by the alkaline earths with VIII to IVB group elements is found by reporting theBB chain angle against the combinationR^AB_σ = |(r^A_s + r^A_p) ? (r^B_s + r^B_p)| with Zunger'sr orbital radii.     

A Simple and Efficient Two-Dimensional High-Speed Counter-Current Chromatography Linear Gradient and Isocratic Elution Modes for the Preparative Separation of Coumarins from Roots of Toddalia asiatica (Linn.) Lam.

Toddalia asiatica (L.) Lam. (Rutaceae) has shown a broad spectrum of biological properties, such as anti-inflammatory, antioxidant, antimicrobial, anti-HIV, and anticancer properties. The present study is concerned with the separation of the main components with broad partition coefficients (K_D values) from T. asiatica, using linear gradient high-speed counter-current chromatography (LGCCC) combined with an off-line two-dimensional (2D) mode. Similar to the binary gradient HPLC, the LGCCC mode is operated by the adjustment of the proportion between the mobile phase of 5:5:1:9 (v/v) (pump A) and 5:5:4.5:5.5 (v/v) (pump B) in an n-hexane/ethyl acetate/methanol/water solvent system. The off-line 2D-CCC mode was used in this study for the secondary separation of two similar K_D value compounds with n-hexane/ethyl acetate/methanol/water (5:5:4:6, v/v). Notably, six coumarins, namely, tomentin (1), toddalolactone (2), 5,7,8-trimethoxycoumarin (3), mexoticin (4), isopimpinellin (5), and toddanone (6), were efficiently separated. The structures of the pure compounds were elucidated by spectral techniques and compared with the literature.     

An Electron Diffraction and Crystal Chemical Investigation of Oxygen/Fluorine Ordering in Niobium Oxyfluoride, NbO2F

A careful electron diffraction study of the ReO₃-type oxyfluoride NbO₂F has revealed the presence of characteristic transverse polarized planes of diffuse intensity running through the G±〈hk(1/3)〉^* regions of reciprocal space as well as continuous rods of diffuse intensity running through the G±〈(1/2)(1/2)ξ〉^* regions of reciprocal space. The continuous planes of diffuse intensity in reciprocal space (perpendicular to each of the major crystal directions a, b and c) imply the existence of one-dimensional, oxygen/fluorine-ordered columns of atoms along 〈001〉 in real space but with no lateral correlation in the ordering from such 〈001〉 column to the next. The continuous lines of diffuse intensity along the 〈(1/2)(1/2)ξ〉^* directions of reciprocal space are ascribed to Rigid Unit Mode (RUM) rotations of the constituent MX₆ octahedral framework. A combination of bond-valence arguments and simple structure factor calculations are used to support this argument.     

Enantioselective total synthesis of (−)-myrifabral A and B

A catalytic enantioselective approach to the Myrioneuron alkaloids (−)-myrifabral A and (−)-myrifabral B is described. The synthesis was enabled by a palladium-catalyzed enantioselective allylic alkylation, that generates the C(10) all-carbon quaternary center. A key N-acyl iminium ion cyclization forged the cyclohexane fused tricyclic core, while vinyl boronate cross metathesis and oxidation afforded the lactol ring of (−)-myrifabral A. Adaptation of previously reported conditions allowed for the conversion of (−)-myrifabral A to (−)-myrifabral B.

A catalytic enantioselective approach to the Myrioneuron alkaloids (−)-myrifabral A and (−)-myrifabral B is described.