A highly diastereoselective five-component synthesis of 1-(alkylimino)-5,5-dicyano-3a-aryloctahydro-3-oxacyclobuta[cd]pentalene-1a,2,5a,5b(2H,3aH)-tetracarboxylates

A novel one-pot, five-component synthesis of 1-(alkylimino)-5,5-dicyano-3a-aryloctahydro-3-oxacyclobuta[cd]pentalene-1a,2,5a,5b(2H,3aH)-tetracarboxylates is described. A mixture of phenacyl bromide, malononitrile, isocyanide, and two equivalents of a dialkyl acetylenedicarboxylate undergoes a novel 1:1:1:2 addition reaction at ambient temperature in absolute ethanol to produce diastereoselectively the title compounds in good yields.     

Mononuclear copper(II) complexes of bis-triazole-based macrocyclic Schiff base hydrazones: direct synthesis,EPR studies,magnetic and thermal properties

Mononuclear copper(II) complexes of 1,2,4-triazole-based Schiff base macrocyclic hydrazones, III and IV, have been reported. The prepared amorphous complexes have been characterized by spectroscopic methods, electron spray ionization mass spectrometry, and elemental analysis data. Electrochemical studies of the complexes in DMSO show only one quasi-reversible reduction wave at +0.43 V (ΔE = 70 mV) and +0.42 V (ΔE = 310 mV) for III and IV, respectively, which is assigned to the Cu(II) → Cu(I) reduction process. Temperature dependence of magnetic susceptibilities of III and IV has been measured within an interval of 2–290 K. The values of χ_M at 290 K are 1.72 × 10^?3 cm³ mol^?1 and 1.71 × 10^?3 for III and IV, respectively, which increases continuously upon cooling to 2 K. EPR spectra of III and IV in frozen DMSO and DMF were also reported. The trend g_|| > g⊥ > g_e suggests the presence of an unpaired electron in the d_x2?y2 orbital of the Cu(II) in both complexes. Furthermore, spectral and antimicrobial properties of the prepared complexes were also investigated.     

Efficient Catalytic and Thermal Syntheses of Novel Thiadiazole,Triazole, Benzothiazole,and Fused Quinazoline Derivatives

Russian Journal of Organic Chemistry - A thiourea derivative, 4-chloro-N-[(4-chlorophenyl)carbamothioyl]benzamide, was oxidized with iodine in acetic acid to give the corresponding disulfide,...     

Physiological and Immunological Changes Associated with Oral Microbiota When Using a Thermoplastic Retainer

Background: The study examined the oral microbiota, physiological and immunological changes in patients using thermoplastic retainers during three months of use. Methods: The study included several steps. Firstly, 10 swabs were collected from the buccal and palatal surfaces of the teeth of the patients, approximately 2 mL of saliva was collected from the same patients and 2 mL of saliva was collected from 10 healthy people to measure the pH and secretory IgA level. This was followed by the isolation and identfication of the bacterial isolates in the patient samples. Then, isolate susceptibility toward chlorhexidine (CHX) and their adhesion ability to thermoplastic retainer surfaces was measured. In addition to that the study estimated the numbers of Lactobacillus and Streptooccus mutans colonies during three months and finally, a comparsion of pH acidity and IgA level between the patients and healthy people was performed. The results showed the predominant bacteria during the three months were Lactobacillus spp. and Streptococcus spp. followed by different rates of other bacteria. Raoultella ornithinolytica showed more resistance to CHX while Lactobacillus spp. showed more sensitivity. Streptococcus mutans colony levels were higher than Lactobacillus spp. colonies during the three months, also S. mutans had the highest value in adherence to retainer thermoplastic. Finally, pH acidity showed a highly significant difference (p ≤ 0.05) in the third month, like IgA levels (p ≤ 0.05). Conclusions: According to the results obtained from the current study, the researchers noted that the thermoplastic retainers helped change the oral cavity environment.     

Kinetic,isotherm, and mechanism investigations of the removal of nitrate and nitrite from water by the synthesized hydrotalcite Mg–Al

Research on Chemical Intermediates - The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence...     

Gel-assisted synthesis of anatase TiO2 nanoparticles and application for electrochemical determination of L-tryptophan

Anatase titanium dioxide nanoparticles (TiO₂-NPs) were synthesized with and without gelatin via the sol-gel method. The TiO₂-NPs were characterized by a number of techniques, such as thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV-Vis). The particle sizes of the TiO₂-NPs prepared with and without gelatin were ～13 and ～17 nm, respectively. The main advantage of using gelatin as a stabilizing agent is that it provides long-term stability for nanoparticles by preventing particles agglomeration. The results indicated that gelatin was a reliable green stabilizer, which can be used as a polymerization agent in the sol-gel method for synthesis of tiny size TiO₂-NPs. Moreover, the composite film was prepared by synthesized TiO₂-NPs nanoparticles and multi wall carbon nanotube (MWNT) on glassy carbon electrode (TiO₂-MWNT/GCE). The TiO₂-MWNT/GCE responded linearly to L-tryptophan (L-Trp) in the concentration of 1.0 × 10^?6 to 1.5 × 10^?4 M with detection limit of 5.2 × 10^?7 M at 3 using amperometry. The studied sensor exhibited good reproducibility and long-term stability.     

Electrochemical Determination of Dextromethorphan on Reduced Graphene Oxide Modified Screen‐Printed Electrode after Electromembrane Extraction

In this paper, electromembrane extraction coupled with differential pulse voltammetry (DPV) on a reduced graphene oxide modified screen‐printed carbon electrode (RGO‐SPCE) for the determination of dextromethorphan (DXM) in urine and plasma has been described. DXM migrated from 4 mL of a donor phase across a thin layer of 2‐nitrophenyl octyl ether (NPOE) immobilized in the pores of a porous hollow fiber, into a 20 µL acceptor phase (HCl) present inside the lumen of the fiber. Then, 15 µL of a 0.1 M NaOH solution was added to the acceptor phase and the mixture was analyzed using DPV.     

Plasma-Assisted Reaction Chemical Ionization for Elemental Mass Spectrometry of Organohalogens

We present plasma-assisted reaction chemical ionization (PARCI) for elemental analysis of halogens in organic compounds. Organohalogens are broken down to simple halogen-containing molecules (e.g., HBr) in a helium microwave-induced plasma followed by negative mode chemical ionization (CI) in the afterglow region. The reagent ions for CI originate from penning ionization of gases (e.g., N₂) introduced into the afterglow region. The performance of PARCI-mass spectrometry (MS) is evaluated using flow injection analyses of organobromines, demonstrating 5–8 times better sensitivities compared with inductively coupled plasma MS. We show that compound-dependent sensitivities in PARCI-MS mainly arise from sample introduction biases.

含吡啶的大环席夫碱锰(Ⅱ)配合物:合成、表征及抗菌性质(英文)

在Mn髤模板作用下,2,6-diacetylpyridine(DAP)及合适链状胺化合物通过[1+1]环缩合反应,合成了3个大环席夫碱配合物,并进行了红外、元素分析、质谱及电导率等表征及研究。测得了配合物[MnL1(CH3CN)](ClO4)2的晶体结构,中心离子呈现出稍微扭曲的五角锥配位构型。研究了配合物对S.aureus(ATCC 6633),B.cereus(ATCC 7064),C.xerosis(ATCC 373)(gram-positive bacterial strains),E.coli(PTCC 10009),K.pneuomoniae(MTCC 109),and P.vulgaris(lio)(gram-negative bacterial strains)的抗菌活性。结果显示[MnL3](ClO4)2抗菌活性明显优于[MnL1(CH3CN)](ClO4)2and[MnL2](ClO4)2。在25℃条件下0.1 mol·L-1 KCl溶液中,通过电位计量法测定了化合物的质子化常数。