Thermal properties of sodium acetylacetonate

Sodium acetylacetonate was prepared by the interaction of acetyl acetone with sodium hydroxide. The thermal conductivity, phonon velocity, mean free path, Yong's modulus, and the thermal expansion coefficient were studied. The thermal conductivity of the material decreases with increasing temperature due to the thermal lattice scattering of phonons. The velocity of phonons is also decreased due to the perturbation of thermal phonons. The linear thermal expansion coefficient increases with temperature due to the weakness of the attractive forces between the small Na⁺ cations and bulkier acetylacetonate anions in the lattice.

---

Zusammenfassung Natriumacetylacetonat wurde durch die Wechselwirkung zwischen Acetylaceton und Natriumhydroxid gewonnen. Es wurde die Wärmeleitfähigkeit, die Phononengeschwindigkeit, die mittlere freie Wegstrecke, das Elastizitätsmodul und der Wärmeausdehnungskoeffizient untersucht. Die Wärmeleitfähigkeit der Substanz nimmt wegen der thermischen Gitterstreuung der Phononen mit steigender Temparatur ab. Die Geschwindigkeit der Phononen nimmt auf Grund der Perturbierung der thermischen Phononen ebenfalls ab. Der lineare Wärmeausdehnungskoeffizient steigt mit zunehmender Temperatur an, was auf die schwachen Anziehungskräfte zwischen den kleinen Na⁺ Ionen und den massigen Acetylacetonat-Anionen im Gitter zurückzuführen ist.

     

High-throughput screening of enzyme libraries: thiolactonases evolved by fluorescence-activated sorting of single cells in emulsion compartments

Single bacterial cells, each expressing a different library variant, were compartmentalized in aqueous droplets of water-in-oil (w/o) emulsions, thus maintaining a linkage between a plasmid-borne gene, the encoded enzyme variant, and the fluorescent product this enzyme may generate. Conversion into a double, water-in-oil-in-water (w/o/w) emulsion enabled the sorting of these compartments by FACS, as well as the isolation of living bacteria cells and their enzyme-coding genes. We demonstrate the directed evolution of new enzyme variants by screening >10(7) serum paraoxonase (PON1) mutants, to yield 100-fold improvements in thiolactonase activity. In vitro compartmentalization (IVC) of single cells, each carrying >10(4) enzyme molecules, in a volume of <10 femtoliter (fl), enabled detection and selection despite the fast, spontaneous hydrolysis of the substrate, the very low initial thiolactonase activity of PON1, and the use of difusable fluorescent products.     

Asymmetric Synthesis of alpha-Amino Phosphonic Acids by Diastereoselective Addition of Trimethyl Phosphite onto Chiral Oxazolidines(1)

A simple and general asymmetric synthesis of alpha-amino phosphonic acids is described. The method involves the highly selective addition of trialkyl phosphite onto various chiral oxazolidines. Oxazaphosphorinanes thus obtained with an excellent diastereoselectivity furnish the corresponding (S)-alpha-substituted amino phosphonic acids in good overall yields and high ee (77-->97%) after simple deprotection.     

Cathodic adsorptive stripping square-wave voltammetric determination of nifedipine drug in bulk,pharmaceutical formulation and human serum

Nifedipine is a calcium-channel antagonist drug used in the management of angina pectoris and hypertension through inhibition of calcium influx. A fully validated sensitive cathodic adsorptive stripping square-wave voltammetry procedure was optimized for the determination of the drug at trace levels. The procedure was based on the reduction of the nitrophenyl group after the interfacial accumulation of the drug onto a hanging mercury drop electrode in Britton-Robinson buffer of pH 11.0. The optimal conditions of the procedure were found to be: accumulation potential=-0.9 V vs. Ag/AgCl/KCl(s)), accumulation time=30 s, scan increment=10 mV, pulse amplitude=50 mV and frequency=120 Hz. Under these conditions, a well-defined peak was obtained; its peak current showed a linear dependence on drug concentration in the range of 2x10(-9)-2x10(-7) mol L(-1) bulk nifedipine. The mean recoveries based on eight replicate measurements for 1x10(-8) and 5x10(-8) mol L(-1) bulk nifedipine solutions were 98.46+/-0.86% and 98.23+/-0.92%, respectively. A detection limit of 3.42x10(-10) mol L(-1) bulk nifedipine was achieved. The procedure was successfully applied for assay of the drug in tablets and spiked human serum with mean recoveries of 101.95+/-1.42% and 98.70+/-0.63%, respectively. The limit of detection of the drug in spiked human serum was found to be 3.90x10(-10) mol L(-1).     

The dangers of using KBr,KI and CaI2 as mulling agents during the preparation of infrared discs of complexes

Tribochemical reactions of KBr, KI and CaI₂ with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]1/2H₂O (L = formylhydrazine) give novel Cu^I and Cu^II complexes, which have been characterized by elemental analyses, spectral (i.r., u.v.–vis., ¹H-n.m.r.) and magnetic measurements. The i.r. spectra indicate that (L) behaves in a monodentate manner, coordinating via the azomethine nitrogen (C-N) group in the Cu^II complexes, but behaving as a bidentate ligand, via the carbonyl oxygen and NH₂ groups in the Cu^I complexes. KI and CaI₂ react with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]-1/2H₂O in the solid state, accompanied by a colour change, substitution of the chloride by iodide ions, and reduction of Cu^II to Cu^I to give complexes with formulae [Cu(L)I(EtOH)_1/2] and [Cu_1.7(L)I_1.7(EtOH)_1/2]. On the other hand, the tribochemical reaction of KBr with [Cu(L)Cl₂(EtOH)_3/2(H₂O)]1/2H₂O is accompanied by a colour change; substitution of the chloride by bromide ions, but without reduction of Cu^II and yields a complex of formula [Cu(L)₂Br₂(EtOH)(H₂O)]1/2EtOH. The spectral and magnetic results suggest a distorted octahedral geometry for the Cu^II complexes while a tetrahedral geometry around the Cu^I ion. The non-stoichiometric structure of [Cu_1.7(L)I_1.7(EtOH)_1/2] is discussed.     

Studies of Monolayer and Mixed Micelle Formation of Anionic and Nonionic Surfactants in the Presence of Adenosine-5-monophosphate

The interactions between the anionic surfactant di-(2-ethylhexyl) phosphate sodium salt (DEP) and two nonionic surfactants, dimethyldecyl phosphineoxide (DDPO) and dimethyltetradecyl phosphineoxide (DTPO), at the interface and in the micellar phases were investigated in the absence and presence of adenosine-5-monophosphoric acid disodium salt (AMP). The mixed systems were DEP–DDPO, DEP–DDPO/AMP (0.001 mol⋅L⁻¹), DEP–DTPO, and DEP–DTPO/AMP (0.001 mol⋅L⁻¹) at different bulk mole fractions of the anionic component (α ₁=0.9,0.8,0.6,0.4,0.2). The mixed systems studied were investigated based on the theoretical models of Rubingh and Clint. The results showed surface tension reduction efficiency. The adsorbed mixed monolayer demonstrated stronger interactions than the mixed micelles, whereas AMP increased the interfacial interactions more than those in the micellar phase. The Gibbs energy of mixing suggests that the stability of the mixed micellar phase is greater than that of the micellar phases of the individual components. The synergism that occurred in the different mixed phases is discussed.     

Synthesis of Some New 1,2,3,4‐Tetrahydropyrimidine‐2‐thione and Their Thiazolo[3,2‐a]pyrimidine,Thiazino and Benzothiazepine Derivatives

The starting N‐(2‐pyridyl)‐6‐methyl‐4‐phenyl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxamide ( 4 ) was used as a key intermediate for the synthesis of new 1,2,3,4‐tetrahydropyrimidine‐2‐thione and their thiazolo[3,2‐a]pyrimidine, thiazino and benzothiazipen derivatives. The reaction of 4 with haloketones in ethanol catalyzed by base afforded the corresponding thiophenopyrimidine and pyrimidothiazipine derivatives 5 , 6 , 7 , 8 , 9 , 10 . Methylation and formylation of 4 led to the pyrimidine derivatives 15 and 16 , respectively. The preventative compounds were established on the basis of elemental and spectral data.     

1,3,4-Oxadiazole N-Mannich Bases: Synthesis,Antimicrobial, and Anti-Proliferative Activities

The reaction of 5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thione 3 with formaldehyde solution and primary aromatic amines or 1-substituted piperazines, in ethanol at room temperature yielded the corresponding N-Mannich bases 3-arylaminomethyl-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 4a–l or 3-[(4-substituted piperazin-1-yl)methyl]-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 5a–d, respectively. The in vitro inhibitory activity of compounds 4a–l and 5a–d was assessed against pathogenic Gram-positive, Gram-negative bacteria, and the yeast-like pathogenic fungus Candida albicans. The piperazinomethyl derivatives 5c and 5d displayed broad-spectrum antibacterial activities the minimal inhibitory concentration (MIC) 0.5–8 μg/mL) and compounds 4j, 4l, 5a, and 5b showed potent activity against the tested Gram-positive bacteria. In addition, the anti-proliferative activity of the compounds was evaluated against prostate cancer (PC3), human colorectal cancer (HCT-116), human hepatocellular carcinoma (HePG-2), human epithelioid carcinoma (HeLa), and human breast cancer (MCF7) cell lines. The optimum anti-proliferative activity was attained by compounds 4l, 5a, 5c, and 5d.     

Enhancement of β-Glucan Biological Activity Using a Modified Acid-Base Extraction Method from Saccharomyces cerevisiae

Beta glucan (β-glucan) has promising bioactive properties. Consequently, the use of β-glucan as a food additive is favored with the dual-purpose potential of increasing the fiber content of food products and enhancing their health properties. Our aim was to evaluate the biological activity of β-glucan (antimicrobial, antitoxic, immunostimulatory, and anticancer) extracted from Saccharomyces cerevisiae using a modified acid-base extraction method. The results demonstrated that a modified acid-base extraction method gives a higher biological efficacy of β-glucan than in the water extraction method. Using 0.5 mg dry weight of acid-base extracted β-glucan (AB extracted) not only succeeded in removing 100% of aflatoxins, but also had a promising antimicrobial activity against multidrug-resistant bacteria, fungi, and yeast, with minimum inhibitory concentrations (MIC) of 0.39 and 0.19 mg/mL in the case of resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. In addition, AB extract exhibited a positive immunomodulatory effect, mediated through the high induction of TNFα, IL-6, IFN-γ, and IL-2. Moreover, AB extract showed a greater anticancer effect against A549, MDA-MB-232, and HepG-2 cells compared to WI-38 cells, at high concentrations. By studying the cell death mechanism using flow-cytometry, AB extract was shown to induce apoptotic cell death at higher concentrations, as in the case of MDA-MB-231 and HePG-2 cells. In conclusion, the use of a modified AB for β-glucan from Saccharomyces cerevisiae exerted a promising antimicrobial, immunomodulatory efficacy, and anti-cancer potential. Future research should focus on evaluating β-glucan in various biological systems and elucidating the underlying mechanism of action.