Low temperature synthesis and characterization of Mn3O4 nanoparticles

Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn₃O₄ nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements confirm a typical Mn²⁺signal with a highly resolved hyperfine structure.      

Synthesis of Xenbucin using Suzuki reaction catalyzed by Pd/C in water

Xenbucin 1, an analgesic drug, was synthesized in 4 steps using two different routes. The biaryl fragment could successfully be produced via a Pd/C catalysed Suzuki coupling in water using sodium tetraphenylborate as a phenylation reagent. Overall yields of the routes were 36% and 59%, respectively.      

Density functional theory study of the photosensitization mechanisms of indigo

The triplet excited state properties and photosensitization mechanisms of indigo were investigated based on density functional theory calculations. The solvent effects on the photosensitization mechanisms of indigo have also been considered. The thermodynamic feasibility of the possible ¹O₂ and O₂·⁻-photogeneration pathways by triplet excited state indigo in different solvents was explored, in order to gain some deeper insights into the photosensitization characters of the dye.      

<Emphasis Type="Italic">N</Emphasis>-Alkylation of benzimidazoles with ketonic Mannich bases and the reduction of the resulting 1-(3-oxopropyl)benzimidazoles

Benzimidazole, benzimidazoles diversely substituted at position 2, and 5,6-dimethylbenzimidazole have been alkylated at N ¹ with ketonic Mannich bases derived from acetophenones, acetylnaphthalenes, 2-acetylthiophene and 1-tetralone to afford a series of novel 1-(3-oxopropyl)benzimidazoles. The reduction of these transamination products with NaBH₄ in methanol produced the corresponding 1-(3-hydroxypropyl)benzimidazoles in excellent yields.      

High surface area nano-sized La0.6Ca0.4MnO3 perovskite powder prepared by low temperature pyrolysis of a modified citrate gel

Single phase nanocrystalline La_0.6Ca_0.4MnO₃ powder was synthesized by both the usual and a modified citrate gel precursor method, and the effects on the formation of homogeneous nano-sized powder with a perovskite structure were investigated. In the modified method, single phase La_0.6Ca_0.4MnO₃ powder with an average particle size of 17.2 nm was obtained when the powder was pyrolyzed at 520°C for 2 h. Its specific surface area was 40.7 m² g⁻¹, about 4-fold larger than that of powder made by the usual citrate gel method.      

Kinetics of base hydrolysis of α-amino acid esters catalyzed by palladium(II) piperazine complex

The kinetics of base hydrolysis of glycine, histidine, and methionine methyl esters in the presence of [Pd(pip)(H₂O)₂]²⁺ complex, where pip is piperazine, is studied in aqueous solutions, at T = 25°C, and I = 0.1 mol dm⁻³. The rate of ester hydrolysis for glycine methyl ester is studied at different temperature and dioxane/water solutions of different compositions. The kinetic data are fit under the assumption that the hydrolysis proceeds in one step. The activation parameters for the base hydrolysis of the complexes are evaluated      

Synthesis and pharmacological properties of 3-(2-methyl-furan-3-yl)-4-substituted-Δ<Superscript>2</Superscript>-1,2,4-triazoline-5-thiones

By the reaction of 2-methyl-furan-3-carboxylic acid hydrazide with isothiocyanates, 1-[(2-methyl-furan-3-yl)carbonyl]-4-substituted thiosemicarbazides 1 were obtained. Further cyclization with 2% NaOH led to the formation of 3-(2-methyl-furan-3-yl)-4-substituted-Δ²-1,2,4-triazoline-5-thiones 2. The pharmacological effects of 2 on the central nervous system in mice were investigated. Strong antinociceptive properties of the investigated derivatives were observed in a wide range of doses.      

Influence of complexation on the composition of equilibrium phases in the system of Ce2(SO4)3-La2(SO4)3

The cocrystallization of Ce₂(SO₄)₃ and La₂(SO₄)₃ is studied in aqueous and H₂SO₄ (150 g/dm³) solutions at 25 °C and 64 °C. The effect of the formation of inner sphere sulfate complexes of the type LnSO ₄ ⁺ in determining the composition of the equilibrium phases is revealed.      

Preliminary results of a quick,simple method of detecting antimony in water samples

Preliminary results of development of a direct and fast method of determination of antimony in samples of tap water using GFAAS are presented. The found levels of antimony were lower than permitted for human consumption. A mixture of Pd and Mg(NO₃)₂ (concentrations in the injected solution: 8.6 μg mL⁻¹ and 5.8 μg mL⁻¹ respectively) was used as the chemical modifier. The pyrolysis and atomization temperatures were 1000 and 1700°C, respectively and the mean analytical recovery 98.2%.      

A novel redox-active calix[4]arene-tetrathiafulvalene dyad

A novel redox-active calix[4]arene-TTF 5 was prepared by the reaction of p-tert-butylcalix[4]arene 4 with the tosylated TTF 3 in the presence of cesium fluoride. The structure of the dyad 5 was identified by X-ray diffraction analysis, and the preliminary electrochemical properties of 5 were investigated by cyclic voltammetry (CV), for which two reversible one-electron waves were observed. Moreover, the UV-vis absorption spectra studies show that the dyad 5 undergoes progressive oxidation at the TTF moiety in presence of increasing amounts of Cu²⁺ or Hg²⁺.      

Methylcellulose/SiO<Subscript>2</Subscript> hybrids: sol-gel preparation and characterization by XRD,FTIR and AFM

Methylcellulose (MC) / SiO₂ organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO₂. AFM depicts surface roughness which depends on the silica precursor and MC content.      

Intramolecular N to N acyl migration in conformationally mobile 1′-acyl-1-benzyl-3′,4′-dihydro-1′<Emphasis Type="Italic">H</Emphasis>-spiro[piperidine-4,2′-quinoline] systems promoted by debenzylation conditions (HCOONH<Subscript>4</Subscript>/Pd/C)

We report an efficient and useful synthesis of new attractive spiropiperdine scaffolds 4 based on an intramolecular acyl transfer process in 1′-acyl-1-benzyl-3′,4′-dihydro-1′H-spiro[piperidine-4,2′-quinolines] 3 using simple and mild debenzylation reaction conditions (HCOONH₄/Pd/C). The compounds 3 were prepared by acylating 1-benzyl-4′-methyl-3′,4′-dihydro-1′H-spiro[piperidine-4,2′-quinolines] 2 that are easily available from 1-benzyl-4-piperidone 1. The intramolecular character of this process was proven primarily through a crossover experiment technique. Through an examination of all spectroscopic information (¹H, ¹³C NMR, VT-¹H NMR, and ²D NMR) it was possible to correctly predict amide configurations and piperidine ring conformations of starting and final spiropiperidine compounds.      

A hydroxyaminophosphane derived from 2-imidazolidone and its unusual structure in solution

A novel hydroxyamino phosphane was synthesised through the reaction of 2-imidazolidinone with ClPPh2 and subsequently reaction of the resulting bisphosphino derivative with the Grignard reagent BrMgC₅H₁₁. The interaction of the pentyl substituent with one of the two phosphino groups and the structure in solution is shown by multinuclear NMR-spectroscopy..      

The interaction of [Pd(N,N-dimethylaminopropylamine)(H2O)]2+ with dicarboxylic acids and inosine: Thermodynamic model for carboplatin drug

The Pd(DMPA)Cl₂ complex, where DMPA = N,N-dimethylaminoproylamine, was synthesized and characterized. The stoichiometry and stability constants of the complexes formed between various dicarboxylic acids and [Pd(DMPA)(H₂O)₂]²⁺ were investigated. The effect of solvent dielectric constant, chloride ion concentration of the medium and temperature on the stability constant of the cyclobutanedicaroxylic acid (CBDCA) complex was investigated. The equilibrium constants for the displacement of coordinated CBDCA by inosine, taken as an example of DNA constituents, were calculated. The results are expected to contribute to the chemistry of antitumour agents.      

New 1H-1-alkyl-6-methyl-3-phenyl-7-phenylazo-pyrazolo[5,1-c][1,2,4]triazoles through regioselective alkylation of 1H-6-methyl-3-phenyl-7-phenylazopyrazolo[5,1-c][1,2,4]triazoles

1H-1-Alkyl-6-methyl-3-phenyl-7-phenylazopyrazolo[5,1-c][1,2,4]triazoles (2aa-ad) were obtained by regioselective alkylation of 1H-6-methyl-3-phenyl-7-phenylazopyrazolo[5,1-c][1,2,4]triazoles (2a). 1H-1-Alkyl-6-methyl-3-phenyl-7-phenylazopyrazolo[5,1-c][1,2,4]triazoles 2aa and 2ab were also prepared by coupling phenyldiazonium chloride with 1H-1-alkyl-6-methyl-3-phenyl-pyrazolo[5,1-c][1,2,4]triazoles 1aa and 1ab. The new compounds were characterized by IR, UV-VIS, ¹H-NMR, ¹³C-NMR, and ¹⁵N-NMR spectroscopy and their structures and actual tautomeric forms were established unequivocally.      

The effect of substituents of immobilized Rh complexes on the asymmetric hydrogenation of acetophenone derivatives

Using a modified Augustine’s method variously substituted Rh complexes were anchored on Al₂O₃ support. The prepared catalysts were characterized by spectroscopic methods and were applied in the hydrogenation of several acetophenone derivatives (p-CF₃-acetophenone, acetophenone, p-NH₂-acetophenone). Enantioselective C=O hydrogenations were observed with reasonable activity and selectivity on all heterogenized complexes, e.e. up to 80%. At the same time the immobilized samples showed the advantages of the heterogeneous systems: easy handling and recyclability.      

Chiral enantiopure bis(thio)ureas derived from TADDOL and their carboxylate complexation capacity

New chiral enantiopure ureas and thioureas with (R,R)-TADDOL backbone were synthesized. Bis-(thio)ureas with C2 symmetry were obtained from TADDOL iso(thio)cyanates and bifunctional amino-(thio)ureas from TADDAMINE, respectively. These were tested for carboxylate recognition capacity and the association constant was determined for the most stable complex.      

Comparison of structure,log<Emphasis Type="Italic">P</Emphasis> and P388 cytotoxicity of some phenyl and ferrocenyl cyclic chalcone analogues. Application of RP-TLC for log<Emphasis Type="Italic">P</Emphasis> determination of the ferrocenyl analogues

Cyclic chalcone analogues (2–5) and their ferrocenyl counterparts (6–10) were synthesized and their logP and P388 cyctotoxity were investigated. The structures of the newly synthesized compounds were confirmed by IR ¹H and ¹³NMR spectroscopy. Comparison of conjugation and stereochemistry of the respective derivatives showed similar characteristics compared to ones with some higher degree of conjugation in the ferrocenyl series. Comparison of logP of the ferrocenyl derivatives determined by a validated RP-TLC method showed the ferrocenyl derivatives to have higher logP _TLC. The results demonstrate that the differences in three dimensional shape, conjugation and lipophilicity do not have strong influence on the P388 cytotoxicity of the investigated phenyl (1−5) and ferrocenyl (6−10) enones.      

Macrocyclic host cyclophosphazenes from aminolysis of N3P3CI6 by bis-(2-ortho-aminophenoxyethyl)ether

Aminolysis of N₃P₃CI₆ by an oxodiamine, bis-(2-ortho-aminophenoxyethyl) ether, has been carried out under various experimental conditions and new products with different architectures have been obtained. The reaction in diethyl ether when using a Na₂CO₃-water interface process gives the mono-BINO as major product. Reaction on Al₂O₃/KOH leads to the spirocyclic compound, while, when the reaction is carried out in toluene in the presence of NEt₃, a mixture of mono- and di-BINO products are obtained. These new products have been characterized by IR, ¹H and ³¹P NMR spectroscopy.      

ZrOCl<Subscript>2</Subscript> · 8H<Subscript>2</Subscript>O: An efficient catalyst for rapid one-pot synthesis of 3-carboxycoumarins under ultrasound irradiation in water

In this report, a rapid, efficient and environmental friendly synthesis of 3-carboxycoumarins under ultrasound irradiation in water media is described. The Knoevenagel condensation of Meldrum’s acid with substituted benzaldehydes in the presence of zirconium oxide chloride (ZrOCl₂·8H₂O) and ultrasonic irradiation in water gave the corresponding 3-carboxycoumarins in good to excellent yields.