On the Synthesis of Some 2-Arylhydrazono-3-oxothieno[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridines by Reaction of Nitrilimines with 2-Mercaptonicotinic Acid

Summary. Nitrilimines prepared from N-arylhydrazono chlorides reacted with 2-mercaptonicotinic acid yielding the corresponding addition products, 2-[(2-oxo-1-arylhydrazonopropan-1-yl)mercapto] nicotinic acids, which were treated with 1,1-carbonyldiimidazole in THF affording by cyclocondensation the corresponding hitherto unknown 2-arylhydrazono-3-oxothieno[2,3-b]pyridines.     

Preparation and Properties of Aramid-Silica Hybrids with Inter-Phase Bonding Through (3-glycidoxypropyl)-trimethoxysilane

Nano-composites from aramid-silica system have been prepared via sol-gel process. Poly (phenyleneterephthalamide) copolymer chains were prepared by reacting a mixture of p- and m-phenylenediamines with terephthaloyl chloride in dimethylacetamide used as solvent. The sol-gel process in the polymer matrix was carried out through hydrolysis and condensation of a mixture of tetraethoxysilane and (3-glycidoxypropyl) trimethoxysilane. The latter was used to develop linkage, on one hand with silica network structure using alkoxy groups and on the other hand with aramid chains at its secondary amine groups through glycidal groups of silane. Mutual interaction between the two disparate phases aramid and silica network was thus created. Thin films of the composites containing different proportions of silica ranging from 5.0 to 25.0-wt% were cast by the solvent elution technique. The α-relaxation temperature associated with the glass transition was measured by the dynamic mechanical thermal analysis. The results showed an increase in the glass transition temperature from 328°C for the pure aramid to 352°C for the hybrid materials containing 25-wt% silica, an indicative of the increased interfacial interaction between the two phases. Films having relatively low silica content were flexible and transparent, but those with high silica content were opaque and brittle. These films were tested for their tensile strength, modulus and toughness. The mechanical strength of the composites as compared to the pure aramid increased initially but with further addition of silica the strength decreased. The initial increase can be explained due to increased interfacial interaction between the two phases, however agglomeration of silica particles was responsible for decreasing strength at higher silica contents.     

Preparation and Characterisation of Meloxicam Hydroxy Propyl <Emphasis Type="Italic">β</Emphasis>-Cyclodextrin Inclusion Complex

Meloxicam is a non steroidal anti inflammatory drug, used in the treatment of rheumatoid and osteoarthiritis. It is practically insoluble in water and its prolonged use is associated with the incidence of side effects like gastro intestinal perforations, ulcerations and bleeding. Therefore, an attempt has been made to improve the aqueous solubility of the drug by making an inclusion complex using hydroxy propyl β cyclodextrin(HPβ-CD). The complexes were prepared by physical mixture and freeze drying method. The different methods employed for evaluation such as DSC, XRD, SEM and FT-IR studies indicated complete formation of the complex by freeze drying method in a molar ratio of 1:2. The prepared complexes showed improved in-vitro dissolution profile as compared to the pure drug.     

The effect of humidity on thermal process of zinc acetate

The thermal decomposition of zinc acetate dihydrate Zn(CH₃CO₂)₂·2H₂O in some humidity-controlled atmospheres has been successfully investigated by novel thermal analyses, which are sample-controlled thermogravimetry (SCTG), thermogravimety combined with evolved gas analysis using mass spectrometry (TG–MS) and simultaneous measurement of differential scanning calorimetry and X-ray diffractometry (XRD–DSC). The thermal processes of anhydrous zinc acetate in dry gas atmosphere by conventional linear heating experiment initiated with the sublimation around 180 °C, followed by the fusion and the decomposition over 250 °C. SCTG was useful to interpret clearly the successive reaction because the high-temperature parallel decompositions were effectively inhibited. The thermal behavior changed dramatically by introducing water vapor in the atmosphere and the thermal process was quite different from that in dry gas atmosphere. Zinc oxide (ZnO) was formed only in a humidity-controlled atmosphere, and could be easily synthesized at temperatures below 300 °C. XRD–DSC equipped with a humidity generator revealed directly the crystalline change from Zn(CH₃CO₂)₂ to ZnO. A detailed thermal process of Zn(CH₃CO₂)₂·2H₂O and the effect of water vapor are discussed.     

Polyol-Metall-Komplexe. 25. rac-Mannose,rac-Arabit und L-Threit als deprotonierte Liganden in Ferraten(III)

Polyol Metal Complexes. 25. rac-Mannose, rac-Arabitol and L -Threitol as Deprotonated Ligands in Ferrates(III ) Ba₂[Fe₂(β-rac-ManfH_?5)₂] · 12H₂O ( 1 ), Sr₄[Fe₄(rac-Arab1,2,3,5H_?4)₄(OH)₂]CO₃ · 33 H₂O ( 2 ), and Ba₂[Fe₂(L-ThreH_?4)₂(OH)₂] · 12.5 H₂O ( 3 ) (Man = mannose, Arab = arabitol, Thre = threitol) have been crystallized from alkaline aqueous solution. Crystal structure analysis revealed dinuclear ferrate(III ) ions for 1 and 3 , the former being a C_i-symmetrical homoleptic ferric complex with pentadentate pentaanions derived from racemic β-mannofuranose. In 3 , besides tetradentate L -threitolato ligands, there is one terminal hydroxo ligand at each ferric center. Hydroxo ligands are also present in the C_i-symmetrical hexaanions of 2 , which are tetranuclear planar entities built up from four edge-sharing FeO₆ octahedra. However arabitol is a pentitol, the tetraanionic ligands are only tetradentate for steric reasons.     

Studies on Amidothiosemicarbazides and Related Hcterocyclic Derivatives ( XIII) --Synthetic Studies on 2-(3-Pyridyl)-5-Arylamino- 1,3, 4-Thiadiazoles and Oxadiazoles

By ring-closure of 1-nicotinyl-4-arylthiosemicarbazides under the catalysis of concentrated sulfuric acid or mercuric acetate, a series of 2-(3-pyridyl)-5-arylarnino-1,3,4-thiadiazoles and 2-(3-pyridyl)-5-ary-lamino-1,3,4-oxadiazoles were synthesized, respectively. All the products were subjected to testing of biological activity. Furthermore, the IR, 1H NMR and MS spectral properties of these new compounds were studied in details and some significant conclusions were drawn.     

Amperometric Determination of lndole-3-acetic Acid Based on Platinum Nanowires and Carbon Nanotubes

Platinum nanowire （PtNW） can be grown by electrodeposition in polycarbonate membrane, with the average diameter of the nanowires about 250 nm. The PtNW and multiwalled carbon nanotubes （CNT） are then dispersed into chitosan （CHIT） solution. The resulting PtNW-CNT-CHIT material brings new capabilities for electrochemical devices by using the synergistic action of the electrocatalytic activity of PtNW and CNT. By dropping the PtNW-CNT-CHIT film onto the glassy carbon （GO） electrode surface, and after evaporation an amperometric sensor for the determination of indole-3-acetic acid （IAA） was developed. The oxidation current of IAA increased significantly at the PtNW-CNT-CHIT film coated GC electrode, in contrast to that at the CNT-CHIT modified GC. The linear response of the sensor is from 50 ng/ml to 50 μg/ml with a detection limit of 25 ng/mL.     

Photocleavage studies of fluorescent amino acid conjugates bearing different types of linkages

The synthesis and photochemistry of 3-oxo-3H-benzopyran derivatives linked through ester, anhydride, urethane and carbonate bonds to representative l-amino acids, at the amino and carboxylic acid groups at the main chain or the hydroxyl group at the side chain, were carried out. The stability to photolysis of the resulting conjugates was studied at different wavelengths of irradiation (254, 300 and 350 nm), the anhydride and ester linkages being the most sensitive in the studied conditions.     

含1,3-亚丙基冠醚的合成

为了进一步研究亚丙基冠醚的络合行为,合成了三种含1,3-亚丙基冠醚,即2,3-苯并-1,4,7,11-四氧-环十三-2-烯(苯并-13-冠-4)(1)、2,3-苯并-1,4,8,11,14-五氧-环十七-2-烯(苯并-17-冠-5)(2)、2,3-苯并-1,4,7,10,14,17-六氧-环十九-2-烯(苯并-19-冠-6)(3)。通过元素分析、红外光谱、质谱、核磁共振谱和 X-衍射晶体结构分析,确证了它们的结构。