Electrical conductivity, electronic absorption, IR and NMR studies on some ethyl cyanoacetate phenylhydrazones and their lanthanide complexes

The electrical conductivities and the electronic, IR and NMR spectra were measured for some ethyl cyanoacetate phenylhydrazone derivatives and their lanthanide complexes in the temperature range 20–200?C. Semiconducting behaviour was detected for these systems (positive dσ/dT). A correlation was established between the electrical properties and the structures of the free ligand molecules and their complexes. The mechanism of the conduction process was evaluated. The electronic absorption spectra in ethanol were measured and are discussed. Elemental analyses were performed and the IR and NMR spectra (of the diamagnetic complexes) were measured to throw more light on the structures of these complexes.     

Thermal stability of di-μ-oxo-bridged binuclear and tetranuclear manganese(IV) complexes

Summary The thermal stabilities of the [(di--oxo)Mn₂] cores of bi- and tetranuclear Mn^IV complexes have been studied. The stabilities are discussed in terms of structural and conformational factors. The energies of activation (E_a) of the decomposition reactions were determined. The nature of interaction of the solvent of crystallization is also discussed.     

Spectrophotometric microdetermination of uranium with m- and p-carboxyphenylazo-chromotropic acid

Summary A simple and rapid method for the spectrophotometric determination of uranium usingm- andp-carboxyphenylazo-chromotropic acid is given. The optimum conditions favouring the formation of the two complexes are reported. The molecular structure was found to be 1 1 and 1 2 of uranium to them- or thep-compound. Beer's law is obeyed for the ranges 2–16 and 2–18 ppm of uranium in the case of them- andp- compound respectively.

---

Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Uran mit Hilfe vonm-bzw.p-Carboxyphenylazochromotropsäure wurde beschrieben. Die besten Arbeitsbedingungen für die Bildung der beiden Komplexe wurden angegeben. Die Zusammensetzung entspricht dem Verhältnis 1 1 bzw. 1 2 von Uran zurm-bzw. zurp-Verbindung. Das Beer'sche Gesetz ist für die Bereiche 2–16 bzw. 2–18 ppm Uran im Falle derm-bzw. derp- Verbindung erfüllt.

     

Uptake of curcumin by supported metal oxides (CaO and MgO) mesoporous silica materials

A series of LaMnO₃ perovskites as catalysts for selective reduction of NO by CO were synthesized using microwave and ultrasound assisted sol-gel method. The catalysts were characterized by BET area measurements, Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) techniques. XRD results showed revealed the orthorhobic crystalline structure and with very high purity. SEM analyses proved lower particle size for ultrasound (US) assisted synthesized LaMnO₃. In addition, US assisted synthesized LaMnO₃ presented higher surface area respect to other catalysts, synthesized by the other methods. Results revealed that the ultrasound assisted synthesized catalyst determines the lowest crystallite size, the highest surface area and the highest concentration of O-vacancies and, as a consequence, the highest catalytic activity.

Open image in new window

     

A diastereoselective synthesis of functionalized bis-spirorhodanine-linked cyclopentanes via C(sp3)–H activation

A diastereoselective synthesis of bis-spirorhodanine-linked cyclopentane derivatives via the [2 + 2+1] cycloaddition reaction between alkyl (Z)-2-(3-alkyl-4-oxo-2-thioxothiazolidin-5-ylidene)acetates (alkylidenerhodanines) and azomethine ylides, prepared in situ from iodine mediated reaction of 2-methylquinoline and pyridine in the presence of base, has been developed. The structure of a typical product was confirmed by X-ray crystallography.     

Synthesis and in vitro evaluation of novel tetralin-pyrazolo[3,4-b]pyridine hybrids as potential anticancer agents

New hybrids of tetralin-pyrazolo[3,4-b]pyridine were synthesized in good yields. The structures of newly synthesized compounds were confirmed by IR, NMR, MS, and elemental analyses. Some of the new compounds were in vitro evaluated as antiproliferative candidates against two human cancer cell lines (HCT116 and MCF-7). Most of the examined derivatives showed promising anticancer activity.     

Tetracationic Bis-Triarylborane 1,3-Butadiyne as a Combined Fluorimetric and Raman Probe for Simultaneous and Selective Sensing of Various DNA,RNA, and Proteins

A bis-triarylborane tetracation (4-Ar₂B-3,5-Me₂C₆H₂)-C≡C−C≡C-(3,5-Me₂C₆H₂-4-BAr₂ [Ar=(2,6-Me₂-4-NMe₃-C₆H₂)⁺] ( 2⁴⁺ ) shows distinctly different behaviour in its fluorimetric response than that of our recently published bis-triarylborane 5-(4-Ar₂B-3,5-Me₂C₆H₂)-2,2′-(C₄H₂S)₂–5′-(3,5-Me₂C₆H₂-4-BAr₂) ( 3⁴⁺ ). Single-crystal X-ray diffraction data on the neutral bis-triarylborane precursor 2 N confirm its rod-like dumbbell structure, which is shown to be important for DNA/RNA targeting and also for BSA protein binding. Fluorimetric titrations with DNA/RNA/BSA revealed the very strong affinity of 2⁴⁺ and indicated the importance of the properties of the linker connecting the two triarylboranes. Using the butadiyne rather than a bithiophene linker resulted in an opposite emission effect (quenching vs. enhancement), and 2⁴⁺ bound to BSA 100 times stronger than 3⁴⁺ . Moreover, 2⁴⁺ interacted strongly with ss-RNA, and circular dichroism (CD) results suggest ss-RNA chain-wrapping around the rod-like bis-triarylborane dumbbell structure like a thread around a spindle, a very unusual mode of binding of ss-RNA with small molecules. Furthermore, 2⁴⁺ yielded strong Raman/SERS signals, allowing DNA or protein detection at ca. 10 nm concentrations. The above observations, combined with low cytotoxicity, efficient human cell uptake and organelle-selective accumulation make such compounds intriguing novel lead structures for bio-oriented, dual fluorescence/Raman-based applications.     

Flow injection analysis with tubular membrane ion-selective electrode and coated wires for buspirone hydrochloride

New Plastic membrane ion-selective electrode for buspirone hydrochloride based on buspironium tetraphenylborate was prepared. The electrode exhibited mean slope of calibration graph of 58.4 mV per decade of BusCl concentration at 25 degrees C. The electrode can be used within the concentration range 6.3 x 10(-5) - 10(-2) M BusCl at a pH range of 2.5-7.0. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal temperature coefficient of the electrode, amounting to 0.00056 V degrees C(-1). The electrode showed a very good selectivity for BusCl with respect to a number of inorganic cations, sugars and amino acids. The electrode was applied to the potentiometric determination of the buspirone ion and its pharmaceutical preparation under batch and flow injection conditions. Also, buspirone was determined by conductimetric titrations. Graphite rod, copper and silver coated wire electrodes were prepared and characterized as sensors for the drug under investigation.     

Synthetic approaches towards the sulfonamide substituted‐4,5‐diaryl‐4H‐1,2,4‐triazole‐3‐thiones

A new series of 3‐alkylthio‐4,5‐diaryl‐4H‐1,2,4‐triazoles having a SO₂NH₂ substituent in the para‐position on one of the aryl rings ( 19/25 ) were prepared starting from the appropriate benzoic acid hydrazides ( 15/21 ). Reaction of the corresponding hydrazides with the appropriate isothiocyanates yielded 16/22 , which were cyclized in basic media to give 4,5‐diaryl‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thiones 17/23 . Alkylation of 17/23 afforded the alkylthio compounds 18/24 . Final debenzylation was achieved with concentrated sulfuric acid to give the target sulfonamides 19/25 .