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 .     

Phosphorated calix[6]arene derivatives as an ionophore for atropine-selective membrane electrodes

37,40-bis-[(diethoxy-thiophosphoryl)oxy]-5,11,17, 23,29,35-hexakis(1,1 -dimethyl-ethyl)-calix[6]arene-8,39,41,42-tetrol; 37,38,39,40,41-pentakis-(di-ethoxythiophosphoryl)-oxy]-5,11,17,23,29,35-hexakis (1,1-dimethylethyl)-calix[6]-arene-42-ol; and 37-[(diethoxythiophosphoryl)oxy]-5,11,17,23,29,35-hexakis-(1,1dimethylethyl)-calix[6]arene-38,39,40, 41,42-pentol were introduced as neutral ionophores for atropine-selective electrodes. Practical Nernstian responses were found (54.3, 49.1, and 50.8 mV/decade) for polyvinyl chloride membrane electrodes incorporating these compounds. They exhibited practical linear ranges of 1.9 x 10(-6)-7.9 x 10(-3), 7.9 x 10(-6)-7.9 x 10(-3), and 6.3 x 10(-6)-7.9 x 10(-3) M, respectively. The optimum pH range was 2.5-8.5. The selectivity coefficient values were estimated and interpreted. The electrode performance was correlated to the calixarene structure. Then, the electrode was applied to an actual analysis of pharmaceutical atropine preparations. The recovery values of 18.7 microg/mL-5.5193 mg/mL atropine sulfate were 97.5-99.1%. The corresponding relative standard deviation values ranged between 0.39-0.72% for 5 determinations. The first electrode was applied successfully for analyzing atropine sulfate in injection solution and eye drops.     

Preparation and characterization of new photosensitive and optically active poly(amide-imide)s from N-trimellitylimido-L-amino acid and dibenzalacetone moiety in the main chain

Six new photosensitive and optically active poly(amide-imide)s 8a–8f with good inherent viscosities based on dibenzalacetone moiety were synthesized from the direct polycondensation reaction of N-Trimellitylimido-L-amino acids 3a–3f with 2,5-bis(4-aminobenzylidene)cyclopentanone 7 by two different methods such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone/triphenyl phosphite/calcium chloride/pyridine and direct polycondensation in a tosyl chloride/pyridine (py)/N,N-dimethylformamide system. Diamine 7 was synthesized by using a two-step reaction. At first 2,5-bis(4-nitrobenzylidene)cyclopentanone 6 was prepared from the reaction of two equimolars 4-nitrobenzaldehyde 5 and one equimolar cyclopentanone 4 and dinitro compound 6 was reduced by using Na2S. Also N-trimellitylimido-L-amino acids 3a–3f were synthesized by the condensation reaction of trimellitic anhydride 1 with two equimolars of various L-amino acids 2a–2f in an acetic acid solution. The polymerization reactions produced a series of photosensitive and optically active poly(amide-imide)s with high yield and good inherent viscosity. The resulted polymers were fully characterized by means of FTIR and ¹H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests, UV-VIS spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and derivative of thermogravimetric. These macromolecules exhibited maximum UV-VIS absorption at around 395 and 265 nm in a N,N-dimethylformamide solution.     

Energy of unitary Cayley graphs and gcd-graphs

This work is based on ideas of Ili? [A. Ili?, The energy of unitary Cayley graphs, Linear Algebra Appl. 431 (2009) 1881-1889] on the energy of unitary Cayley graph. For a finite commutative ring R with unity , the unitary Cayley graph of R is the Cayley graph whose vertex set is R and the edge set is {{a,b}:a,b∈Randa-b∈R^×}, where R^× is the group of units of R. We study the eigenvalues of the unitary Cayley graph of a finite commutative ring and some gcd-graphs and compute their energy. Moreover, we obtain the energy for the complement of unitary Cayley graphs.     

A Facile Synthesis of Bridged Polycyclic Naphthooxazocine Skeletons: Eight‐Membered‐Ring Constructions via Tandem Dinucleophilic Addition of Naphthalenols to Quinolinium Salts

The efficient synthesis of bridged polycyclic naphthooxazocines 3 via addition of naphthalenols 1 as a bis‐nucleophile to N‐alkylquinolinium salts 2 is described (Scheme 1 and Table 2). This new approach provides a powerful entry into polycyclic structures containing bicyclic N,O‐acetals related to bioactive compounds.     

Organic Reaction in Water: A Highly Efficient and Environmentally Friendly Synthesis of Spiro Compounds Catalyzed by L‐Proline

We have developed a clean, simple and efficient method for the synthesis of spiro compounds by three‐component reaction of isatins (=1H‐indole‐2,3‐diones) or acenaphthylene‐1,2‐dione, 1,3‐diphenyl‐1H‐pyrazoles‐5‐amines, and tetronic acid (=furan‐2,4‐(3H,5H)‐dione or 2‐hydroxy‐1,4‐naphthoquinone in the presence of a catalytic amount of L ‐proline in aqueous media. The advantages of this procedure are mild reaction conditions, high yields of products, operational simplicity, and easy workup procedures employed.     

P NMR study of the stoichiometry, stability and thermodynamics of new complexation between uranyl (II) nitrate and N-methyliminobis(methylenephosphonic acid) in two binary D2O-DMSO-d6 solvent mixtures

The complexation reaction between uranyl (II) nitrate, and N-methyliminobis(methylenephosphonic acid) (MIDPH) was investigated in two different binary solvent mixtures of D₂O-DMSO-d₆ at various temperatures using ³¹P NMR spectroscopy. The exchange between the free ligand and the 1:1 complexed ligand was slow on the NMR timescale and two ³¹P NMR signals were observed. The formation constant of the resulting complex was evaluated from integration of the two ³¹P NMR signals. The values of thermodynamic parameters of the resulting complex (ΔH, ΔS and ΔG) were determined from the temperature dependence of the formation constants. In the two solvent mixtures studied, the resulting complex is enthalpy stabilized but entropy destabilized.     

An innovative electrochemical approach for voltammetric determination of levodopa using gold nanoparticles doped on titanium dioxide nanotubes

Catalytic nanotubes made from titanium dioxide (TiO₂-NTs) and covered with gold nanoparticles (Au-NPs) were prepared via galvanic deposition of the Au-NPs on the TiO₂-NTs. The morphology and surface characteristics of the resulting electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicated that the Au-NPs were homogeneously deposited on the surface of TiO₂-NTs which consist of individual tubes of about 40?C80?nm in diameter. The AuNPs with a size of 80?C100?nm are well-dispersed on the surface of the TiO₂-NTs. The electro-catalytic activity of the electrodes towards the electro-oxidation of levodopa was studied by cyclic voltammetry, differential puls voltammetry. The results showed that the electrodes exhibit a considerably higher activity toward the oxidation of levodopa. The oxidation peak current linearly depends on the concentration of levodopa in the 10 to 70???M concentration range. Levodopa was determined by the method in pharmaceutical preparations, and results were found to be satisfactory.