Studies on 1,10-Phenanthroline Complexes of Some Hydroxyaryltellurium Trihalides

The synthesis and structural features of some newly synthesized 1,10-phenanthroline complexes of p-hydroxyphenyl-and 3-methyl-4-hydroxyphenyltellurium trihalides (chlorides, bromides, and iodides) are reported. The resulting complexes have been subjected to elemental analyses, conductance and cryoscopic measurements, infra-red and proton magnetic resonance spectral studies. Solution studies reveal the weak to 1:1 electrolyte type behavior of these complexes in solution. Spectral studies indicate the linkage of phenanthroline to the tellurium atom through the nitrogen atoms. Central tellurium atom in these complexes is hexa-coordinated in an octahedral way.     

Synthesis of New Benzosubstituted Dioxaphosphonines Containing Quinoxaline Subunit

A simple and efficient synthesis of previously unknown benzosubstituted dioxaphosphonines containing a quinoxaline subunit is described. Reasonably good yields of the products, mild reaction conditions, and convenient work-up are the advantages of this method. The procedure does not require any catalyst or activator and can be efficiently achieved via dianion cyclization. All the synthesized compounds have been characterized by satisfactory elemental analyses and spectral (IR, ¹H, ¹³C, ³¹P NMR, and mass) studies.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Characterization of Poly[N-Vinyl-2-Pyrrolidone-Polyethylene Glycol Diacrylate] Copolymeric Hydrogels for Drug Delivery

Abstract

Novel polymeric biodegradable and biocompatible copolymeric hydrogels based on N-vinyl-2-pyrrolidone (NVP) and polyethylene glycol diacrylate (PAC) were designed and synthesized. PAC macromonomer was synthesized by a modified procedure and characterized. Poly[N-vinyl-2-pyrrolidone-polyethylene glycol diacrylate] (Poly[NVP-PAC]) hydrogels were synthesized by varying the concentration of PAC. Azobisisobutyronitrile (AIBN) was used as the free radical initiator and N,N¹-methylene bis(acryl-amide) (BIS) was employed as the crosslinking agent. These hydrogels were characterized by various spectroscopic techniques. Fourier transform-infrared spectroscopy (FT-IR) confirms the formation of copolymer. Thermogravimetric analysis (TGA) curves obtained were continuous indicating the formation of copolymer. The glass transition temperature (T_g) of the copolymer was measured using differential scanning calorimetry (DSC). The equilibrium swelling measurements were carried out in simulated gastric and intestinal fluids (SGF & SIF). These swelling studies indicated that these gels had a higher sorption capacity in SIF when compared to that in SGF. 5-Fuorouracil (5-FU), an anti-cancer drug was entrapped in these hydrogels and the in-vitro release profiles were established in a sequential manner in SGF and SIF. About 50–56% of the drug entrapped was released in a period of 10 days.     

An in silico expert system for the identification of eye irritants

This report describes development of an in silico, expert rule-based method for the classification of chemicals into irritants or non-irritants to eye, as defined by the Draize test. This method was developed to screen data-poor cosmetic ingredient chemicals for eye irritancy potential, which is based upon exclusion rules of five physicochemical properties – molecular weight (MW), hydrophobicity (log P), number of hydrogen bond donors (HBD), number of hydrogen bond acceptors (HBA) and polarizability (Pol). These rules were developed using the ADMET Predictor software and a dataset of 917 eye irritant chemicals. The dataset was divided into 826 (90%) chemicals used for training set and 91 (10%) chemicals used for external validation set (every 10th chemical sorted by molecular weight). The sensitivity of these rules for the training and validation sets was 72.3% and 71.4%, respectively. These rules were also validated for their specificity using an external validation set of 2011 non-irritant chemicals to the eye. The specificity for this validation set was revealed as 77.3%. This method facilitates rapid screening and prioritization of data poor chemicals that are unlikely to be tested for eye irritancy in the Draize test.     

Thermal studies of hypervalent iodine reagents

The use of unconventional synthesis methods in the formation of CaO·2Al₂O₃ (CA₂) is justified because it reduces the formation temperature of the compound. CA₂ is formed by classical method at temperatures above 1,400 °C. The polymeric precursor method allows a significant temperature decrease in CA₂ synthesis reaching temperatures of 1,000 °C. This paper deals with CA₂ synthesis by “citrate” method which is often presented as Pechini method, starting from a mixture of citric acid, ethylene glycol and calcium, and aluminum nitrates. A method based on the formation of a polymeric precursor was also used, starting from a mixture of acrylic acid and nitrates of calcium and aluminum. The results showed a net difference in favor of samples obtained from acrylic acid, which by annealing at 800 °C for 1 h, contain pure CA₂. The samples obtained from citric acid, after annealing at 800 °C are amorphous. After annealing at 900 °C in all samples CA₂ is single phase.     

Acid‐induced homogenous liquid‐phase microextraction: Application of medium‐chain carboxylic acid as extraction phase

In this research, a novel homogeneous liquid‐phase microextraction method was successfully developed based on applying octanoic acid as low‐density extraction solvent. The method was applied for extraction and determination of chlorophenols (CPs) as model compounds. Twelve milliliter of the sample solution was poured into a home‐designed glass vial. Sixty microliter of octanoic acid was solved in water sample by adjusting pH and ionic strength. By rapid addition of 75 μL of concentrated HCl (6 M), a cloudy solution was obtained. Phase separation occurred at 5000 rpm for 5 min. After that, 20 μL of the collected phase (approximately 26 μL) was injected into the HPLC‐UV instrument for analysis. The effect of some parameters such as the volume of concentrated HCl (phase separation reagent), ionic strength, extraction time, centrifugation time, and the volume of extracting phase on the extraction efficiency of the CPs were investigated and optimized. The preconcentration factors in a range of 159–218 were obtained under the optimal conditions. The linear range, detection limits (S/N = 3), and precision (n = 3) were 1– 200, 0.3–0.5 μg/L, and 4.6–5.1%, respectively. Tap water, seawater, and river water samples were successfully analyzed for the existence of CPs using the proposed method and satisfactory results were obtained.     

Synthesis of five-membered N-heterocycles using silver metal

The heterocyclic chemistry field has been revolutionized using transition metal catalyst in recent years. Various research groups have focused on the development of general protocols to achieve better functional group compatibilities and greater levels of molecular complexity under mild reaction conditions using easily available starting substrates. These methods afford many advantages as compared to alternative pathways involved in the synthesis of heterocyclic compounds. In this review article, we have concentrated on the synthesis of nitrogen-containing five-membered heterocylces in the presence of silver catalyst.     

Carrier facilitated transport of thorium from HCl medium using Cyanex 923 in n-dodecane containing supported liquid membrane

Present studies deal with supported liquid membrane (SLM) technique for the separation of thorium from hydrochloric acid (HCl) medium using Cyanex 923 as a carrier. Effects of feed acidity, strippant, and membrane pore size and membrane thickness on the transport of thorium have been studied in detail. The optimized parameters were applied for separation of thorium from a radioanalytical waste. Stability of the membrane and membrane support was investigated. Transport of thorium increased from 78.3 to about 93.7 % with increase in acidity from 0.5 to 2 M using 0.3 M Cyanex 923 in n-dodecane as carrier and 2 M ammonium carbonate as stripping phase. The transport of thorium decreased above 2 M HCl. An attempt was made to model the physicochemical transport of thorium in SLM and understand the mechanism of thorium transport.     

Hydrothermal conditions on Sn0.95Co0.05O2: nanostructures, ferromagnetism and optical behavior

We have studied the effect of hydrothermal conditions at constant temperature of 180 °C, varying preparation time for 15, 30 and 45 h on nanostructures of diluted magnetic semiconductor Sn_0.95Co_0.05O₂ (SC5). X-ray diffraction pattern confirm the tetragonal SnO₂ rutile phase. The transmission and scanning electron microscopy shows the resulting nanostructures i.e. nanospheres and nanorods. The proposed reaction mechanism is given. The Raman spectra show the formation of tetragonal rutile structure of SC5 nanostructures. Fourier transform infrared spectrum has been used to verify the existence of Sn–O bond. The photoluminescence spectra show that the emission spectral intensity increases gradually with decreasing grains size, increasing hydrothermal heating time of SC5 samples and exhibits an intense blue luminescence centered at a wavelength of 531 nm. The optical absorbance measurements revealed that the nanometric size of the materials influences the energy band gap. All the prepared SC5 samples exhibit room temperature ferromagnetism.