Synthesis of novel disulfide-bridged dilactam crown ethers

The novel macrocyclic dilactams with redox-switched disulfide linkage were synthesized.These compounds were obtained from 2,2'-dithiodibenzoyl chloride in the macrocyclization step by fast addition method in moderate yields.     

Detours for Reaching at New Germylenes, Silylenes, Carbenes, and Carbenogermylenes through Substituted Cyclopropenylidenes at Ab initio and DFT Levels

Heavier atom containing X ₂SiC₂, and X ₂GeC₂ cyclopropenylidenes transform into new silylenes, germylenes, and carbenogermylenes at DFT and ab initio levels (X = H, CN, NH₂, and OMe). The number of transformations or rearrangements appear roughly proportional to the covalent radii of the group 14 elements (Ge > Si > C).     

Simultaneous dual-wavelength lasing of an erbium-doped fibre laser over wide spectrum range by intracavity loss optimisation

This letter reports a new technique to achieve a wide range of simultaneous dual output lasing of an erbium-doped fibre laser. The range covers a wide spectrum of 30 nm. This range is achieved by optimising the intracavity loss of the fibre loop in the laser. The wavelength is tuned via a tuneable bandpass filter. These dual lasing outputs are kept within a 0.5 dB power difference.     

Concentration dependent tautomerism in green [Cu(HL¹)(L²)] and brown [Cu(L¹)(HL²)] with H₂L¹ = (E)-N'-(2-hydroxy-3-methoxybenzylidene)benzoylhydrazone and HL² = pyridine-4-carboxylic (isonicotinic) acid

The in situ formed hydrazone Schiff base ligand (E)-N'-(2-hydroxy-3-methoxybenzylidene)benzoylhydrazone (H?L1) reacts with copper(II) acetate in ethanol in the presence of pyridine-4-carboxylic acid (isonicotinic acid, HL2) to green-[Cu(HL1)(L2)]·H?O·C?H?OH (1) and brown-[Cu(L1)(HL2)] (2) complexes which crystallize as concomitant tautomers where either the mono-anion (HL1)? or di-anion (L1)2? of the Schiff base and simultaneously the pyridine-carboxylate (L2)? or the acid (HL2) (both through the pyridine nitrogen atom) function as ligands. The square-planar molecular copper(II) complexes differ in only a localized proton position either on the amide nitrogen of the hydrazone Schiff base in 1 or on the carboxyl group of the isonicotin ligand in 2. The proportion of the tautomeric forms in the crystalline solid-state can be controlled over a wide range from 1:2 = 95?:?5 to ～2?:?98 by increasing the solution concentration. UV/Vis spectral studies show both tautomers to be kinetically stable (inert), that is, with no apparent tautomerization, in acetonitrile solution. The UB3LYP/6-31+G* level optimized structures of the two complexes are in close agreement with experimental findings. The solid-state structures feature 1D hydrogen-bonded chain from charge-assisted O((-))H-N and O-H((-))N hydrogen bonding in 1 and 2, respectively. In 1 pyridine-4-carboxylate also assumes a metal-bridging action by coordinating a weakly bound carboxylate group as a fifth ligand to a Cu axial site. Neighboring chains in 1 and 2 are connected by strong π-stacking interactions involving also the five- and six-membered, presumably metalloaromatic Cu-chelate rings.     

Polypyrrole/hexagonally ordered silica nanocomposite as a novel fiber coating for solid-phase microextraction

A highly porous fiber coated polypyrrole/hexagonally ordered silica (PPy/SBA15) materials were prepared for solid-phase microextraction (SPME). The PPy/SBA15 nanocomposite was synthesized by an in situ polymerization technique. The resulting material was characterized by the scanning electron microscopy, thermogravimetric analysis and differential thermal analysis. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, desorption time and desorption temperature. In optimum conditions (extraction temperature 70°C, extraction time 20 min, ionic strength 20% (WV(-1)), stirring rate 500 rpm, desorption temperature 270°C, desorption time 5 min) the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 5.0% and 9.3% for the tested compounds. The quantitation limit for the studied compounds were between 13.3 and 66.6 pg mL(-1). The life span and stability of the PPy/SBA15 fiber are good, and it can be used more than 50 times at 260°C without any significant change in sorption properties. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.     

Practicality of the cyclotron production of radiolanthanide 142Pr: a potential for therapeutic applications and biodistribution studies

Radiolanthanide praseodymium-142 (T _1/2 = 19.12 h, E _?? ^?  = 2.162 MeV (96.3%), E?? = 1575 keV (3.7%)) due to its high ??-emission and low specific ??-emission could not only be a therapeutic radionuclide, but also a suitable radionuclide in order for biodistribution studies. Conventionally, ¹⁴²Pr produces via ¹⁴¹Pr(n,??)¹⁴²Pr reaction by irradiation in a low-fluence reactor and this study evaluates cyclotron reaction production of it. ¹⁴²Pr excitation function via ^natLa(??,n)¹⁴²Pr, ¹⁴²Ce(p,n)¹⁴²Pr, and ^natPr(d,p)¹⁴²Pr reactions were calculated by TALYS-1.2 and EMPIRE-2.19beta codes, and with the data taken from the TENDL-2010 database. In addition, we compared them with the reported measurement by experimental data. Requisite thickness of targets was obtained by SRIM-2010 code for each reaction. The ¹⁴²Pr production yield was evaluated with attention to excitation function and stopping power. Similar to reactor produced ¹⁴²Pr; ¹⁴¹Pr impurity exists in cyclotron produced ¹⁴²Pr while it could not be separated by chemical methods. Therefore, cyclotron and reactor produced ¹⁴²Pr will be in carrier added form.     

Cyclotron production of <Superscript>169</Superscript>Yb: a potential radiolanthanide for brachytherapy

In the present study, ytterbium-169 was produced via the ¹⁶⁹Tm(p, n)¹⁶⁹Yb nuclear process at the AMIRS (Cyclone-30, IBA, Belgium) cyclotron, irradiating Tm₂O₃ with proton particles of 15 MeV primary energy and 20 μA current for 20 min. Deposition of Tm₂O₃ on Cu substrate was carried out via by the sedimentation method. The 543 mg of thulium(III)oxide with 108 mg of ethyl cellulose and 8 mL of acetone were used to prepare a Tm₂O₃ layer of 11.69 cm². Yields of about 0.643 MBq ¹⁶⁹Yb per μAh were experimentally obtained. ¹⁶⁹Yb was separated in 80 ± 5% radiochemical yield using liquid–liquid extraction. Solvent extraction of no-carrier-added ¹⁶⁹Yb from irradiated thulium(III)oxide target hydrochloric solution was investigated using di-(2-ethylhexyl)phosphoric acid (HDEHP).     

Production of <Superscript>122</Superscript>Sb for the study of environmental pollution

This article presents, ¹²²Sb (T _1/2 = 2.723 days, I _β- = 97.59%) was produced via the ^natSn(p,xn) nuclear process at the AMIRS (Cyclone-30, IBA, Belgium). The electrodeposition experiments were carried out by potassium stannate trihydrate (K₂Sn(OH)₆) and potassium hydroxide. The optimum conditions of the electrodeposition of tin were as follows: 40 g/L ^natSn, 20 g/L KOH, 115 g/L K₂Sn(OH)₆, DC current density of 5 A/dm² with a bath temperature of 75 °C. The electroplated Tin-target was irradiated with 26.5 MeV protons at current of 180 μA for 20 min. Solvent extraction of no-carrier-added ¹²²Sb from irradiated Tin-natural target hydrochloric solution was investigated using di-n-butyl ether (C₈H₁₈O). Yields of about 3.61 MBq/μAh were experimentally obtained.