Sensing and fluorescence behaviors of complex formation between new lariat crown ethers bearing fluorescence sidearm and metal ions in methanol solution

Fluorescence spectroscopic properties of the complex formation between six new C-pivot16-crown-5 ethers bearing fluorescence side arms and metal ions are studied. Six new C-pivot 16-crown-5 ethers that carry fluorescence side arms were synthesized. The research also included the examination of different fluorescent behavior of the new lariat ethers in the presence of silver and sodium ions (Ag⁺ and Na⁺) in methanol. Because of the good fit of the cavity size of these 16-crown-5 ethers with the Ag⁺ and Na⁺ ions, remarkable change in fluorescent spectra were observed. The results showed that the new lariat crown ethers exhibited enhanced selectivity towards sodium ion, but silver ion show quenching abilities towards the ligands. Cooperative participations of the C-pivot side arm oxygen with the ring oxygen molecules in complexation was also confirmed by the single crystal X-ray crystallography of the complex, (C₂₇H₃₀O₇)·NaClO₄. The freezing of crown ring conformation and the diminishment of the chance of sidearm oscillation that occurred upon complexation with sodium ion are the main causes of fluorescent enhancement. The quenching caused by the addition of silver ion was found to explainable by the photo-induced electron transfer that results in the reduction of silver ions.     

The effect of methyl substitution on the spin-state in solid bis(methyl-substituted 2-pyridinalphenylimine)di(thiocyanato)iron(II)

Summary A series of iron(II) complexes of the type [FeL₂(NCS)₂] have been prepared and characterized, where L denotes the bidentate diimine ligands 2-pyridinalphenylimine orN-phenyl-2-pyridinaldimine (ppi) and its methyl-substituted derivatives. The electronic ground spin-state of iron(II) in these complexes has been studied by means of Mössbauer spectroscopy and magnetic susceptibility measurements.     

The First Triple‐Stranded Helical Metallosupramolecule with Metal Cluster Core

An unprecedented 3D framework, [Ag(Ag6(C2‐Me‐(Mepdz)₂)₃(CH₃CN))₂](ClO₄)₁₃, has been synthesized by using a ligand with both rigid pyridazine and flexible hydrazone segments, which represents to the best of our knowledge, the first example of metallosupramolecule built by the triple‐stranded helixes sharing the same penta‐silver core.     

tert-BuOK-mediated carbanion-yne intramolecular cyclization: synthesis of 2-substituted 3-benzylbenzofurans

A mild, efficient, and regioselective carbanion-yne intramolecular cyclization mediated by t-BuOK for the synthesis of 2-substituted 3-benzylbenzofurans is developed. It was started from o-iodophenol (1), based on O-alkylation, and the Sonogashira reaction in sequence to produce 2-(2-phenylethynylphenoxy)-1-arylalkanones (5). An intramolecular carbanion-yne 5-exo-dig cyclization reaction of 5, which was mediated by t-BuOK, yielded title benzofurans in good yields.     

Pressure- and heat-induced insertion of CO2 into an auxetic small-pore zeolite

When the small-pore zeolite natrolite is compressed at ca. 1.5 GPa and heated to ca. 110 °C in the presence of CO(2), the unit cell volume of natrolite expands by 6.8% and ca. 12 wt % of CO(2) is contained in the expanded elliptical channels. This CO(2) insertion into natrolite is found to be reversible upon pressure release.     

ToF-SIMS imaging of the nanoscale phase separation in polymeric light emitting diodes: effect of nanostructure on device efficiency

The nanostructure of the light emissive layer (EL) of polymer light emitting diodes (PLEDs) was investigated using force modulation microscopy (FMM) and scanning time-of-flight secondary ion mass spectrometry (ToF-SIMS) excited with focused Bi(3)(2+) primary beam. Three-dimensional nanostructures were reconstructed from high resolution ToF-SIMS images acquired with different C(60)(+) sputtering times. The observed nanostructure is related to the efficiency of the PLED. In poly(9-vinyl-carbazole) (PVK) based EL, a high processing temperature (60 °C) yielded less nanoscale phase separation than a low processing temperature (30 °C). This nanostructure can be further suppressed by replacing the host polymer with poly[oxy(3-(9H-9-carbazol-9-ilmethyl-2-methyltrimethylene)] (SL74) and poly[3-(carbazol-9-ylmethyl)-3-methyloxetane] (RS12), which have similar chemical structures and energy levels as PVK. The device efficiency increases when the phase separation inside the EL is suppressed. While the spontaneous formation of a bicontinuous nanostructure inside the active layer is known to provide a path for charge carrier transportation and to be the key to highly efficient polymeric solar cells, these nanostructures are less efficient for trapping the carrier inside the EL and thus lower the power conversion efficiency of the PLED devices.     

Densities,viscosities, refractive indices,and surface tensions for binary and ternary mixtures of 2-propanol,tetrahydropyran, and 2,2,4-trimethylpentane

Densities, viscosities, refractive indices, and surface tensions of the ternary system (2-propanol + tetrahydropyran + 2,2,4-trimethylpentane) at T = 303.15 K and its constituent binary systems (2-propanol + tetrahydropyran, 2-propanol + 2,2,4-trimethylpentane, and tetrahydropyran + 2,2,4-trimethylpentane) at T = (293.15, 303.15, 313.15, and 323.15) K were measured at atmospheric pressure. Densities were determined using a vibrating-tube densimeter. Viscosities were measured with an automatic microviscometer based on the rolling-ball principle. Refractive indexes were measured using a digital Abbe-type refractometer. Surface tensions were determined by the Wilhelmy-plate method. From these data, excess molar volumes, deviations in viscosity, deviations in refractive index, and deviations in surface tension were calculated. The results for the binary and ternary systems were fitted to the Redlich–Kister equation and the variable-degree polynomials in terms of compositions, respectively. The experimental and calculated quantities are used to study the nature of mixing behaviour between mixture components.     

Off-on-off luminescent switching of a dye containing imidazo[4,5-f][1,10]phenanthroline

A new acid-base fluorescent switch containing both imidazo[4,5-f][1,10]-phenanthroline and triphenylamine groups has been synthesized.Its fluorescence emissions and absorptions can be reversibiy changed through protonation/deprotonation of imidazole and amine moiety by controlling the intramolecular charge transfer(ICT) process,leading to off-on-off fluorescent molecular switching.     

Efficient copper-catalyzed S-vinylation of thiols with vinyl halides

The synthesis of vinyl sulfides through the coupling reaction of thiols with vinyl iodides, bromides, and chlorides is described. The thiols can couple with aryl iodides in the presence of only 0.5 mol % Cu(2)O without the need for an ancillary ligand. In the presence of 5 mol % of Cu(2)O and 10 mol % 1,10-phenanthroline as the ligand, the more challenging alkyl vinyl bromides can also be coupled with thiols, giving the vinyl sulfides in good to excellent yields.