The novel calix[4]arenes exhibiting prominent fluorescence were shown to be potential sensitive fluorimetric cation sensors. Comprehensive experimental and computational studies provided detailed insight into the corresponding complexation reactions.
A very small concentration of NaBr is added to ternary, transparent, and thermodynamically stable mixtures of water, ethanol, and octanol. Measuring the electrical conductivity along lines with constant water to ethanol ratios reveals remarkable composition dependencies similar to those found in classical surfactant-based microemulsions. Indeed, light-scattering experiments along the same composition lines and additional surface tension measurements confirm the onset of aggregation and possibly direct, bicontinuous, and reversed structures in these surfactant-free systems such as in classical microemulsions.
This work describes preparation and application of "homemade" chloride ISE enriched with iron oxides or zinc oxide nanoparticles. The prepared chloride ISE membrane was made of AgCl:Ag2S:PTFE = 1:1:2 and AgCl:Ag2S:PTFE = 2:1:2 enriched with mentioned nanoparticles in ratio 0.5-1.2 wt.%. Prepared membranes were used for chloride determination in perchloric acid (pH = 0-2) and acetic buffer (pH = 4-4.75). Due to the low method price, simplicity and a reasonably fast way of usage, it was considered as a possibility for chloride determination in high acid media. Two of prepared membranes (M1 and M4) have shown best characteristics. M1 showed linear response range for chloride between 2.0×10 −6 and 1×10 −1 mol L −1 , with a detection limit of 2.24×10 −6 mol L −1 and potential change of 44.39 mV per decade. M4 showed linear response range for chloride between 4.2×10-6 to 1×10-1 mol L −1 , limit of detection of 1.39×10-6 mol L −1 with potential change of 24.79 mV per decade at pH = 0.
The 6-oxonicotinate (6-Onic) salts of a one-dimensional cationic cobalt(II) or nickel(II) coordination polymers with 4,4′-bipyridine (4,4′-bpy), namely {[Co(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (1) and {[Ni(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (2), were prepared hydrothermally by reactions of cobalt(II) nitrate hexahydrate or nickel(II) nitrate hexahydrate, respectively, 6-hydroxynicotinic acid and 4,4′-bipyridine in a mixture of ethanol and water. In the hydrogen-bonded frameworks of 1 and 2, the one-dimensional polymeric chains of {[M(4,4′-bpy)(H2O)4]2+}n (M = Co, Ni), the 6-oxonicotinate anions and the lattice water molecules were assembled via strong intermolecular O–H···O and N–H···O hydrogen bonds and π–π interactions, leading to the formation of the representative hydrogen-bond ring motifs: trimeric R23(10) motif, the centrosymmetric tetrameric R24(8) and R24(12) motifs and the pentameric R45(12) motif. The isostructural coordination polymers 1 and 2 exhibited a different electrochemical behavior, as observed by cyclic voltammetry, which can be attributed to the nature of the metal ions (cobalt(II) vs. nickel(II)).
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