Structural and thermosensitive properties of novel octopus shape cyclotriphosphazenes

Three novel compounds (3–5) were synthesized from the reactions of non-geminal cis-2,4,6 diethylene glycol monobutyl ether substituted cyclotriphosphazene (2a) with ethylamine, hexylamine and dodecylamine. Compounds 3–5 were characterized by ³¹P NMR, MS and elemental analysis. The thermosensitive properties of compounds 3–5 were investigated. Compound 3 showed thermosensitive properties which might enable it to be used as a biomedical material.     

Structural and fluorescence properties of phenolphthalein bridged cyclotriphosphazatrienes

This study dealt with the reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆ (trimer) (1) with phenolphthalein (2) to give the phenolphthalein bridged compounds 3, 4 and 5. The phenolphthalein bridged cyclotriphosphazatriene derivatives are reported for the first time. The new compounds (3–5) are characterized by elemental analysis, mass spectrometry, UV–vis, FT-IR, ¹H, ³¹P NMR and fluorescence spectroscopy. The more bridged phenolphthalein groups show the higher intensity of the absorption bands in the UV–vis spectra. Fluorescence spectrum of compound 3 shows a small band in the lower spectral range, while the spectra of compounds 4 and 5 show more intense and a band in higher spectral range.     

Comparison of high-performance liquid chromatography of cyclotriphosphazene derivatives with one or two equivalent stereogenic centres

High-performance liquid chromatographic (HPLC) methods have been developed for investigating the stereogenic properties of two analogous series of dibenzylamino derivatives of cyclotriphosphazene containing either one or two equivalent stereogenic centres. Separation of the enantiomers of all the racemic compounds has been investigated by chiral HPLC using Whelk-01 and Chiralcel OD columns. In all cases, conditions for separation of enantiomers have been found using a Whelk-01 column with different ratios of tetrahydrofuran in n-hexane as the mobile phase. It is found that both the separation factor (alpha) and resolution factor (R(S)) of molecules with two equivalent stereogenic centres are greater than those for analogues with only one centre.     

Flow injection spectrofluorimetric determination of iron(III) in water using salicylic acid

A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed. Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used was 2 × 10⁻⁶ mol L⁻¹ salicylic acid in 0.1 mol L⁻¹ NH₄⁺/NH₃ buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L⁻¹ iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection was 0.3 μg L⁻¹ and the sampling rate was 60 h⁻¹. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully applied to the determination of low levels of iron in real samples (river, sea, and spring waters).     

First principles potential for the acetylene dimer and refinement by fitting to experiments

We report the definition and refinement of a new first principles potential for the acetylene dimer. The ab initio calculations were performed with the DFT-SAPT combination of symmetry-adapted intermolecular perturbation method and density functional theory, and fitted to a model site-site functional form. Comparison of the calculated microwave spectrum with experimental data revealed that the barriers to isomerization were too low. This potential was refined by fitting the model parameters in order to reproduce the observed transitions, an excellent agreement within ~1 MHz being achieved.     

Synthesis of pyrene end‐capped A6 dendrimer and star polymer with phosphazene core via “click chemistry”

Novel hexa‐armed and pyrene (Pyr) end‐capped phosphazene dendrimer [N₃P₃‐(Pyr)₆] and star polymer with poly(ε‐caprolactone) (PCL) arms [N₃P₃‐(PCL‐Pyr)₆] were prepared via two series of reactions. In these series, core‐first approach was used starting from a hexa‐hydroxy functional phosphazene derivative (N₃P₃‐(OH)₆). It was used as an initiator in the ring‐opening polymerization of ε‐caprolactone to prepare a hexa‐armed PCL star polymer (N₃P₃‐(PCL‐OH)₆). Hydroxyl functionalities of N₃P₃‐(OH)₆ and N₃P₃‐(PCL‐OH)₆ were then successfully converted into bromide and azide, in turn. Further end‐group modifications of azide functional dendrimer precursor (N₃P₃‐(N₃)₆) and star polymer (N₃P₃‐(PCL‐N₃)₆) were achieved quantitatively via the Cu(I) catalyzed click reaction between azide functional groups and 1‐ethynyl pyrene in the final step. Moreover, the pyrene end‐capped phosphazene dendrimer and star polymer were used in noncovalent functionalization of multiwalled carbon nanotubes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Evaluation of carbonic anhydrase and paraoxonase inhibition activities and molecular docking studies of highly water-soluble sulfonated phthalocyanines

The investigation of carbonic anhydrase and paraoxonase enzyme inhibition properties of water-soluble zinc and gallium phthalocyanine complexes ( 1 and 2 ) are reported for the first time. The binding of p-sulfonylphenoxy moieties to the phthalocyanine structure favors excellent solubilities in water, as well as providing an inhibition effect on carbonic anhydrase (CA) I and II isoenzymes and paraoxonase (PON1) enzyme. According to biological activity results, both complexes inhibited hCA I, hCA II, and PON1. Whereas 1 and 2 showed moderate hCA I and hCA II (off-target cytosolic isoforms) inhibitory activity (Ki values of 26.09 µM and 43.11 µM for hCA I and 30.95 µM and 33.19 µM for hCA II, respectively), they exhibited strong PON1 (associated with high-density lipoprotein [HDL]) inhibitory activity (Ki values of 0.37 µM and 0.27 µM, respectively). The inhibition kinetics were analyzed by Lineweaver–Burk double reciprocal plots. It revealed that 1 and 2 were noncompetitive inhibitors against PON1, hCA I, and hCA II. These complexes can be more advantageous than other synthetic CA and PON inhibitors due to their water solubility. Docking studies were carried out to examine the interactions between hCA I, hCA II, and PON1 inhibitors and metal complexes at a molecular level and to predict binding energies.     

Hydrolysis, Condensation, and Tetragonal Phase Formation in Sol-Gel Zirconia Prepared with Electron-Irradiated Alkoxide Solutions

Sol-gel zirconia precursor, zirconium n-butoxide in ter-butanol, was irradiated with 1.3 MeV electrons to a dose of 330 KGy. Gelling was instantaneously produced when an aqueous solution of sulfuric, hydrochloric or acetic acid was added to the irradiated solution; no hydrolysis catalyst was required. Samples were characterized with X-ray powder diffraction, infrared spectroscopy, and electron paramagnetic resonance. The electron irradiation accelerated hydrolysis and condensation, which avoided the stabilization of the tetragonal phase via carboxyls, and decreased the capability of sulfate ions to stabilize it. These results suggest that the stabilization of the tetragonal phase of sol-gel zirconia via carboxyl and sulfate ions depends on their diffusion in the sol.