Synthesis and Characterization of High Performance Poly(amide-imide)s based on a New Diimide-diacide and Various Diamines

A new diimide-diacid, (4-(4-(2,6-diphenylpyridin-4yl)phenoxy)phenyl)-1,3-bis(trimellitimidobenzene) (PPMIB), was synthesized from the condensation reaction of a new diamine, (4-(4-(2,6-diphenylpyridin-4yl)phenoxy)phenyl)-3,5-diaminobezamide (PPDA), and trimellitic anhydride carboxylic acid (TMAA) in glacial acetic acid. The diimide-diacid (PPMIB) was characterized by FT-IR, ¹H-NMR and elemental analysis. A series of novel aromatic poly(amide-imide)s (PAIs) was synthesized by using direct polycondensation of PPMIB with various diamines in NMP in the presence of triphenylposphite and pyridine as condensing agents. The resulting PAIs were amorphous, readily soluble in many polar aprotic solvents and showed inherent viscosities of 0.35–0.50 dL/g. According to thermal analysis, these polymers exhibited glass transition temperatures (T_gs) in the range of 202–280°C and temperature of 10% weight loss (T₁₀) varied from 400 to 545°C in N₂. These polymers in NMP solution exhibited strong UV-Vis absorption maxima at 320°C nm and their fluorescence emission peaks appeared around 410–565 nm.     

Synthesis and Characterization of β‐Co(OH)2, CuO and ZnO Nanostructures by Solvothermal Method without Any Additive

β‐Co(OH)₂, CuO and ZnO nanostructures with plate‐like, particle‐like and flower‐like morphologies were prepared through the use of simple solvothermal method using of melt salt and 1,10‐phenanthroline as complexing agent and sodium hydroxide. β‐Co(OH)₂ consisted of a plate‐like structure, and the nanoplates size was about 29 nm. The structure was comprised of regular sheets which were assembled together. Furthermore, the as‐obtained β‐Co(OH)₂ nanoplates can be easily converted into Co₃O₄ nanoplates by calcining in air at 500 °C for 2 h. The results indicate that ZnO powder is of hexagonal wurtzite structure and well crystallized with high purity. CuO powder is pure monoclinic‐structured crystalline. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT‐IR) spectra. Possible formation mechanism of the nanostructures is proposed.     

Microwave-Promoted Facile and Rapid Synthesis Procedure for the Efficient Synthesis of 5,5-Disubstituted Hydantoins

A fast, general, environmentally friendly, and facile method for preparation of 5, 5-disubstituted hydantoins from the reaction between ketone (or aldehyde) derivatives with KCN and ammonium carbonate under microwave irradiation is presented. The microwaves remarkably accelerated this reaction, the reaction times decreased dramatically, the reaction conditions were milder, and the yields were also greater. Also a comparative study of microwave versus classical conditions has been done. All the products were characterized by infrared, NMR, and CHN analysis, and their melting points are identical to those of the known compounds reported in the literature. This method might be useful in the future for the preparation of similar derivatives.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]     

Modified Merrifield resin-supported PCP pincer palladium nanoparticles as a new polymeric catalyst for cyanation of aryl iodides

A new tridentate PCP pincer palladium (Pd) complex based on cross-linked Merrifield resin containing phosphinite ligand was synthesized and characterized. This polymeric catalyst was used in preparation of benzonitriles from different aryl iodides using potassium hexacyanoferrate (II) as a cyanide source. The presence of active metallic Pd in the catalyst was verified by X-ray power diffraction and X-ray photoelectron spectroscopy techniques. Transmission electron microscopy showed good dispersion of catalytic sites in the range of 30–50 nm. The catalyst is easily separated from reaction mixture and can be used for several times in repeating cycles without considerable loss of activity. The leaching of Pd from the support is negligible, which was confirmed by inductively coupled plasma–optical emission spectrometry and hot filtration test.     

Synthese und Kristallstrukturen der Phosphaniminato-Komplexe [SbF2(NPEt3)]2 und [SbF(NPEt3)2]2 sowie von NMe4+SbF4−

Synthesis and Crystal Structures of the Phosphoraneiminato Complexes [SbF₂(NPEt₃)]₂ and [SbF(NPEt₃)₂]₂ as well as of NMe₄⁺SbF₄^? The title compounds have been prepared from antimony trifluoride with the silylated phosphaneimine Me₃SiNPEt₃ and [NMe₄]F, respectively. They were characterized by IR spectroscopy and by crystal structure determinations. [SbF₂(NPEt₃)]₂ : Space group Pbca, Z = 8, structure determination with 1264 unique reflections, R₁ = 0.028 for reflections with I > 2σ(I). Lattice dimensions at ?80°C: a = 1284.8, b = 1162.4, c = 1380.4 pm. The compound forms centrosymmetric dimeric molecules, in which the Ψ-trigonal-bipyramidal coordinated antimony atoms are linked via μ₂-N bridges of the NPEt₃^? ligands. [SbF(NPEt₃)₂]₂ : Space group P2₁/c, Z = 4, structure determination with 2270 unique reflections, R₁ = 0.029 for reflections with I > 2μ(I). Lattice dimensions at ?75°C: a = 815.8, b = 1121.2, c = 2068.5 pm, β = 101.09°. The compound forms centrosymmetric dimeric molecules, in which the Ψ-trigonal-bipyramidal coordinated antimony atoms are linked via μ₂-N bridges of one of the two NPEt₃^? ligands. The other NPEt₃^? group is terminally connected. NMe₄⁺SbF₄^? : Space group P2₁/c, Z = 4, structure determination with 1503 unique reflections, R₁ = 0.069 for reflections with I > 2μ(I). Lattice dimensions at ?50°C: a = 539.80, b = 896.10, c = 1760.3 pm, β = 90.338°. The compound includes monomeric SbF₄^? ions with distorted Ψ-trigonal-bipyramidal environment of the antimony atoms.     

Synthese und Kristallstruktur des Kalium‐Iminophosphanids [K4(THF)3(Me3SiNPEt2)2(OSiMe2OSiMe2O)]2

The potassium iminophosphanide complex [K₄(thf)₃(Me₃SiNPEt₂)₂(OSiMe₂OSiMe₂O)]₂ has been obtained by a melt reaction of Me₃SiNPEt₃ with potassium hydride at 140 °C in the presence of silicon grease (—OSiMe₂—)_n and subsequent crystallization from thf solution. The colourless moisture sensitive single crystals are characterized by X‐ray diffraction: Space group P1¯, Z = 1, lattice dimensions at —70 °C: a = 1135.9(3), b = 1250.0(3), c = 1866.1(4) pm, α = 92.65(1)°, β = 100.80(1)°, γ = 93.57(1)°, R₁ = 0.0604. The centrosymmetric dimeric cluster aggregate is formed by two of the eight potassium ions which are connected with the central oxygen atom of both the (OSiMe₂OSiMe₂O)^2— chains as well as with one of their terminal O atoms each. The remaining potassium ions are connected with the phosphorus atoms of the iminophosphanide groups (Me₃SiNPEt₂)^— as well as with its nitrogen atoms. They are terminally solvated by thf molecules.     

A new model to study the phase transition from microstructures to nanostructures in ionic/ionic surfactants mixture

The phase behavior and aggregate structures of mixtures of the oppositely charged surfactants cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) are explored at high dilution by pulsed field gradient stimulated echo (PFG-STE) NMR. The aggregation numbers and hydrodynamic radii of vesicles and mixed micelles were determined by a combination of viscosity and self-diffusion coefficient measurements. The average size of the mixed micelles was larger than that of micelles containing uniformly charged head groups. Analysis of the variations of the self-diffusion coefficient and viscosity with changing concentration of CTAB or SDS in the cationic-rich and anionic-rich regions revealed a phase transition from vesicles to mixed micelles. Differences in the lengths of the CTAB and SDS hydrophobic chains stabilize vesicles relative to other microstructures (e.g., liquid crystalline and precipitate phase), and vesicles form spontaneously over a wide range of compositions in both cationic-rich and anionic-rich solutions. The results obtained from conductometry measurements confirmed this transition. Finally, according to the capacitor model, a new model was developed for estimating the surface potentials and electrostatic free energy (g(elec)). Then we investigated the variations of electrostatic and transfer free energy in phase transition between mixed micelle and vesicle.     

Development of a stability-indicating CE assay for the determination of amlodipine enantiomers in commercial tablets

A simple, accurate, precise and sensitive method using CD for separation and stability indicating assay of enantiomers of amlodipine in the commercial tablets has been established. Several types of CD were evaluated and best results were obtained using a fused-silica capillary with phosphate running buffer (100 mM, pH 3.0) containing 5 mM hydroxypropyl-alpha-CD. The method has shown adequate separation for amlodipine enantiomers from its degradation products. The drug was subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The range of quantitation for both enantiomers was 5-150 microg/mL. Intra- and inter-day RSD (n=6) was <4%. The limit of quantification that produced the requisite precision and accuracy was found to be 5 microg/mL for both enantiomers. The LOD for both enantiomers was found to be 0.5 microg/mL. Degradation products produced as a result of stress studies did not interfere with the detection of enantiomers and the assay can thus be considered stability indicating.