The halogen-free flame retardance of natural fiber is an everlasting challenge due to the well-known poor solubility of phosphazene in water. In this case, a new cyclotriphosphazene derivative (MCP) was synthesized. It was etherized hexamethylolmelamine (HMMM) and hexachloro-cyclotriphosphazene (HCCP) by one pot reaction. It was characterized by 1H NMR, 13C NMR, 31P NMR, FT-IR, TGA, SEM, limited oxygen index (LOI) and vertical flame testing. The MCP has good solubility in water and thermosetting MCP has compact structure which can expand several times after burning. Cotton gauze was soaked in six different concentration of aqueous solutions of MCP (0 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt % and 25 wt %, respectively) to obtain the flame retardant cloth. The cloth was soaked in 20 wt % MCP solution had higher char yield and LOI. They had no any afterflame and afterglow, and gauze 2- gauze 5 cannot be burned out in 12s ignition time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43555.
Several 3,3′-(1,4-phenylene)bis(1,5-diones) and their chalcone precursors have been prepared in good to excellent yield via aldol addition and Michael addition starting from 3-acetyl-2,5-dimethylfuran or 3-acetyl-2,5-dimethyl-thiophene with terephthalaldehyde in the presence of appropriate base NaOH or lithium diisopropylamide. The kind and amount of alkali played a critical role in improving the reaction rates and yields of the products. J. Heterocyclic Chem., (2011).
Novel 2-vinyl-8-hydroxyquinoline derivatives as potential antioxidants and regulators of H2O2-induced oxidative stress in rat bone marrow mesenchymal stem cells (MSCs) are first reported. The antiradical properties and the reducing power of these compounds were assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and auto-oxidation of pyrogallol method, respectively. The activity against lipid peroxidation was determined using ammonium thiocyanate method. The results revealed that introduction of electron-donating groups at 2nd position decreased the antioxidant activities of 8-hydroxyquinoline derivatives. In addition, compound 4, the structure of which is similar to melatonin, exhibited superior antioxidant activities in scavenging DPPH free radical, ˙O2 free radical, and anti-LPO activities. Except for compounds 7, 12, and 15, the other compounds exhibited a stimulatory effect on MSCs growth. Using hydrogen peroxide (H2O2), we also investigated the protective efficacy of 2-vinyl-8-hydroxyquinoline derivatives against oxidative stress-induced cell death of MSCs. Cell viability assayed by MTT method indicated that exposure of MSCs cultures to hydrogen peroxide resulted in a concentration-dependent decrease in cell viability, and compounds 4 and 5 at given concentration (2.62 × 10−3 m) could protect MSCs against H2O2-induced oxidative stress in bone mesenchymal stem cell (BMSCs).
Four kinds of 8-hydroxyquinoline conjugate bonded aromatic heterocyclic derivatives were designed and synthesized for potential use in the emission and electron conduction layers in organic light emitting devices, and as luminescent probes for metal ions. These novel compounds were characterized by IR, 1H NMR, 13C NMR, Mass and UV-visible spectra. The photoluminescent properties of the new compounds including the spectra (shape of bands, λex, λem), quantum yield (ϕf) and lifetime (τ) were investigated. Moreover, density functional theory method was used to study the relationship between the geometric configuration and emission wavelength. MTT assays of cell proliferation of rMSC and DPPH radical-scavenging tests suggested that the new compounds generate a significant increase of rMSC and demonstrate a good antioxidant activity.
N-Methyl-2-(4-N,N-diphenylaminophenyl)fulleropyrrolidine and N-methyl-2-(4-di-p-tolylaminophenyl)fulleropyrro- lidine were synthesized via the 1,3-dipolar cycloaddition reactions under microwave irradiation. The molecular structures were identified and characterized by MS, UV-Vis, FT-IR, 1H NMR and fluorescence spectra. Photoinduced intramolecular electron transfer process from C60 moiety to triphenylamine moiety have been studied by nanosecond laser flash photolysis. The optimized structure and the distribution of the frontier molecular orbitals for C60-TPA were obtained by using DFT method at B3LYP/6-31G(d) level. The results indicated that the intramolecular photoinduced electron transfer could occur in these compounds, which were in excellent agreement with the nanosecond transient absorption spectra observed experimentally in polar solvent. The electronic spectrum of the compound C60-TPA was studied by ZINDO method on the basis of the optimized geometrics, which was essentially consistent with experimental values.
A new 8-hydroxyquinoline derivative (5) was synthesized and characterized by ESI-MS, 1H NMR spectroscopy, elemental analysis and IR spectroscopy. The photophysical properties of compounds 5, 6 and 7 were also detemined by UV-vis and FL spectroscopy. The vibrational frequency of ligand 5 predicted by using B3LYP method is in good agreement with experimentally determined values. The compositions of the corresponding copper(II) and zinc(II) complexes were confirmed to be Cu(C29H21N2O)2·H2O (6) and Zn(C29H21N2O)2·H2O (7) by elementary analysis, thermogravimetry analysis and IR spectroscopy.
[60]Fullerenes attached with piperidinodithiocarboxylate dyad (1) and 7-chloro-1,2,3,4-tetrahydrophenazine (2) were efficiently synthesized through Diels-Alder cycloaddition with dienes. The physical properties of the triplet states of these compounds, in which strong electron acceptor moieties were covalently attached to C60 cores, were investigated by nanosecond laser flash photolysis. The excited triplet states in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region. The HOMO and LUMO were calculated by semiempirical methods AM1, which could predict the intramolecular photoinduced electron transfer in 1 and 2, and the nanosecond transient absorption spectra observed experimentally in solution were in excellent agreement with the calculated ones.
In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullerenes ( C60/C70 ) and organic donor [N, N, N′, N′-tetra (p-methylphenyl) −4, 4′-diamino-1, 1′-diphenyl sulphide (TPDAS) ], we studied characteristic absorption spectra in the near-IR region obtained from 532 nm nanosecond laser flash photolysis of a mixture of the fullerenes (C60/C70) and TPDAS in polar solvents. When fullerenes (C60/C70) were photoexcited, the rise of the radical anion of fullerenes (C60/C70) with the rapid decay of their excited triplet states were observed in benzonitrite. It can be deduced that the electron transfer reaction does take place from TPDAS to excited triplet state of fullerenes (C60/C70). The rate constants (ket) and quantum yields (ϕet) of this process have been also evaluated.
Photoinduced electron transfer (PET) processes between C60-C6H8SO and Tetrathiafulvalene (TTF) have been studied by nanosecond laser photolysis. Quantum yields (ϕet) and rate constants of electron transfer (ket) from TTF to excited triplet state of [60] fullerene-containing cyclic sulphoxide in benzonitrile (BN) have been evaluated by observing the transient absorption bands in the NIR region. With the decay of excited triplet state of [60] fullerene-containing cyclic sulphoxide, the rise of radical anion of [60] fullerene-containing cyclic sulphoxide is observed.
The photoinduced electron-transfer reaction of N, N, N', N'-tetra-(p-methylphenyl)-4,4'-diamino-1,1'-diphenyl ether (TPDAE) and fullerenes (C60/C70) by nanosecond laser flash photolysis occurred in benzonitrile. Transient absorption spectral measurements were carried out during 532 nm laser flash photolysis of a mixture of the fullerenes (C60/C70) and TPDAE. The electron transfer from the TPDAE to excited triplet state of the fullerenes (C60/C70) quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C60/C70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes (C60/C70) and radical cations of TPDAE are expected to appear.
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