Pei-Hua Zhao

Synthesis, crystal structures and electrocatalytic properties of bridgehead-C-functionalized diiron dithiolate complexes

To investigate the influence of bridgehead-C functionality in diiron dithiolate complexes on the molecular structure and electrocatalytic properties of [FeFe]-hydrogenase models, three new bridgehead-C-functionalized model complexes 1–3 have been synthesized and structurally characterized. Treatments of parent complex [(μ-SCH2)2CHCO2H][Fe2(CO)6] (A) with the esterification agents o-MeC6H4OH, p-ClC6H4OH, or p-HOC6H4CHO in the presence of 4-dimethylaminopyridine and dicyclohexylcarbodiimide in CH2Cl2 at room temperature resulted in formation of [(μ-SCH2)2CHCO2R][Fe2(CO)6] (R = o-MeC6H4–, 1; p-ClC6H4–, 2; p-OHCC6H4–, 3) in 53–55% yields. The new complexes 1–3 were characterized by elemental analysis, IR and NMR spectroscopy, and especially determined by X-ray crystallography. The electrochemical properties of 1–3 and the electrocatalytic H2 evolution catalyzed by 1 have been investigated by cyclic voltammetry, where 1 is a catalyst for HOAc proton reduction to H2 under electrochemical conditions.

Synthesis of a novel triazine flame retardant containing sulfur and its application to cotton fabrics

A novel triazine flame retardant (FR) has been successfully synthesized by the reaction of cyanuric chloride with sodium sulfanilate followed by diethanol amine. Its structure has been fully characterized by IR and 1H NMR spectroscopy. The effects of reaction solvent, acid-binding agent, reaction temperature, and molar ratio of starting materials on the yield of FR were investigated in detail. Experiments showed that when the molar ratio of intermediate I to diethanol amine is 1 to 1.2 in the presence of sodium carbonate as acid-binding agent in acetone-water at 45 °C, the yield of the obtained FR reaches 81.4%. Thermogravimetry (TG) test indicated that the FR has good thermostability and char-forming ability. In addition, the flame retardancy and thermal behavior of the cotton fabrics treated with FR were studied by limiting oxygen index (LOI), vertical flammability test, and thermogravimetry (TG) to evaluate the flameretardant performance of the target FR. These results demonstrated that the flame retardancy and thermal stability of the cotton fabrics treated with FR were clearly improved.

Highly flame retardancy of cotton fabrics with a novel phosphorus/nitrogen/silicon flame-retardant treating system

A novel reactive flame retardant (FR) containing phosphorus, nitrogen, and silicon was synthesized successfully, and its chemical structure was fully characterized by Fourier transform infrared spectrometry and nuclear magnetic resonance spectrometry (1H-NMR and 31P-NMR). Then it was used to impart flame resistance to cotton fabrics. Vertical flammability and limiting oxygen index test were used to evaluate the flame retardancy of the cotton fabrics treated with FR. When the cotton treated with 150 g/l FR and 50 g/l sodium hypophosphite, the finished cotton can pass the vertical flammability test. Thermogravimetry (TG) was used to evaluate thermal behavior of FR and cotton fabrics. TG results demonstrated that the FR has good thermostability and char-forming ability. After treatment with FR, the thermal stability of the cotton fabrics was clearly improved, indicating that the FR can protect cotton fabric from fire to a certain degree. Furthermore, attenuated total reflection Fourier transform infrared spectroscopy was utilized to characterize the chemical structure of FR treated cotton fabrics. Finally, the surface morphology in different regions of the treated cotton was observed using scanning electron microscopy.

Preparation and properties of flame retardant rigid polyurethane foam with phosphorus–nitrogen intumescent flame retardant

Ethanolamine spirocyclic pentaerythritol bisphosphonate (EMSPB), a novel intumescent flame retardant, was synthesized and used to improve the flame retardancy of rigid polyurethane foam (RPUF). The effects of EMSPB on the flammability, thermal stability, and mechanical properties of RPUF were discussed, respectively. Scanning electron microscopy (SEM) and compression strength tests showed that the EMSPB had favorable compatibility with the RPUF matrix and did not deteriorate the mechanical properties of the RPUF. Flammability of RPUF systems containing various contents of EMSPB was investigated by vertical burning test (UL-94) and limiting oxygen index (LOI) test. Results indicated that when the content of EMSPB was 25 wt%, the LOI of flame retardant RPUF could reach 27.5%, and a UL-94 V-0 rating was achieved. Thermogravimetric analysis showed that RPUF-containing EMSPB had a high yield of residual char at high temperatures, indicating that EMSPB was an effective charring agent. From the SEM observations of the residues of the flame retardant systems burned, the compact charred layers could be seen, which form protective shields to protect effectively the internal structure and inhibited the transmission of heat and heat diffusion during contacting fire.

Highly flame-retarding cotton fabrics with a novel phosphorus/nitrogen intumescent flame retardant

A novel phosphorus/nitrogen intumescent flame retardant, namely 6-chloro-4-(diethylamino phosphorate phosphoryl chloride)-2-(sodium 4-aminobenzensulfonate)-1,3,5-triazine (APPCABT), has been synthesized and characterized by elemental analysis, FT-IR, 1H-NMR and 31P{H}-NMR spectroscopies. To investigate the flame-retarding properties of the treated cotton fabrics, APPCABT was applied to the chemical treatment of the cotton fabrics surface. The flame-retarding performance of the treated samples with APPCABT was evaluated by limiting oxygen index (LOI). The thermal degradation behavior of the treated samples was studied using thermogravimetric analysis (TGA). The surface morphology of the treated samples was observed by scanning electron microscopy (SEM). These results show that APPCABT is both an intumescent flame retardant with high efficiency and an excellent char-forming agent for the flame-retarding treatment of cotton fabrics.

4-(Diphenyl­phosphan­yl)benzoic acid

In the title compound, C19H15O2P, the dihedral angles between the benzoic acid ring and the phenyl rings are 75.64 (7) and 80.88 (7)°; the dihedral angle between the phenyl rings is 81.35 (7)°. In the crystal, inversion dimers linked by pairs of O—H⋯O hydrogen bonds generate R 2 2(8) loops between the head-to-head carboxylic acid groups.

The effect of a pendant amine in phosphine ligand on the structure and electrochemical property of diiron dithiolate complexes

Abstract In order to explore the effect of a pendant amine on a phosphine ligand on the structure and electrochemical properties of diiron dithiolate complexes, this work reports the crystallographic and electrocatalytic comparisons of three diiron monophosphine complexes Fe2(μ-pdt)(CO)5{Ph2P(NHR)} [pdt = propanedithiolate (SCH2CH2CH2S); R = para-methoxycarbonylphenyl (C6H4CO2Me-p) (1), para-methoxyphenyl (C6H4OMe-p) (2) and phenyl (Ph) (3)] with a pendant amine and one reference analogue Fe2(μ-pdt)(CO)5{Ph2P(CH2Ph)} (4). While the new complex 4 has been characterized by elemental analysis and various spectroscopic techniques, the molecular structures of 3 and 4 were further determined by X-ray crystallography. In addition, the electrochemical properties of 1–4 were studied in acetonitrile (MeCN) in the absence and presence of acetic acid (HOAc) as a mild proton source using cyclic voltammetry (CV). This may demonstrate that they are found to be active electrocatalysts for proton reduction to hydrogen (H2).

Diphenyl-methyl isothio-cyanate.

The asymmetric unit of the title compound, C14H11NS, contains two molecules in which the dihedral angles between the phenyl rings are 77.23 (7) and 86.30 (7)°. No aromatic π–π stacking interactions are observed.

(E)-1-Phenyl-3-[4-(trifluoro­meth­yl)phen­yl]prop-2-en-1-one

In the title compound, C16H11F3O, the dihedral angle between the two rings is 48.8 (2)°. The crystal packing exhibits no classical intermolecular interactions between the molecules.

3-Nitro-2-phenyl-chroman.

In the title compound, C15H13NO3, the dihedral angle between the two aromatic rings is 79.25 (16)°.