Xiangkai Fu

Synthesis and characterization of novel electrochromic and photoresponsive materials based on azobenzene-4,4′-dicarboxylic acid dialkyl ester

Novel electrochromic and photoresponsive materials based on azobenzene-4,4′-dicarboxylic acid dialkyl ester derivatives (ADDEDs) were successfully prepared and characterized through nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and high-performance liquid chromatography-mass spectrometry. The electrochromic behavior, electrochromic mechanism, electro-optical properties, and photoresponsive properties of ADDEDs were investigated through cyclic voltammetry and ultraviolet-visible absorption spectra. ADDEDs displayed not only outstanding electrochromic behavior but also good and reversible photoisomerization properties even under electrochromic conditions. Electrochromic devices (ECDs) based on ADDEDs were fabricated, and their electrochromic performance was analyzed. The ECDs presented a color change from colorless to magenta between 0.0 V (bleached state) and ±3.0 V (colored state). In addition, the ECDs exhibited fast switching times, reasonable contrast, satisfactory optical memories, and redox stability. The novel redox-active azobenzene derivatives are promising candidates for full-color EC display devices, electronic paper, smart windows, optical memory devices, dual-stimuli-responsive systems, as well as other potential new applications.

A series of novel types of immobilized chiral salen Mn(III) on different organic polymer-inorganic hybrid crystalline zinc phosphonate-phosphate act as catalysts for asymmetric epoxidation of unfunctionalized olefins

A novel type of layered crystalline organic polymer-inorganic hybrid material, zinc poly(styrene-phenylvinylphosphonate)-phosphate (ZnPS-PVPA) was synthesized and an array of new heterogeneous catalysts were gained by grafting chiral salen Mn(III) onto the ZnPS-PVPA, and characterized by FT-IR, diffusion reflection UV-vis, AAS, N2 volumetric adsorption, SEM, TEM, XPS, XRD and TG. The immobilized chiral salen Mn(III) catalysts exhibited higher chiral induction in the asymmetric epoxidation of α-methylstyrene and indene with m-CPBA and NaIO4 as oxidants than the corresponding homogeneous catalyst did (ee, >99% vs. 54% and >99% vs. 65%). And the heterogeneous catalysts are relatively stable and can be recycled nine times in the asymmetric epoxidation of α-methylstyrene. Furthermore, this novel type of catalyst can also be efficiently used in large-scale reactions with superior catalytic ability being maintained at the same level, which possessed the potentiality for application in industry.

Efficient synthesis of zirconium poly(styrene-phenylvinylphosphonate)phosphate-supported proline as a recyclable catalyst for direct asymmetric aldol reactions in water

A completely non-chromatographic and highly large-scale adaptable synthesis of zirconium poly(styrene-phenylvinylphosphonate)phosphate-supported L-proline (ZrPS-PVPA-Pr) has been developed in only three steps overall. Catalyst 1c was determined to be efficient for the asymmetric direct aldol reaction (only 0.5 mol% of 1c was used) in the presence of water at room temperature, with an enantiomeric excess as high as 99%. In addition, water was identified as one of the most significant reaction condition parameters due to the characteristics of the organic–inorganic hybrid catalyst support. Catalyst 1c was easily recovered by simple filtration and could be reused at least six times with little loss of activity and enantioselectivity. Catalyst 1c can be used efficiently on a large-scale while maintaining the enantioselectivities of the aldol reactions. Therefore, this method has the potential for application in industry.

Chiral salen Mn(III) complexes immobilized onto crystalline aluminium oligo-styrenyl phosphonate-hydrogen phosphate (AlSPP) for heterogeneous asymmetric epoxidation

A novel type of organic polymer–inorganic hybrid material layered crystalline aluminium oligo-styrenyl phosphonate-hydrogen phosphate (AlSPP) was designed and prepared in the absence of any template. The chiral salen Mn(III) complex immobilized onto alkoxy-modified AlSPP was synthesized and characterized by FT-IR, diffusion reflection UV-vis, AAS, N2 volumetric adsorption, SEM, TEM, XRD, TG and AFM. The supported catalysts displayed superior catalytic activities in the asymmetric epoxidation of α-methylstyrene and indene with m-CPBA as an oxidant. Delightfully, the heterogeneous catalysts afforded a remarkable increase in conversion and ee values without the expensive O-coordinating axial bases for the asymmetric epoxidation of olefins. The catalysts can be easily recovered and reused with a slight decrease in activity and enantioselectivity after ten cycles. Furthermore, they could also be efficiently used in large-scale reactions with the enantioselectivity being maintained at the same level, which provided the potentiality for application in industry.

Intercalation of non-aromatic heterocyclic amines into layered zirconium glycine-N,N-dimethylphosphonate

New materials were prepared by intercalation reactions between layered zirconium glycine-N,N-dimethylphosphonate (ZGDMP) and non-aromatic heterocyclic amines: piperazine, piperidine, and morpholine. X-ray powder diffraction patterns showed that the entrance of piperazine, piperidine, and morpholine caused an interlayer expansion of 0.40 nm, 0.66 nm, and 0.67 nm, respectively. The infrared spectra were in agreement with an acid-base reaction, involving layered acid host COOH of ZGDMP and basic center atoms of guest molecules. Thermogravimetric curves revealed thermal stability of the intercalation compounds and content of the inserted amine molecules. These results indicate that non-aromatic heterocyclic amines were intercalated into the galleries of host ZGDMP.

Intercalation of basic amino acids into layered zirconium proline-N-methylphosphonate phosphate

Intercalation of basic amino acids into layered zirconium proline-N-methylphosphonate phosphate (α-ZPMP) was investigated at room temperature. Three kinds of host-guest compounds were prepared and characterised by elemental analysis, inductively coupled plasma analysis (ICP), Fourier transform infrared spectrum (FT-IR), Raman spectrum, X-ray powder diffraction (XRD) and thermoanalysis. The interaction of amino acid guests with P-OH of α-ZPMP host was documented by FT-IR and Raman spectra. In addition, the XRD patterns indicated that l-arginine or l-lysine were intercalated into the interlayer galleries of α-ZPMP host; the interlayer distances of the Larginine and l-lysine intercalation compounds were expanded from 1.520 nm to 2.218 nm and 2.207 nm, respectively. l-arginine and l-lysine would be arranged as a mono-molecule layer in different orientations. The interlayer distance of l-histidine (d = 1.522 nm) was similar to that of α-ZPMP host (d = 1.520 nm), l-histidine might be adsorbed on the outer surface of the α-ZPMP host. Thermoanalysis showed that the intercalated l-arginine and l-lysine were removed at 110–305°C or 150–250°C, respectively, the adsorbed l-histidine was released at a temperature of up to 320°C.

Simple proline derivatives as recoverable catalysts for the large-scale stoichiometric aldol reactions

Simple, inexpensive, highly active, recoverable and reusable proline-based organocatalysts have been developed to promote direct stoichiometric aldol reactions with excellent enantioselectivities. The proline-based organocatalyst 1c is highly efficient for the stoichiometric aldol reactions of a wide range of aromatic aldehydes with cyclic ketones, and the resulting aldol products could be obtained with up to 99 ∶ 1 anti/syn ratio and >99% ee. The proline-based organocatalyst 1c can be easily recovered and reused, and only a slight decrease in enantioselectivities was observed after seven cycles. The proline-based organocatalyst 1c can be efficiently applied to large-scale reactions with the enantioselectivities being maintained at the same level, which demonstrates potential application in industry.

Enantioselective epoxidation of nonfunctionalized alkenes catalyzed by recyclable new homochiral bis-diamine-bridged bi-Mn(salen) complexes

Three new homochiral bis-diamine-bridged bi-Mn(salen) complexes were synthesized. Their catalysis on asymmetric epoxidation of α-methylstyrene, styrene and indene was studied with NaClO and m-CPBA as oxidants respectively. This homogeneous catalyst exhibited comparable catalytic activity and enantioselectivity to the Jacobsen’s catalyst in the asymmetric epoxidation of unfunctionalized olefins. Furthermore, the catalyst could be conveniently recovered and reused at least five times without significant losses of both activity and enantioselectivity. Specially, it also could be efficiently used in large-scale reactions with superior catalytic disposition being maintained at the same level, which provided the potential for the applications in industry. The effect of axial bases, temperature and solvent on activity and enantioselectivity of the catalytic system were also studied.

Highly efficient direct large-scale stoichiometric aldol reactions catalyzed by a new diamine salt in the presence of water

A new type of primary–tertiary diamine salt prepared can be used as a catalyst for direct aldol reaction and can display high yields, diastereoselectivities (up to 99 : 1), and enantiomeric excesses (up to 98%), by using stoichiometric amounts of cyclic ketones and various aryl aldehydes in the presence of water. This new catalyst can also be efficiently applied in large-scale reactions with the enantioselectivity being maintained at the same level, which indicates the potential for applications in industry.

Synthesis of the New Type of Water-Soluble Ligand N,N-Bis-(diphenylphosphinomethyl)-2-aminoethylphosphonic Acid (Ph2PCH2)2NCH2CH2PO3H2 and Its Sodium Salt

The novel water-soluble ligand, N,N-bis(diphenylphosphinomethyl)-2-amino-ethylphosphonic acid, (Ph2PCH2)2NCH2CH2PO3H2, had been synthesized in quantitative yield by reaction of 2-aminoethylphosphonic acid with bis(hydroxymethyl)- diphenylphosphonium chloride in water. Its mono- and disodium salts, which can be used as water-soluble ligands for transition metal complex catalysts, were also easily prepared under mild conditions.