Rong-a Hu

Enhanced dielectric and ferroelectric properties in PVDF composite flexible films through doping with diisopropylammonium bromide

A ferroelectric compound diisopropylammonium bromide (DIPAB) was dispersed into poly(vinylidene fluoride) (PVDF) matrix to form DIPAB/PVDF composite films. The composite film with different content of DIPAB was characterized by IR, XRD, DSC and SEM. The results indicated that soluble DIPAB could be homogeneously dispersed within PVDF matrix to form almost pure β-phase PVDF composite films without obvious agglomeration, and the crystallinity of PVDF polymer increased with increasing content of DIPAB inclusion. DIPAB/PVDF composite films exhibit very high dielectric constants and relatively low dielectric loss. Both dielectric constants and dielectric loss are frequency dependent and increased with increasing DIPAB content. DIPAB/PVDF composite films also exhibit enhanced ferroelectric properties. Incorporating DIPAB into PVDF is a useful way to improve the dielectric and ferroelectric property of PVDF composite films.

Discovery of a new type of organic ferroelectric materials in natural biomass dehydroabietylamine Schiff bases

Three kinds of Schiff bases, 5-chlorosalicylidene dehydroabietylamine (ClDHA), 5-bromosalicylidene dehydroabietylamine (BrDHA) and 5-nitrosalicylidene dehydroabietylamine (NODHA), have been prepared and characterized by elemental analyses, IR, circular dichroism (CD), and X-ray structural analyses. Ferroelectric, dielectric and NLO properties are reported for the first time in cheap natural biomass resource dehydroabietylamine derivatives and their ferroelectric properties can be easily tuned through the substituents of the aromatic aldehyde. With the increase in electron-withdrawing properties of the substituents from –Br to –Cl and then –NO2, the Ps values or the ferroelectric properties gradually increased.

Metal-induced property variation for a series of lanthanide-vanadium porphyrins

Three lanthanide-vanadium porphyrins, [LnV(TPPS)H2O]n (Ln = Tb(1), Dy(2), Er(3); H6TPPS = tetra(4-sulfonatophenyl)porphyrin), have been prepared from hydrothermal reactions and their structures were characterized by single crystal X-ray diffraction technique. The macrocyclic ring of H6TPPS is coplanar and the center is occupied by the vanadium(III) ion. The lanthanide(III) ions are bound by eight oxygen atoms to yield a distorted square anti-prism geometry. They are characteristic of a three-dimensional (3-D) open framework with a void space of around 210 A3. Fluorescence studies reveal that compounds 1–3 exhibit an emission band in the red region with the quantum yields being of 2.0%, 1.4% and 5.0%, respectively. CV/DPV results discover one quasi-reversible wave (1), one reductive peak (2) and two reductive peaks (3). Compounds 1–3 show largely different photophysical and electrochemical properties, although their structures only show tiny difference in lanthanide metal ions. This is due to metal-induced properties variation.

A series of thermal stable lanthanide porphyrins with a condensed three-dimensional porous open framework: Gas adsorption and magnetic properties

A series of lanthanide porphyrins, [LnIII(TPPSIV)]n·nH5O2 (Ln = La, Sm, Eu; H2TPPS = tetra(4-sulfonatophenyl)porphyrin), have been synthesized through solvothermal reactions and structurally characterized by single-crystal X-ray diffraction. These compounds are characterized by a condensed three-dimensional (3-D) porous open framework. Magnetic measurements reveal that these compounds show ferromagnetic, antiferromagnetic and paramagnetic behavior, respectively. All of the compounds exhibit highly thermal stability. The FT-IR and adsorption measurement of CO2 were also studied.

Chiral Schiff base ligated dioxomolybdenum (VI) complexes and their asymmetric catalytic properties in the epoxidation of styrene

Two series of Schiff base dioxomolybdenum (VI) complexes of the general formula [MoO2(L)(MeOH)] (L = D-glucosamine-derived Schiff base) have been synthesised, characterised and their asymmetric catalytic activities evaluated through the epoxidation of styrene. The molybdenum complexes with acetyl-protected D-glucosamine Schiff base ligands exhibited higher enanatioselectivity than those with unprotected sugar ligands. Protecting D-glucosamine by acetyl groups is an effective way to improve asymmetric catalytic epoxidation activities.