Synthesis and properties of new ionic liquid crystals based on para-nitroazobenzene with substitution vinylimidazolium ion group

A new series of ionic liquid crystals (ILCs), 1-(4-(4-nitrophenylazo)phenyloxy) vinyl-3-methyl-1H-imidazol-3-ium bromide salts (C _n , n?=?6, 10) were synthesised. Their chemical structures were determined by ¹H NMR, ¹³C NMR, UV spectroscopy and elemental analysis. The liquid crystalline properties were investigated by differential scanning calorimetry, polarising optical microscopy, and powder X-ray diffraction. These measurements showed that C _n (n?=?6, 10) exhibit smectic liquid crystalline phases with focal-conic fan-shaped textures. The introduction of vinylimidazolium group onto the azobenzene enhances the thermal stability of the smectic state, which play an important role in forming the smectic layer structure.     

A universal method to calculate the surface energy density of spherical surfaces in crystals

Surface energy plays an important role in the mechanical performance of nanomaterials;however, deter-mining the surface energy density of curved surfaces remains a challenge. In this paper, we conduct atomic simulations to calculate the surface energy density of spherical surfaces in various crystalline metals. It is found that the average sur-face energy density of spherical surfaces remains almost constant once its radius exceeds 5 nm. Then, using a geomet-rical analysis and the scaling law, we develop an analytical approach to estimate the surface energy density of spherical surfaces through that of planar surfaces. The theoretical pre-diction agrees well with the direct atomic simulations, and thus provides a simple and general method to calculate the surface energy density in crystals.     

Synthesis and Characterization of La‐Doped Fe3O4‐Polyaniline Magnetic Response Nanocomposites

Lanathum (La)‐doped Fe₃O₄ magnetic nanoparticles were prepared in aqueous solution at room temperature, then La‐doped Fe₃O₄‐polyaniline (PANI) nanocomposites containing a dispersion of La‐doped Fe₃O₄ nanoparticles were synthesized via in‐situ polymerization of aniline monomer. The structure and properties of the synthesized samples were characterized with X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometry (ICPAES), and a vibrating sample magnetometer (VSM). The resulting particles of La‐doped Fe₃O₄ and La‐doped Fe₃O₄‐PANI were almost spherical with diameters ranging from 15 to 25 nm and 25 to 85 nm, respectively. The La‐doped Fe₃O₄‐PANI composite presented core‐shell structures; polyaniline covered the La‐doped Fe₃O₄ completely. The specific saturation magnetization of La‐doped Fe₃O₄‐PANI depended on the starting material of La‐doped Fe₃O_4. It increased with increasing amounts of La and Fe₃O₄ content.     

N-甲基吡咯烷酮与H_nXW_(12)O_(40)·mH_2O(X=P,Si,Ge)电荷转移盐的合成、表征及非线性光学性质研究

由N -甲基吡咯烷酮和HnXW1 2 O40 ·mH2 O(X =P ,Si,Ge)合成了具有非线性光学性质的电荷转移盐 ,(NMPH) 3PW1 2 O40 ·CH3CN(I) ,(NMPH) 4 SiW1 2 O40 ·CH3CN(Ⅱ )和 (NMPH) 4 GeW1 2 O40 ·CH3CN(Ⅲ ) .并由元素分析 ,红外光谱 ,漫反射电子光谱进行了表征。结果表明杂多酸形成电荷转移盐后其阴离子结构未变 ;N -甲基吡咯烷酮通过N原子与酸中的质子H+结合成阳离子而成盐 ,光激发下阴阳离子之间可以发生电荷转移 ,非线性光学性性质研究表明 ,电荷转移盐的倍频效应强度分别为I2ωⅠ =0 .6IKDP,I2ωⅡ =0 .85和I2ωⅢ =0 .41IKDP,三阶非线性系数分别为 χ(3)Ⅰ =1 .60× 1 0 - 1 2 esu ,χ(3)Ⅱ =3.6× 1 0 - 1 2 esu ,χ(3)Ⅲ =1 .2× 1 0 - 1 1 esu .     

Synthesis and shapes of gold nanoparticles by using transition metal monosubstituted heteropolyanions as photocatalysts and stabilizers

Gold nanoparticles were prepared via a simple photoreduction technique in the presence of transition metal monosubstituted Keggin heteropolyanions (PW11M, M= Cu²⁺, Ni²⁺, Zn²⁺, Fe³⁺), in which PW11M acted as reducing agent, photocatalyst and stabilizer. The results indicated that the formation rate and morphology of the nanoparticles strongly depended on the kind of transition metal substituted in heteropolyacid and the preparation conditions, such as irradiation time and propan-2-ol amount. The photoreduction rates of PW11Zn and PW11Fe were faster than those of PW11Ni and PW11Cu. The shapes of the nanoparticles synthesized in the presence of PW11Fe and PW11Zn were nearly uniform spheres, whereas the morphologies of the nanoparticles synthesized in the presence of PW11Ni and PW11Cu were found to contain a mixture of flat triangular/hexagonal structures as well as spheres. Increases in the irradiation time and the propan-2-ol amount could make the morphology of nanoparticles uniform and shorten the formation time of the nanoparticles. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 24(7) (in Chinese)     

V2O5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

Science China Chemistry - A study of the catalytic activity of V2O5/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH...     

Photo-induced ultralong phosphorescence of carbon dots for thermally sensitive dynamic patterning

Stimuli-responsive films with a dynamic long afterglow feature have received considerable attention in the field of optical materials. Herein, we report the unique dynamic ultralong room temperature phosphorescence (URTP) in flexible solid films made of luminescent carbon dots (CDs) and polyvinylpyrrolidone (PVP). Impressively, fully reversible photo-activation and thermal deactivation of the dynamic long afterglow was achieved in this material, with a lifetime on–off ratio exceeding 3900. Subsequently, ultra-fine URTP patterns (resolution > 1280 dpi) with thermally sensitive retention time were readily photo-printed onto the films and utilized as time–temperature indicating logistics labels with multi-editing capacity. These findings not only enrich the library of dynamic URTP materials, but also extend the scope of the potential applications of luminescent CDs.

A flexible CD–polymer composite with a reversibly editable photo-induced URTP long afterglow was rationally designed and successfully applied in dynamic optical patterning with built-in time–temperature indicating functionality.     

A Self-Assembled 3D Hydrogen Bonded Network Constructed from Polyoxovanadate and Protonated Organic Substrate With a Solvent Hydrolysis Reaction

A self-assembled 3D hydrogen bonded network constructed from polyoxovanadate and organic substrate [V₁₀O₂₈][(CH₃)₂NH₂]₄(imidazolium)₂ (1) has been synthesized at room temperature and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The structure of 1 can be regarded as being linked by the dimethylammonium cations of the decavanadate clusters to produce an interesting 3D network with a 4¹²6³ topology. In the resulting network, there exist one-dimensional channels along the a-axis, in which the imidazolium cations filled the channels. These imidazolium cations are involved in intermolecular hydrogen bonds of the types N–H···O and C–H···O, which seem to be main forces to stabilize the holistic structure.