Synthesis and UV shielding properties of zinc oxide ultrafine particles modified with silica and trimethyl siloxane

This paper introduces a kind of ZnO ultrafine particles modified with silica and trimethyl siloxane (TMS). Thus zinc carbonate hydroxide (ZCH) as the precursor of ZnO was synthesized using chemical precipitation method, and the precursor was modified in situ with silica and TMS. The modified ZnO ultrafine particles were obtained after calcinating the modified precursors. The surface properties of the modified ZnO ultrafine particles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectra (XPS), scanning electron microscope (SEM), and transmission electron microscopy (TEM). The effects of the modifiers on the photocatalytic activity and UV shielding ability of ZnO ultrafine particles were also investigated and discussed.     

Emissive Iridium(III) Complexes with Phosphorous‐Containing Ancillary

Ir(III) metal complexes and related emitters bearing all kind of cyclometalated chromophoric chelates and non‐chromophoric ancillary are extensively studied during the past three decades. Many of them have been found to display bright room temperature phosphorescence from triplet excited states in both solution and solid states, offering a possible application in contemporary optoelectronic technologies, including organic light emitting diodes, electrochemiluminescence, biological imaging and chemical sensing. Among reported materials, there are Ir(III) complexes with at least one phosphorus (P)‐containing ligand and/or ancillary chelate, together with cyclometalates or equivalents that are in control of the actual emission energy. Particularly, possession of P‐based donor can lead to divergent structural and photophysical properties compared to the traditional designs. This review aims to provide a literature overview as well as the authors’ personal account to the development of relevant Ir(III) based phosphors bearing these P‐donors. To the readers’ convenience, the contents are subdivided into six sessions, according to whether or not they are charge natural, or with mono‐ or dianionic electronic character, and in accordance to their divergent bonding modes, i. e. monodentate, bidentate and tripodal coordination. In many cases, the P‐based ancillaries offer an easy accessible route to the formation of efficient sky‐blue and true‐blue emitters due to their π‐accepting property, together with enlarged emission energy gap and destabilized upper lying quenching state.     

Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products

The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.     

Synthesis and characterization of fluorine-containing polyamides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane by direct polycondensation

A fluorine-containing diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BAPPH) ( II ), was synthesized in two steps on condensation of 2,2-bis(4-hydroxyphenyl)hexafluoropropane with p-chloronitrobenzene in the presence of potassium carbonate, giving 2,2-bis[4-(4-nitrophenoxy)phenyl]hexafluoropropane ( I ), followed by reduction with hydrazine monohydrate/Pd—C. Fluorine-containing polyamides and copolyamides having inherent viscosities 0.41–0.88 dL g⁻¹ were prepared by direct polycondensation of BAPPH with various aromatic diacids or with mixed diacids, by triphenyl phosphite and pyridine in N-methyl-2-pyrrolidinone (NMP). The polyamides were examined by elemental analysis, IR spectra, inherent viscosity, x-ray diffraction, solubility, DSC, and TGA. The diffractogram showed that the polyamides were crystalline except IVb , IVc , IVf , and Vc . Almost all polyamides were soluble in polar aprotic solvents. The polymers obtained from BAPPH lost no mass below 350°C, with 10% loss of mass being recorded above 467°C in nitrogen. These aromatic polyamides had glass transition temperatures in the 221–253°C range. © 1996 John Wiley & Sons, Inc.     

新型三维结构亚磷酸钒(Ⅲ)[V2(HPO3)3·(H2O)3]·H2O的水热合成与晶体结构

在具有开放骨架结构的过渡金属磷酸盐微孔材料的合成中，钒磷酸盐因在催化和磁学方面具有潜在的性质和特殊结构特征而引起人们的广泛兴趣．近年来，人们正在尝试用假四面体结构的[HPO3]^2-替代四面体结构的[PO4]^3-，因为{HPO3}结构基元同钒原子的连接方式与{PO4}结构基元和钒原子的连接方式具有明显的差别，     

An infrared spectroscopic investigation of thin alumina films: measurement of acid sites and surface reactivity

The surface chemical activity of an alumina films grown on Mo(100) by oxidation of aluminum evaporated onto the surface and oxidized using water is examined using Auger, X-ray photoelectron and reflection/absorption infrared spectroscopies. The formation of alumina is confirmed using Auger and X-ray photoelectron spectroscopy from the positions and intensities of the aluminum features and using reflection-absorption infrared spectroscopy from the longitudinal optical modes of the Al–O bonds measured at 935 cm⁻¹. The presence of surface hydroxyls is monitored by forming films using D₂O which are evidenced by a feature at 2700 cm⁻¹. Ammonia adsorption on a dehydroxylated surface yields a single peak at 1260 cm⁻¹ due to ammonia adsorbed at a surface Lewis site where the principle symmetry axis of ammonia is oriented perpendicularly to the surface plane. Ammonia also appears to adsorb at Lewis sites on a hydroxylated surface with a slightly different adsorption geometry from that on a dehydroxylated surface. Finally, the chemistry of trimethyl aluminum adsorbed on the planar hydroxylated alumina surface is compared with that found on high-surface-area γ-alumina where the spectra and the chemistry found in both régimes is exactly identical except that the low-frequency methyl bending modes (at 769 and 718 cm⁻¹) are not obscured on the thin film by the intense substrate whereas they are on the high-surface-area support.     

Synthesis and properties of poly(imide‐hydrazide)s and poly(amide‐imide‐hydrazide)s from N‐[p‐(or m‐)carboxyphenyl]trimellitimide and aromatic dihydrazides or p‐aminobenzhydrazide via the phosphorylation reaction

A series of new poly(imide‐hydrazide)s and poly(amide‐imide‐hydrazide)s were obtained by the direct polycondensation of N‐[p‐(or m‐)carboxyphenyl]trimellitimide (p‐ or m‐CPTMI) with terephthalic dihydrazide (TPH), isophthalic dihydrazide (IPH), and p‐aminobenzhydrazide (p‐ABH) by means of diphenyl phosphite and pyridine in the N‐methyl‐2‐pyrrolidone (NMP) solutions containing dissolved CaCl₂. The resulting hydrazide‐containing polymers exhibited inherent viscosities in the 0.15–0.96 dL/g range. Except for that derived from p‐CPTMI with TPH or p‐ABH, the other hydrazide copolymers were readily soluble in polar solvents such as NMP and dimethyl sulfoxide (DMSO). As evidenced by X‐ray diffraction patterns, the hydrazide copolymer obtained from TPH showed a moderate level of crystallinity, whereas the others were amorphous in nature. Most of the amorphous hydrazide copolymers formed flexible and tough films by solvent casting. The amorphous hydrazide copolymers had glass‐transition temperatures (T_g) between 187 and 233 °C. All hydrazide copolymers could be thermally converted into the corresponding oxadiazole copolymers approximately in the region of 250–400 °C, as evidenced by the DSC thermograms. The oxadiazole copolymers showed a significantly decreased solubility when compared to their respective hydrazide precursors. They exhibited T_g's of 264–302 °C and did not show dramatic weight loss before 400 °C in air or nitrogen. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1599–1608, 2000     

9个PstI接头片段的合成及其酶反应研究

采用固相亚磷酸三酯法和化学与酶促相结合的方法合成了９个ＰｓｔＩ接头片段，并对它们进行了酶切反应研究．结果表明：ＰｓｔＩ识别序列中尿苷的存在只降低其互补链的切割程度，对其本链没有影响；ＰｓｔＩ切割底物是按两步单股切割机制进行，作用的最小底物是含有识别序列的８～１２聚脱氧核糖核苷酸，且对底物中识别序列两边的碱基对数目有一定要求；ＰｓｔＩ识别序列中的二个胞苷在酶反应中起的作用是不一样的     

New poly(amide-imide) syntheses. XII. Preparation and properties of poly(amide-imide)s based on the diimide-diacid condensed from 9,9-bis[4-(4-aminophenoxy)phenyl] fluorene and trimellitic anhydride

A dicarboxylic acid ( I ) was prepared from the condensation of 9,9-bis[4-(4-aminophenoxy) phenyl] fluorene and trimellitic anhydride. A new family of poly(amide-imide)s having inherent viscosities of 0.75-1.04 dL/g was prepared by the triphenyl phosphite activated polycondensation from the diimide-diacid I with various aromatic diamines in a medium consisting of N-methyl-2-pyrrolidone (NMP), pyridine, and calcium chloride. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N,N-dimethylacetamide. All the soluble poly(amide-imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 262–325°C and the 10% weight loss temperatures were above 525°C in air. © 1994 John Wiley & Sons, Inc.     

磷酸三甲酯三（磷酸二甲酯）合镧的合成与结构研究

(RO)_2PO_2H型酸性磷酸醋由于含有多个可与金属配位的氧原子,可以和金属离子形成多种形式且结构特殊的配合物。作为一类重要的萃取剂,对酸性磷酸酯配合物的研究有助于了解萃取的规律和机理。虽然这类配合物的合成及结构已有报道,但最基本的磷酸二甲酯与金属离子配合物的结构未见报道。本工作首次合成了标题化合物,测定了它的红外光谱和单晶结构。现将结果简报如下。