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951.
A simple and facile route is developed for the preparation of mesoporous titanium nitride (TiN) microspheres with a large surface area and a highly porous structure. This method involves the preparation of an amorphous precursor via a solvothermal reaction and subsequent short-time nitridation process to mesoporous TiN. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirm the composition of the resultant sample. The mesoporous structure of the as-prepared TiN sample has been studied by nitrogen adsorption/desorption measurement. The surface area obtained by the Brunauer–Emmett–Teller method is 50.6 m2 g−1 and the pore sizes are in the range of 2.0–4.0 nm. In addition, the obtained sample is evaluated as a new sorbent for Cd2+ removal. Experimental parameters such as solution pH, contact time and concentration of adsorbate are optimized. The maximum adsorption capacity for Cd2+ removal is found to be 12.40 mg g−1 and it is a potentially attractive adsorbent for Cd2+ removal from aqueous solution. 相似文献
952.
In this study, we developed a facile and benign green synthesis approach for the successful fabrication of well-dispersed urchin-like Au@Pt core–shell nanoparticles (NPs) using gallic acid (GA) as both a reducing and protecting agent. The proposed one-step synthesis exploits the differences in the reduction potentials of AuCl4− and PtCl62−, where the AuCl4− ions are preferentially reduced to Au cores and the PtCl62− ions are then deposited continuously onto the Au core surface as a Pt shell. The as-prepared Au@Pt NPs were characterized by transmission electron microscope (TEM); high-resolution transmission electron microscope (HR-TEM); scanning electron microscope (SEM); UV-vis absorption spectra (UV-vis); X-ray diffraction (XRD); Fourier transmission infrared spectra (FT-IR). We systematically investigated the effects of some experimental parameters on the formation of the Au@Pt NPs, i.e., the reaction temperature, the molar ratios of HAuCl4/H2PtCl6, and the amount of GA. When polyvinylpyrrolidone K-30 (PVP) was used as a protecting agent, the Au@Pt core–shell NPs obtained using this green synthesis method were better dispersed and smaller in size. The as-prepared Au@Pt NPs exhibited better catalytic activity in the reaction where NaBH4 reduced p-nitrophenol to p-aminophenol. However, the results showed that the Au@Pt bimetallic NPs had a lower catalytic activity than the pure Au NPs obtained by the same method, which confirmed the formation of Au@Pt core–shell nanostructures because the active sites on the surfaces of the Au NPs were covered with a Pt shell. 相似文献
953.
In this study, we prepared trimanganese tetroxide nanoparticles from MnCl2 solution in an ammonia atmosphere using a new surfactant-free method at room temperature. We analyzed and characterized the effects of different processing conditions, such as the concentrations of manganese and the ammonia source, as well as the reaction time, on the structure, purity, and morphology of the products using powder X-ray diffraction (XRD), scanning electron microscopy, and Fourier transformation infrared spectroscopy (FTIR) techniques. The XRD and FTIR analyses confirmed that the prepared products comprised single phase Mn3O4. At room temperature, the paramagnetic characteristics were also verified by vibrating sample magnetometry. Furthermore, we tested the catalytic activity of the nanoparticles during the degradation of methyl orange and Congo red, which are organic pollutants. Our experiments demonstrated the rapid color removal and reduction in the chemical oxygen demand (>70% and >50% within 10 min, respectively) using aqueous solutions of azo dyes. 相似文献
954.
Piotr Łyżwa Marian Mikołajczyk 《Phosphorus, sulfur, and silicon and the related elements》2014,189(7-8):1174-1192
AbstractAminophosphonic acids have become important in different fields of chemistry, medicine and agriculture. In this review article, we highlight a new strategy developed in the author's laboratory of asymmetric synthesis of enantiomeric aminophosphonic acid that users chiral sulfinimines as reagents. A key reaction in the synthesis of enantiopure α-, β- and γ-aminophosphonic acids is a highly or fully diastereoselective addition of trivalent phosphorus nucleophiles and α-phosphonate carbanions to enantiopure sulfinimines. The steric course of these addition reactions is rationalized. The usefulness of the sulfinimine methodology is demonstrated by the synthesis of biologically active enantiopure 2-amino-3-phosphonopropanoic acid (AP3), 2-amino-4-phosphonobutanoic acid (AP4) and phosphoemeriamine. 相似文献
955.
956.
957.
Two metal–organic frameworks, namely, [Ni2(BIMB)2(ndd)2·H2O]n (1) and [Zn3(ndd)2.5(μ3-OH)(1,3-dpp)]n (2) (H2ndd = 2,2′-(naphthalene-1,5-diylbis(oxy))diacetic acid, BIMB = 1,4-bis[(1H-imidazol-1-ly)methyl]benzene, 1,3-dpp = 1,3-di(pyridin-4-yl)propane) have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. Compound 1 presents a two-dimensional network with point symbol of (36·46·53)-hxl topology. Moreover, compound 2 displays a novel 2-fold interpenetrated structure with the point symbol of (412·63)-pcu topology based on the hexanuclear [Zn6(CO2)10(N)4] unit as a six-connected node. Meanwhile, compound 2 shows good fluorescence property in the solid state at room temperature. 相似文献
958.
Three new metal phosphites, formulated as (H3O)2·Mn2(HPO3)3 (1), Co(bpy) (H2O) (HPO3) (2), and H2tmpda·Zn3(HPO3)4 (3), have been synthesized under solvent-free conditions, where bpy = 4,4′-bipyridine, and tmpda = N,N,N′,N′-tetramethyl-1,3-propanediamine. Compound 1 has a double-layered structure with a thickness of 5.68 Å. Compound 2 has an inorganic-organic hybrid framework with cobalt phosphite layers pillared by bpy ligands. Compound 3 has a three-dimensional open-framework structure containing 8-ring channels. The temperature dependence of the magnetic susceptibility of compounds 1 and 2 were also investigated. 相似文献
959.
Quinones as Dienophiles in the Diels–Alder Reaction: History and Applications in Total Synthesis 下载免费PDF全文
Dr. Christopher C. Nawrat Prof. Dr. Christopher J. Moody 《Angewandte Chemie (International ed. in English)》2014,53(8):2056-2077
In the canon of reactions available to the organic chemist engaged in total synthesis, the Diels–Alder reaction is among the most powerful and well understood. Its ability to rapidly generate molecular complexity through the simultaneous formation of two carbon? carbon bonds is almost unrivalled, and this is reflected in the great number of reported applications of this reaction. Historically, the use of quinones as dienophiles is highly significant, being the very first example investigated by Diels and Alder. Herein, we review the application of the Diels–Alder reaction of quinones in the total synthesis of natural products. The highlighted examples span some 60 years from the landmark syntheses of morphine (1952) and reserpine (1956) by Gates and Woodward, respectively, through to the present day examples, such as the tetracyclines. 相似文献
960.
Dr. Nicholas H. Evans Prof. Paul D. Beer 《Angewandte Chemie (International ed. in English)》2014,53(44):11716-11754
Since the start of this millennium, remarkable progress in the binding and sensing of anions has been taking place, driven in part by discoveries in the use of hydrogen bonding, as well as the previously under‐exploited anion–π interactions and halogen bonding. However, anion supramolecular chemistry has developed substantially beyond anion recognition, and now encompasses a diverse range of disciplines. Dramatic advance has been made in the anion‐templated synthesis of macrocycles and interlocked molecular architectures, while the study of transmembrane anion transporters has flourished from almost nothing into a rapidly maturing field of research. The supramolecular chemistry of anions has also found real practical use in a variety of applications such as catalysis, ion extraction, and the use of anions as stimuli for responsive chemical systems. 相似文献