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991.
Hydrothermal synthesis has afforded a pair of divalent copper acetate coordination polymers containing either 4, 4′‐dipyridylamine (dpa) or 4‐pyridylisonicotinamide (4‐pina), both of which hydrogen‐bonding capable central functional groups. X‐ray crystallography revealed that both exhibit a 1D chain dimensionality. Use of the kinked tethering ligand dpa produced [Cu(OAc)2(dpa)]n ( 1 ), which possesses a simple chain based on dpa linkage of isolated copper ions. On the other hand, employing the straighter amide ligand 4‐pina generated {[Cu(OAc)2(4‐pina)] · 0.5H2O}n ( 2 ), which exhibits {Cu2O2} rhomboid dimers formed through bridging acetate ligands. Weak antiferromagnetic coupling [g = 1.984(3), J = –3.2(3) cm–1] was observed within the axial‐equatorial bridged {Cu2O2} dimers in 2 , with possible ferrimagnetism due to spin canting below 11 K. 相似文献
992.
Lei Guan Yaxu Chen Zhan Shi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1126-1133
AbstractHydrothermal reaction of Zn(NO3)2 · 6?H2O with 2-carboxyethyl(phenyl)phosphinate (H2L) and 4,4'-bipyridine (4,4′-bipy) led to a novel zinc(II) carboxyphosphinate [ZnL(4,4′-bipy)0.5]n (1). The zinc ion is tetrahedrally coordinated by two phosphinate oxygen atoms, one carboxylate oxygen atom, and one nitrogen atom of 4,4′-bipy ligand. The L2- ligand and zinc ion can be seen as three- and four-connected nodes, respectively. Compound 1 shows a layered network with (3,4)-connected topology. It exhibits a broad blue fluorescent emission band at 459?nm, which can be attributed to 4,4′-bipy intraligand emission as well as to H2L emission. It is a diamagnetic system between 300?K and 11?K. 相似文献
993.
利用简单的水热法以及后续热处理, 将钴酸镍纳米花成功生长在活性炭纤维支架上. 场发射扫描电镜(FESEM)及透射电镜(TEM)结果表明, 纳米花是由纳米针自组装而成, 而纳米针呈多孔结构. 这种三维复合多级结构非常有利于电解质离子的渗透和电子的传输. 将该多孔钴酸镍纳米花/活性炭纤维布作为工作电极, 表现出优良的电容性能. 在1 A·g-1时, 比电容高达1626 F·g-1; 在10 A·g-1时, 电容保持率为65%, 具有超高的电容值和优异的倍率特性. 相似文献
994.
[M(2,2'–bpy)2]2SiW12O40(M=Mn,Co;bpy=联吡啶)的合成、结构及其电催化水产氧性能 总被引:1,自引:0,他引:1
用水热法合成了过渡金属联吡啶配阳离子硅钨杂多酸:[M(2,2’-bpy)2]2SiW12O40(M=Mn(1)和M=Co(2)),采用红外光谱、元素分析、热重和单晶X射线衍射对其进行了表征。结果表明,化合物1和2是异质同构体,具有二维格子框架结构。初步研究了2种化合物的电催化H2O析出O2性能,发现化合物1对电催化H2O析出O2有一定的催化作用。 相似文献
995.
Yu-Ting Wang Xiao-Qing Shen Hong-Chang Yao Hong-Wei Hou 《Supramolecular chemistry》2013,25(5):501-515
Seven new metal-organic coordination polymers, [M(tzda)(H2O)4] n [M = Co(1), Ni (2) and Zn(3)], [Zn(tzda)(4,4′-bipy)] n (4), [Cd(tzda)(4,4′-bipy)0.5(H2O)] n (5) and [M(tzda)(4,4′-bipy)(H2O)] n [M = Co(6), Ni(7)] [H2tzda = (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally synthesized and structurally characterized by X-ray single crystal diffraction. Compounds 1–3 display similar 1D zigzag chain structure. Compound 4 possesses a 2D-layered architecture generated from [Zn(tzda)] n moiety with double-chain structure cross-linking 4,4′-bipy spacers, while compound 5 consists of –Cd–OCO–Cd–OCO– chains cross-linked through –CH2SC2N2SSCH2– spacers of tzda anions and 4,4′-bipy, also showing a 2D-layered structure. The structures of 6 and 7 seem more complicated, in which the [M(tzda)] n layered subunits are extended to unique 3D framework by the bridging 4,4′-bipy ligand. Photoluminescence investigations reveal that 4 and 5 both display strong blue emissions in the solid state at room temperature, which could be significant in the field of luminescent materials. The magnetic studies of 6 and 7 show both display the characteristics of a weak antiferromagnetic coupling between metal ions in the system mediated by carboxylate bridges. 相似文献
996.
At mild hydrothermal conditions triclinic modifications of BaMP2O7 (M = Mn and/or Cu) have been succeeded. The method offers cheap, one step, impurity free and chemical flexible fabrication of family of metal phosphates that are potential low-dimensional quantum magnets. Partial isomorphous substitution of the Mn2+ by Cu2+ resulted into mixed-metal solid that has been structurally and magnetically characterized. Rietveld refinement study confirmed the structures and revealed the influence of transition metal substitution. The temperature-dependent magnetic measurements revealed that the system is paramagnetic in almost all temperature range and an apparent antiferromagnetic phase transition occurs around 5 K. Using the Curie–Weiss law, a Curie–Weiss temperature, θP = −11.0 K, and a Curie constant C = 3.39 emu K mol−1 was obtained. The small negative θP value and the χT behavior as a function of temperature reveal a weak antiferromagnetic interaction between the Cu2+/Mn2+magnetic centers. 相似文献
997.
《中国化学快报》2020,31(12):3200-3204
Li2FeTiO4 composites have been produced using commercial LiAC, FeCl2 and different titanium sources by hydrothermal synthesis (HS) at 175 °C and subsequent annealing at 700 °C. Impure phase TiO2, Fe2O3 and FeTiO4 were detected out among the Li2FeTiO4 composites with different titanium sources. Micron and nano-sized particles of Li2FeTiO4 were prepared from various titanium raw materials, with nano-sized particles predominating when titanium raw materials were layered hydrogen titanate nanowire (H2Ti3O7NW, HTO-NW) and titanium oxide nanotubes (TiO2NB). The Li2FeTiO4 composites synthesized by HTO-NW shows a primary particle size of 50−200 nm of high crystallinity staggered with undissolved nanowire with a diameter size of about 100 nm. The samples using one-dimensional nanometer titanium oxide (TiO2 NB) as the raw material can get a super high initial discharge capacity of 367.8 mAh/g at the rate of C/10 and excellent cycling stability. The selection of raw materials and adopting multi-phase modification can be considered as an effective strategy to improve the electro-chemical properties of Li2FeTiO4 composite cathode materials for the lithium secondary battery. 相似文献
998.
《中国化学快报》2020,31(8):2083-2086
Using SnSO4, d-glucose, urea and water, hierarchical shell-core SnO2 microspheres were successfully synthesized via a simple hydrothermal method. The characterization results showed that the sizes of as-prepared SnO2 microspheres were 0.6–1 μm, with shell thicknesses of 40−60 nm. The shell and large core of the SnO2 microspheres were all comprised of the same basic rice-like nanoparticles with diameters of 16−25 nm and lengths of 16−45 nm. Further investigaton showed that the glucose and urea served as structural guiding agents, and urea facilitated the formation of the hierarchical structure. The as-prepared SnO2 nanomaterials were used to fabricate a gas sensor with an electrode blade used for the gas sensitivity tests. The hierarchical shell-core SnO2 microspheres exhibited high sensitivity and selectivity toward ethanol, with a responsivity of 63.8 for 50 ppm ethanol at 250 °C, while the response and recovery time were 7 s and 28 s respectively. Moreover, the responsivity of the materials showed good linearity at ethanol concentrations from 500 ppb to 10 ppm. The simple synthetic method, environmentally-friendly raw materials, and excellent gas sensitivity demonstrate that the as-prepared SnO2 nanomaterial has great potential applications for the sensing of ethanol gas. 相似文献
999.
Heteroatom‐doped carbon materials have been widely used in energy storage and conversion such as supercapacitors and electrocatalysts. In this work, L‐asparagine (Asn), an amino acid derivative, has been used as a doping agent to prepare nitrogen‐ doped reduced graphene oxide gels (N‐GAs). The 3D interconnected structure gives rise to the superior electrochemical properties for supercapacitor and electrocatalytic oxygen reduction reaction (ORR). The N‐GA‐4 (the mass ratio of Asn to graphene oxide (GO) is 4 : 1 by hydrothermal method) electrode shows the capacitance of 291.6 F·g–1 at 0.5 A·g–1. Meanwhile, the assembled symmetric supercapacitor achieves a maximum energy density of 23.8 Wh· kg–1 when the power density is 451.2 W·kg–1, and demonstrates an ultralong cycling life that the retention of capacitance is 99.3% after 80000 cycles. What's more, the annealed aerogel N‐GA‐4‐900 exhibits an onset potential (Eonset) of 0.95 V, half wave potential (E1/2) of 0.84 V (vs. RHE) and the oxygen reduction current density of 5.5 mA·cm–2 at 0.1 V with nearly four‐electron transfer, which are superior to commercial Pt/C. This work offers a new insight into the synthesis and applications of N‐GAs materials towards high performance in supercapacitors and ORR. 相似文献
1000.
通过水热合成得到石榴石型铁氧体材料Nd3-xSrxFe5O12(x=0.2,0.4,0.6,0.8),经X射线粉末衍射分析确定样品属于立方晶系,Ia3d空间群,晶格常数a>1.2600 nm.Mssbauer谱数据显示Sr2+离子和Nd3+离子共同占据十二面体C位,晶格中有少量Fe4+离子生成.通过扫描电子显微镜观察到样品晶粒为菱形十二面体.高温M-T曲线和磁滞回线表明,4个样品的居里温度均在570 K左右,不因Sr2+离子含量不同而改变;但是随着Sr2+离子在晶格中含量的增加,样品的饱和磁化强度(Ms)下降,矫顽力(Hc)增大. 相似文献