Zirconium scandium oxide nitrides: Formation and decomposition followed in situ by XRD and thermal analysis

The dark green powder of Zr₅₀Sc₁₂O₄₃N₅₀ was produced from Zr₅₀Sc₁₂O₁₁₈ under a constant flow of ammonia. Zr₅₀Sc₁₂O₄₃N₅₀ crystallizes cubic with space group and in the C-M₂O₃ structure (bixbyite structure). The reaction path was followed by in situ X-ray diffraction and showed that the substitution of 3O²⁻ by 2N³⁻ generates additional vacancies on the anion sites in the fluorite basis structure. On the way to the bixbyite structure time- and temperature-controlled X-ray diffractograms revealed the known fluorite-related superstructures (i.e. the vacancy distribution) for the compositions M₁₄X₂₆ and M₇X₁₂. The reverse process, i.e. the oxidation of the oxide nitride was followed in DTA/TG experiments exhibiting the different vacancy orderings at 420, 500 and .     

Tertiary-Amine-Initiated Synthesis of Acyl Fluorides from Carboxylic Acids and CF3SO2OCF3

A convenient method for deoxyfluorination of aromatic and aliphatic carboxylic acids with CF₃SO₂OCF₃ in the presence of a suitable base at room temperature has been developed. The reaction allows a straightforward access to a variety of acyl fluorides and proves that CF₃SO₂OCF₃ is an effective deoxyfluorination reagent for carboxylic acids. The method features simplicity, expeditiousness, high efficiency, ease of handling, good functional group tolerance, a wide range of substrates, excellent yields of products, compatibility of many amine initiators, use of environmentally friendly reagents, and effortless removal of byproducts. This reaction represents the first utilization of trifluoromethyl trifluoromethanesulfonate as a fluorination reagent.     

Structure of ScBr3 and Sc2Br6 molecules determined by the synchronous gas-phase electron diffraction and mass spectrometric experiment and quantum chemical calculations

The structure of monomeric and dimeric molecules of scandium tribromide is studied by the synchronous electron diffraction and mass spectrometric experiment at T = 888(10) K and also by the quantum chemical calculations. The experimental data on the structural parameters of ScBr₃ molecule were obtained for the first time; also for the first time the molecular structure of Sc₂Br₆ dimeric molecule was studied. It is found that the ScBr₃ molecule has the C _3v effective configuration with the distance r _g (Sc-Br) = 2.430(3) Å and the valence angle ∠_g(Br-Sc-Br) = 117.6(5)°. The equilibrium structure of the given molecule is planar with D _3h symmetry. According to a theoretical study by DFT and MP2 methods, Sc₂Br₆ molecule has the equilibrium structure of D _2h symmetry with four Sc-Br bridge bonds. It was confirmed by the results of the electron diffraction analysis.     

15N同位素标记的金属氮化物内嵌富勒烯的合成与表征

利用电弧放电法制备了¹⁵N同位素标记的金属氮化物内嵌富勒烯. 制备过程中使用¹⁵NH₄Cl作为固体氮源, 基于电弧放电方法在氦气气氛中将石墨、金属钪和¹⁵NH₄Cl高温原子化, 合成得到Sc₃¹⁵N@C₈₀和Sc₃¹⁵N@C₇₈. 利用高效液相色谱法进行分离纯化, 并通过质谱、紫外可见吸收光谱和核磁共振碳谱表征了Sc₃¹⁵N@C₈₀, 验证了¹⁵N的成功标记, 还表明合成的Sc₃¹⁵N@C₈₀具有I_h-C₈₀碳笼. 所制备的¹⁵N标记的金属氮化物内嵌富勒烯中含有98%以上的¹⁵N同位素, 将拓展金属富勒烯材料在同位素示踪等领域的应用.     

单分散共价有机框架纳米颗粒的室温快速制备

以稀土金属三氟甲磺酸盐作为新型的共价有机框架(COF)合成催化剂,成功制备了 4种不同结构的COF(COF-42、TPBDMTP、RT-COF-1、COF-LZU1)的单分散纳米级颗粒,并通过对反应条件的系统性调控,实现200～900 nm范围内精确控制COF的粒径。X射线衍射表征证明了产物良好的结晶性。此外,相较于传统的水热合成,该方法可在室温常压条件下操作,并且在0.5 h内快速得到产物。     

Polymer fibers as carriers for homogeneous catalysts

This paper describes a polymer fiber-based approach for the immobilization of homogeneous catalysts. The goal is to generate products that are free of catalysts which would be of great importance for the development of optoelectronic or pharmaceutical compounds. Electrospinning was employed to prepare the non-woven fiber assembly composed of polystyrene. The homogeneous catalyst scandium triflate was immobilized on the polystyrene fibers during electrospinning and on corresponding core shell fibers using a fiber template approach. An imino aldol and an aza-Diels-Alder model reaction were carried out with each fibrous catalytic system. This resulted in the immobilization of homogeneous catalysts in a polymer environment without loss of their catalytic activity and may even be enhanced when compared with reactions carried out in homogeneous solutions.     

离子色谱法同时分析离子液体中三氟乙酸根、四氟硼酸根和三氟甲烷磺酸根

建立了离子色谱-直接电导检测法同时测定离子液体中三氟乙酸根、四氟硼酸根和三氟甲烷磺酸根的方法。色谱分离采用Shim-packIC-A3阴离子交换色谱柱和邻苯二甲酸氢钾淋洗液。最佳色谱条件为:以邻苯二甲酸氢钾(1.2mmol/L)为淋洗液,柱温30℃,流速1.0mL/min。在此条件下,所测阴离子的检出限为0.06～3.07mg/L,保留时间和峰面积的相对标准偏差(n=5)分别不大于0.18%和1.62%。用来测定离子液体中三氟乙酸根、四氟硼酸根和三氟甲烷磺酸根,加标回收率为98.2%～101.8%,能够满足离子液体中的三氟乙酸根、四氟硼酸根和三氟甲烷磺酸根定量分析要求。     

Protonation equilibria of nitrilotris(methylenephosphonato)-and ethylenediamine-tetrakis(methylenephosphonato)-complexes of scandium,yttrium, and lanthanoids

The protonation equilibria of nitrilotris(methylenephosphonic acid) (NTMP, H₆L) and ethylenediaminetetrakis(methylenephosphonic acid) (EDTMP, H₈L) complexes of scandium, yttrium, and lanthanoids have been studied potentiometrically at 25°C and at an ionic strength of 0.1 mol-dm^–3 KNO₃. The first protonation constants of NTMP complexes of lanthanoids, K _MHL , decrease with decreasing of the ionic radius of the lanthanoid [log K _MHL =7.82 (La³⁺) –6.90 (Lu³⁺)] and show a so-called Tetrad effect. The second protonation constants, K _{MH 2}L, change very little with the lanthanoid metal ions (logK _{MH 2}L=5.3–5.7). These results suggest that, in the first protonation process in ML, the proton attacks the nitrogen of NTMP rupturing the M-N of M(ntmp)^3–. The pattern of the change in the protonation constants of the EDTMP complexes with the atomic number of the lanthanoid is quite different from that of the NTMP complexes. This fact indicates that the manner of protonation of the EDTMP complexes differs from that of NTMP complexes. The protonation constants of yttrium complexes of NTMP and EDTMP agree with those of lanthanoid complexes, whereas those of scandium complexes deviate from the values predicted from its ionic radius.