Spectroscopic calculation of CH bond dissociation energies for the bromo derivatives of alkanes,alkenes, and arenes

The CH bond dissociation energies were determined for the bromo derivatives of methane, ethane, propane, cyclopropane, ethane, propene, and benzene by the spectroscopic and quantum-chemical methods. The spectroscopic values of the CH bond dissociation energies were obtained from the fundamental absorption bands by the variational method in an anharmonic approximation using the Morse-harmonic basis. Quantum-chemical calculations were performed using the 6-311G(3df, 3pd)/B3LYP basis. The resulting tendencies of variation of the bond dissociation energies due to changes in the molecular structure are discussed.     

Mercury thiocyanate coordination polymers generated from rigid or flexible organic nitrogen donor-based ligands

Four mercury(II) thiocyanate–organic polymeric complexes, [Hg(μ-4,4-bipy)(SCN)₂]_n (1), [Hg(μ-bpa)(SCN)₂]_n (2), [Hg(μ-bpe)(SCN)₂]_n (3), [Hg(μ-bpp)(SCN)₂]_n (4) {4,4-bipy = 4,4′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethene and bpp = 1,3-di(4-pyridyl)propane} were prepared from reactions of mercury(II) thiocyanate with four rigid and flexible organic nitrogen donor-based ligands under thermal gradient conditions, brunched tube method. All these compounds were structurally determined by X-ray single-crystal diffraction. The thermal stabilities of compounds 1–4 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Solid state luminescent spectra of compounds 1 and 3 indicate intense fluorescent emissions at 430 and 468 nm, respectively.     

基于联苯四羧酸的Zn(Ⅱ)配合物的合成、结构和性质

利用联苯四羧酸(H4bptc)和双三唑乙烷(bte)合成了2个配位聚合物{[Zn2(bptc)(DMF)2(H2O)]·DMF·H2O}n(1)和{[Zn(bte)(bptc)0.5]·DMF·0.5H2O}n(2)。化合物1为三维Pt S-拓扑结构,在该配合物中每个双核次级构筑单元(SBU){Zn2(O2CR)4}与4个联苯四酸配体相连,从而将配合物构筑成了三维MOF结构。化合物2为二维梯形结构,并通过弱氢键O…H-C将二维层连接为三维结构。同时对配合物的热稳定性和荧光特征进行了讨论。     

Identifying Different Types of Catalysts for CO2 Reduction by Ethane through Dry Reforming and Oxidative Dehydrogenation

The recent shale gas boom combined with the requirement to reduce atmospheric CO₂ have created an opportunity for using both raw materials (shale gas and CO₂) in a single process. Shale gas is primarily made up of methane, but ethane comprises about 10 % and reserves are underutilized. Two routes have been investigated by combining ethane decomposition with CO₂ reduction to produce products of higher value. The first reaction is ethane dry reforming which produces synthesis gas (CO+H₂). The second route is oxidative dehydrogenation which produces ethylene using CO₂ as a soft oxidant. The results of this study indicate that the Pt/CeO₂ catalyst shows promise for the production of synthesis gas, while Mo₂C‐based materials preserve the C? C bond of ethane to produce ethylene. These findings are supported by density functional theory (DFT) calculations and X‐ray absorption near‐edge spectroscopy (XANES) characterization of the catalysts under in situ reaction conditions.     

Synthesis,structure, and antioxidative properties of a copper(II) complex with 1,2-bis(benzimidazol-2-yl)ethane ligand

1,2-Bis(benzimidazol-2-yl)ethane (bbe) and its copper(II) complex, {[Cu(bbe)Br₂]₂}·2DMF ( 1 ), have been synthesized and characterized by elemental analysis, ultraviolet–visible, and infrared spectra. The single crystal structure analysis of 1 shows two crystallographically independent but chemically identical [Cu(bbe)Br₂] molecules. The coordination geometry of the copper atoms may best be described as a distorted tetrahedron (τ₄ = 0.740 for Cu1 and 0.696 for Cu2). The cyclic voltammogram of complex 1 represents quasi-reversible Cu²⁺/Cu⁺ pairs. in vitro antioxidant tests showed that complex 1 has significant antioxidant activity against superoxide and hydroxy radicals. Photoluminescence investigations showed that the fluorescence intensity of complex 1 is significantly weaker than that of the ligand. This may be due to the paramagnetic effect of divalent copper to cause quenching of fluorescence.     

Syntheses and characterization of energetic compounds constructed from alkaline earth metal cations (Sr and Ba) and 1,2-bis(tetrazol-5-yl)ethane

Two new energetic compounds, [M(BTE)(H₂O)₅]_n (M=Sr(1), Ba(2)) [H₂BTE=1,2-bis(tetrazol-5-yl)ethane], have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that they are isomorphous and exhibit 2D (4,4) net framework, generated by 4-connected Sr₂(H₂O)₁₀/Ba₂(H₂O)₁₀ SBUs linked up by two independent binding modes of H₂BTE, and the resulting 2D structure is interconnected by hydrogen-bond and strong face to face π-π stacking interactions between two tetrazole rings to lead to a 3D supramolecular architecture. DSC measurements show that they have significant catalytic effects on thermal decomposition of ammonium perchlorate. Moreover, the photoluminescence properties, thermogravimetric analyses, and flame colors of the as-prepared compounds are also investigated in this paper.     

“Wheel-and-axle” binuclear Cu(II) dioximates mediated by 1,2-bis(4-pyridyl)ethane: Synthesis, X-ray study and luminescent properties

The reaction of copper(II) acetate or fluoride with classic dioximes in the presence of 1,2-bis(4-pyridyl)ethane resulted in four novel compounds with the compositions [Cu₂(dmgH)₄bpe] (1), [Cu₂(NioxH)₄bpe] (2), [Cu₂(dpgH)₄bpe] (3), and [Cu₂(dpgH)₄bpe][Cu(dpgH)₂bpe]₂·2DMF (4) (where dmgH₂ = dimethylglyoxime, NioxH₂ = 1,2-cyclohexanedionedioxime, dpgH₂ = diphenylglyoxime, bpe = 1,2-bis(4-pyridyl)ethane, and DMF = N,N′-dimethylformamide), whose crystal structures were determined by single crystal X-ray diffraction. In the binuclear molecules 1-3, as well as in both binuclear and mononuclear molecules in 4 each Cu(II) atom has an identical N₅-environment formulated by four oximic nitrogen atoms of two monodeprotonated ligands in a slightly distorted square planar mode, and the nitrogen atom of the bpe molecule being in the apical position. The new compounds were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Luminescence investigations for 1, 2 and 4 were carried out to clarify whether the guest inclusion in the crystal lattice is accompanied by changes in the emission spectra.     

气相色谱-质谱法测定橡胶和塑料制品中十溴二苯乙烷

建立了气相色谱-质谱联用仪测定橡胶和塑料制品中十溴二苯乙烷(DBDPE)的方法。以甲苯为提取溶剂,分离净化,采用气相色谱-质谱法(GC/MS)检测。结果表明:DBDPE的线性关系、检出限、回收率和精密度都较好,回收率在75.7%～102.2%之间,相对标准偏差小于10%,方法检出限为1 mg/kg。本方法适用于塑料和橡胶制品中DBDPE的测定。     

Copper(II) coordination polymers constructed from aromatic polycarboxylate and flexible triazole ligands with different spacer lengths: syntheses,structures, and properties

{[Cu₂(btm)₂(Hbtc)(H₂btc)₂(H₂O)]·9.5H₂O}_n (1), [Cu(bte)(H₂btc)₂]_n (2) {[Cu(btp)(H₂btc)₂]·0.25H₂O}_n (3) (btm?=?bis(1,2,4-triazol-1-yl)methane, bte?=?bis(1,2,4-triazol-1-yl)ethane, btp?=?bis(1,2,4-triazol-1-yl)propane, H₃btc?=?benzene-1, 3, 5-tricarboxylic acid) have been synthesized and structurally characterized. 1 features a 1-D double chain, which is interconnected by classical hydrogen-bonding (O–H?O) and π–π interactions to lead to a 3-D supramolecular architecture. 2 and 3 are both 1-D single chains, which are interconnected by π–π interactions to 2-D layer architectures. Elemental analysis, XRD, IR, TG and EPR spectra have been carried out and discussed.     

Photochemical reactions of metal carbonyls [M(CO)6 (M=Cr,Mo, W)] with N,N′ -bis(salicylidene)-1,2-bis- ( o -aminophenoxy)ethane

The complexes [M(CO)₄(η²-H₂L)] [M?=?Cr; 1, Mo; 2, W; 3] have been synthesized by photochemical reactions of VIB metal carbonyls [M(CO)₆] [M?=?Cr,?Mo,?W] with N,N′-bis(salicylidene)-1,2-bis-(o-aminophenoxy)ethane (H₂L) in THF and characterized by elemental analyses, FTIR, ¹H?NMR and mass spectra. The H₂L ligand is coordinated to the central metal as a bidentate ligand via the central azomethine nitrogen atoms in 1–3.