Thermal investigation of iron(III) and manganese(II,III) complexes of dianils derived from 6-formylkhellin

Manganese and iron complexes of Schiff bases derived from 6-formylkhellin were prepared and characterized. Complexes of o-phenylenediamine derivative (ligand (I)) are monomeric or dimeric whereas those of p-phenylenediamine derivative (ligand (II)) are polymeric. The complexes obtained are characterized by a lower magnetic moment values. The complexes also have different solvent of crystallization with different nature of interaction. The thermal behaviour of the ligands and their metal complexes was investigated by means of DTA, TG, IR and X-ray diffraction spectroscopy. Ligand (I) shows different thermal behaviour from that of ligands (II) and (III). The complexes of ligand (II) give abnormal oxides as a final product during their thermal decomposition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Novel determination of the dimerization mechanism for thermal polymerization of α-methylstyrene

This study discussed the phenomena on thermal polymerization of α-methylstyrene (AMS). A curve scanned by temperature-programmed technique was performed by differential scanning calorimetry (DSC). Heat of polymerization (ΔH) and onset temperature of exothermic (T₀) behavior were determined to be 280±10 J g^-1 and about 138±1°C, respectively. A dimer formation mechanism was proposed for initiation of the propagating chain. Spectroscopic identification of dimer structure was conducted by infrared (IR) spectroscopy in the wavenumber from 650 to 1100 cm^-1associated with molecular fingerprint characteristics. The mechanism of thermal polymerization on α-methylstyrene proposed in this study was similar to that of styrene suggested by Mayo.     

Zur Kenntnis der Hydrate M(HSeO3)2 · 4H2O (M = Mg,Co, Ni,Zn). Röntgenstrukturanalytische,schwingungsspektroskopische und thermoanalytische Untersuchungen

On the Hydrates M(HSeO₃)₂ · 4H₂O (M = Mg, Co, Ni, Zn) – Crystal Structures, IR, Raman, and Thermoanalytical Investigations From aqueous solutions of M(HSeO₃)₂ single crystals of Mg(HSeO₃)₂ · 4H₂O and of the hitherto unknown compounds Co(HSeO₃)₂ · 4H₂O, Ni(HSeO₃)₂ · 4H₂O and Zn(HSeO₃)₂ · 4H₂O could be obtained. The crystal structures, X-ray powder, IR, Raman and thermoanalytical (DTA, TG, Raman heating) data are presented and discussed. The crystal data of the isotypic compounds are: monoclinic, space group C2/c, Z = 4, Mg: a = 1 464.6(2), b = 755.3(1), c = 1 099.9(1) pm, β = 126.59(1)°, V = 0.9769(1) nm³, Co: a = 1 462.5(2), b = 756.5(2), c = 1 102.2(2) pm, β = 126.53(1)°, V = 0.9798(2) nm³, Ni: a = 1 452.2(2), b = 751.0(1), c = 1 091.5(1) pm, β = 126.28(1)°, V = 0.9595(1) nm³, Zn: a = 1 468.3(2), b = 755.8(1), c = 1 103.1(1) pm, β = 126.79(1)°, V = 0.9804(2) nm³. The crystal structures consist of hexagonal packed [M(HSeO₃)₂ · 2H₂O]_n chains of [MO₄(H₂O)₂] octahedra linked by Se atoms. They contain trigonal pyramidal SeO₂OH^?ions with “free” hydroxyl groups and also “free” molecules of water of crystallization. The hydroxyl groups build strong H-bonds (O? H …? O distances: 265–268 pm). The IR spectra show AB doublett bands in the OH stretching mode region of the hydroxyl groups. The water molecules of crystallization are linked to planar (H₂O)₄ tetramers by H-bonds with unusually short O? H …? O bond distances of 271–273 pm. DTA and TG measurements indicate that thermal decomposition results in the direct formation of the respective diselenite MSe₂O₅. Raman heating measurements show under quasi static conditions the intermediate formation of the anhydrous hydrogen selenites.     

磷脂酰胆碱与牛血清白蛋白相互作用的FT-IR研究

利用傅立叶变换红外(FT-IR)和拉曼(FT-Raman)光谱研究了高浓度磷脂酰胆碱(PC)与牛血清白蛋白(BSA)的相互作用,及Eu3＋对该作用的影响.FT-IR结果显示,PC/BSA混合体系中二者的相互作用主要发生在PC头部极性基团,且这一作用随BSA含量的增加而增强,作用后蛋白质二级结构中α螺旋的比例有所增加. FT-Raman光谱说明PC与BSA的相互作用影响磷脂CH链的排列有序程度. PC/BSA/Eu3＋体系的红外光谱显示, Eu3＋与PC的磷氧键发生了强相互作用,并使蛋白α螺旋的比例进一步增加.     

天然和人工培植红景天挥发油的对比研究

应用ＧＣ－ＭＳ和ＧＣ－ＩＲ两种联机法对比研究了天然和人工培植红景天挥发油、分别鉴定出２７个和２４个化合物。ＭＳ给出结构信息和ＩＲ给出官能团信息相结合，提高了分析测试复杂样品的可靠性。     

Na3Fe(C2O4)3·5H2O的热解过程和FAB-MS断裂规律

以红外光谱法为主要手段，原位“跟踪”测定铁（Ⅲ）与乙二酸形成的配合物Ｎａ３Ｆｅ（Ｃ２Ｏ４）３．５Ｈ２Ｏ的热解过程，分析了气、固相热解产物。并以色谱分析、差热－热重分析和Ｘ－射线粉末衍射法定性、定量地验证其结果。测定了该配合物快原子轰击质谱，提出了断裂规律。铁的二元羧酸配合物的质谱尚属首见。     

Spectral and Thermal Studies of Rare Earth Complexes With 2,4,6-trimethylbenzoic Acid

The rare earth element 2,4,6-trimethylbenzoates were prepared as solids with the general formula Ln(C₁₀ H₁₁ O₂ )₃ ×n H₂ O, where n =2 for Ln =Y, La–Nd, and n =1 for Ln =Sm–Lu. The IR spectra of the complexes prepared were recorded and their solubilities in water and thermal decomposition in the air were investigated. During heating the hydrated complexes lose all the crystallization water molecules in one (Y, Ce–Lu) or two steps (La) and then the anhydrous complexes decompose either directly to oxides (Y, Ce, Pr, Sm–Lu) or with intermediate formation oxocarbonates Ln₂ O₂ CO₃ (La, Nd). The carboxylate groups in the complexes prepared act probably as mono- and bidentate. This revised version was published online in July 2006 with corrections to the Cover Date.     

含氯聚合物和乙烯-醋酸乙烯酯共聚物共混体系的红外光谱研究

关于氯化聚乙烯(CPE)或聚氯乙烯(PVC)与乙烯—醋酸乙烯酯共聚物(EVA)共混体系相容性的研究,已有不少报道,其中Coleman等人运用FTIR方法研究了含VA45％的EVA与CPE、PVC的共混体系,测定了该体系的低临界共溶温度(LCST)。一般认为,如果VA含量更低,由于EVA本身的结晶,共混体系将变得难以     

State of Molecules and Ions in the Structural Channels of Synthetic Beryl with an Ammonium Impurity

The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containing solution, were investigated by IR and EPR spectroscopy. Using IR spectroscopy we found that water molecules, ammonium ions, and a small number of HCl molecules enter the structural channels of beryl in the course of mineral growth. In these beryls, the ammonium ions play the role of alkali cations. The ammonium ions are as rigidly fixed in the lattice as are water molecules; they are eliminated by calcination at high temperatures close to the decomposition temperature. On exposure to radiation at 77 K, the paramagnetic NH ₃ ⁺ and H⁰ radicals are stabilized in the structural channels of beryl. In addition to the known H⁰ radical, other states of atomic hydrogen, interacting with medium protons, are observed as well. For one of the additional radicals, H_b, we suggest the model of atomic hydrogen stabilized at the center of a silicon-oxygen ring with two water molecules in adjacent cavities.     

Structure and hydration of polycytidylic acid from the data of infrared spectroscopy, EHF dielectrometry and computer modeling

The aim of this paper is to summarize the original results concerned with the elucidation of the role of water environment in the formation of different structures of polyribocytidylic acid (poly(rC)), depending on the pH, temperature and ion content. To solve this problem, we studied the hydration of poly(rC)-K⁺ in films differing in water content, by methods of infrared spectroscopy and piezogravimetry, and in solution, using the dielectric measurements at a wavelength of 7.6 mm (extremely high frequencies — EHF). The experimental results were confirmed by a Monte Carlo simulation of the interaction between water molecules and single-strand and double-strand poly(rC) fragments in clusters of 800 water molecules. A model of hydration of double-strand complex of poly(rC)⁺-poly(rC) has been proposed based on our results and the known X-ray parameters of the complex. The obtained results and proposed structure of poly(rC)⁺-poly(rC) suggest that, the stabilization of this complex occurs due to intra- and inter-chain water bridges, together with the hydrogen bonds between neutral and protonated cytosines in pairs.