Initiation process of L‐lactide polymerization carried out with zirconium(IV) acetylacetonate

Lactide polymerization using zirconium(IV) acetylacetonate [Zr(acac)₄] as an initiator was investigated. In the reaction between Zr(acac)₄ and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution NMR spectroscopy. A computational method was used to calculate the hypothetical structures. The role of the obtained complexes in the initiation of polymerization and the reaction of chain growth was proposed. The influence of the reaction temperature on the structures of the complexes was investigated. Polylactide chain growth proceeded by an insertion‐coordination mechanism. The polymer chain grew on one ligand, which was formed in advance from a deprotonated lactide. The molecular masses of the obtained polymers were the same as the theoretical masses and were directly proportional to the reaction conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1886–1900, 2004     

Construction of nonanuclear supramolecular structures from simple modular units

A porphyrazine based supramolecule with a nonanuclear structure has been prepared by the ready coordination of pyridine donor sites in octakis(4-pyridoxyethylthio)porphyrazinatomagnesium with vanadyl bis(acetylacetonate) and characterized by EPR spectroscopy.     

Thermal properties of sodium acetylacetonate

Sodium acetylacetonate was prepared by the interaction of acetyl acetone with sodium hydroxide. The thermal conductivity, phonon velocity, mean free path, Yong's modulus, and the thermal expansion coefficient were studied. The thermal conductivity of the material decreases with increasing temperature due to the thermal lattice scattering of phonons. The velocity of phonons is also decreased due to the perturbation of thermal phonons. The linear thermal expansion coefficient increases with temperature due to the weakness of the attractive forces between the small Na⁺ cations and bulkier acetylacetonate anions in the lattice.

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Zusammenfassung Natriumacetylacetonat wurde durch die Wechselwirkung zwischen Acetylaceton und Natriumhydroxid gewonnen. Es wurde die Wärmeleitfähigkeit, die Phononengeschwindigkeit, die mittlere freie Wegstrecke, das Elastizitätsmodul und der Wärmeausdehnungskoeffizient untersucht. Die Wärmeleitfähigkeit der Substanz nimmt wegen der thermischen Gitterstreuung der Phononen mit steigender Temparatur ab. Die Geschwindigkeit der Phononen nimmt auf Grund der Perturbierung der thermischen Phononen ebenfalls ab. Der lineare Wärmeausdehnungskoeffizient steigt mit zunehmender Temperatur an, was auf die schwachen Anziehungskräfte zwischen den kleinen Na⁺ Ionen und den massigen Acetylacetonat-Anionen im Gitter zurückzuführen ist.

     

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅧ. THE POLYMERIZATION KINETICS OF BENZONITRILE CATALYZED BY METAL ACETYLACETONATE

The bulk polymerization of benzonitrile catalyzed by Co(Ⅱ), Co(Ⅲ) and Fe(Ⅲ) acetylacetonate was studied. The results of kinetics study show that the rate of polymerization was proportional to first power of the concentration of catalyst and second power of the concentration of monomer.     

Barbier coupling in water: SnCl2-mediated and Co(acac)2-catalyzed allylation of carbonyls

Co(acac)₂·2H₂O efficiently catalyzes SnCl₂-mediated Barbier coupling in water between carbonyls, including aromatic, aliphatic and α,β-unsaturated aldehydes, ketones, sugars and allyl bromide to afford the corresponding homoallylic alcohols in high yields. The catalyst was reused for several cycles with consistent activity.     

乙酰丙酮钇催化环氧氯丙烷的均聚合与共聚合

用过渡金属络合催化剂聚合环氧氯丙烷能获高分子量的聚合物。稀土络合催化剂对环氧乙烷,环氧丙烷及环硫丙烷的开环聚合具有明显效果。本文选用Y(acac)_3-H_2O-Al(i-Bu)_3催化剂,考察环氧氯丙烷的均聚合及其与环氧乙烷,环氧丙烷的共聚合,并用核     

Preparation of γ-Fe2O3/SiO2-capsule composites capable of using as drug delivery and magnetic targeting system from hydrophobic iron acetylacetonate and hydrophilic SiO2-capsule

Series of nanocomposites with γ-Fe₂O₃ supported on SiO₂-capsules were prepared by adsorption of hydrophobic iron acetylacetonate on the hydrophilic surface of SiO₂-capsules in the evaporation process of the solvent and then calcination the complex at 450 °C. The adsorption and calcination conditions were studied and the resultant nanaoparticles were characterized by XRD, XRF and TEM in detail. The results indicated that γ-Fe₂O₃ loaded discontinuously but uniformly on the surface of SiO₂-capsules at appropriate content. The specific surface area characterization and doxorubicin hydrochloride release shown although the surface area of the target composites decreased slightly, the nanoparticles still had large potential using as drug delivery and magnetic targeting system.     

乙酰丙酮氧钼催化的苯乙烯双羟化反应

以钼酸铵与乙酰丙酮反应生成催化剂乙酰丙酮氧钼MoO2(acac)2,考察了反应溶剂、氧化剂存在形式、不同助催化剂、反应温度、底物配比和催化剂量对苯乙烯双羟化反应的影响。在优化的反应条件下,以过氧叔丁醇为氧化剂得到苯乙烯双羟化反应的转化率、化学选择性和分离产率分别为85.2%、70.7%和53.3%。并探讨了可能的催化机理以及改进方向。     

Epoxidation of styrene catalyzed by metal complexes of poly(vinylbenzyl)acetylacetonate

The epoxidation of styrene to styrene oxide at higher than 96% yield has been achieved by the catalysis by poly-(vinylbenzyl)acetylacetonate complexes of cobalt(II) or manganese(II) in the presence of isobutyraldehyde under an atmospheric pressure of molecular oxygen at room temperature. The kind of aldehyde and aldehyde/styrene molar ratio greatly influenced the reaction. The catalyst could be recycled, but after recycling for five times, the yield of styrene oxide decreased from 96.0% to 84.6%.     

铱-芴主链型共聚物的合成与光致发光性能

合成以2-(4-溴苯基)苯并咪唑为环金属配体、乙酰丙酮为辅助配体的铱配合物客体单元,并通过Suzuki缩聚方法将客体引入聚芴(PFO)主体中,合成了主链型共聚物。通过元素分析、红外光谱、1 H-NMR等分析手段对产物进行了结构表征,通过紫外吸收光谱、稳态和瞬态荧光光谱对铱配合物、共聚物的光物理性能进行了研究。结果表明:铱配合物最大发射峰位于505nm和535nm,为绿光发射;共聚物同时呈现蓝光主体PFO和绿光客体铱配合物的发射,且随铱配合物含量提高,绿光强度明显增强,显示了主客体能量的部分转移,通过调节共聚物中铱配合物单元的含量,使共聚物的发光颜色从蓝光向绿光转移;当铱配合物的物质的量分数为2%时,蓝色荧光强度大于绿色磷光,共聚物色坐标刚好处于蓝绿交界处,当铱配合物物质的量分数大于2%时,共聚物呈现绿色发光;与铱配合物的荧光量子效率(2.7%)相比,共聚物的荧光量子效率均有显著增加;共聚物热稳定性良好。