Two 2D Metal‐organic Networks Based on a Rigid Imidazolate/Sulfonate Functionalized Ligand – Effect of the Coordination Modes of the Ligand on Crystal Structures

A rigid imidazolate/sulfonate functionalized ligand, 6‐(4‐sulfonatopheny)imidazo[4, 5‐f]isoindole‐5, 7‐dione (SPID) was designed and used for assembling reactions with Mn²⁺ and Cu²⁺ ions. Two 2D frameworks compounds, [Mn(H_‐1SPID)₂(DMAC)₂] ( 1 ) and [Cu(H_‐2SPID)(H₂O)₂] · 0.7DMAC · 0.3H₂O ( 2 ) (DMAC = N,N‐dimethylacetamide) were obtained. Single crystal X‐ray analyses show that 1 has a 2D (4, 4)‐net based on 4‐connected Mn²⁺ nodes and μ₂‐coordinated H_‐1SPID spacers, whereas compound 2 has a 2D (6, 3)‐net built of 3‐connected Cu²⁺ nodes and μ₃‐coordinated H_‐2SPID spacers. Additionally, the thermal behavior of 1 and 2 is presented.     

Improved list coloring algorithm in cognitive radio based on time cost and demand satisfaction

For the cognitive users to access the licensed frequency bands opportunistically, cognitive radio is the best solution to mitigate the spectrum resource scarcity at the moment. Dynamic spectrum allocation is a key technology to implement cognitive radio efficiently on the condition that the licensed users must not be interfered. Up to now, the spectrum allocation algorithms based on the graph model seldom focus on enhancing spectrum utilization, speedy accomplishing and requirement satisfaction simultaneously. In this paper, an improved algorithm is proposed to decrease time cost and increase demand satisfaction simultaneously based on a List-Coloring algorithm provided by Wei Wang research group. This improved algorithm was studied by handling connected component in parallel and depressing user’s priority which demand has been met, respectively. And the spectrum utilization is effectively guaranteed at the same time. Our experimental results show that the proposed algorithm is an efficient method. Compared with the original List-Coloring algorithm, the time cost is reduced obviously and the demand satisfaction is greatly improved while only a few bandwidth rewards are lost by using the algorithm proposed in our study.     

Dicarboxylic acid promoted immortal copolymerization for controllable synthesis of low‐molecular weight oligo(carbonate‐ether) diols with tunable carbonate unit content

Low‐molecular weight oligo(carbonate‐ether) diols are important raw materials for polyurethane formation, which with tunable carbonate unit content (CU) may endow new thermal and mechanical performances to polyurethane. Herein, facile synthesis of oligo(carbonate‐ether) diols with number average molecular weight (M_n) below 2000 g mol^?1 and CU tunable between 40% and 75% are realized in high activity by immortal copolymerization of CO₂/propylene oxide (PO) using zinc‐cobalt double metal cyanide complex (Zn‐Co‐DMCC) in the presence of sebacic acid (SA). M_n of the oligomer is in good linear relationship to the mole ratio of PO and SA (PO/SA) and hence can be precisely controlled by adjusting PO/SA. Besides, the molecular weight distribution is quite narrow due to the rapid reversible chain transfer in the immortal copolymerization. High pressure and low temperature are favorable for raising CU. In all the reactions, the weight fraction of propylene carbonate (W_PC) can even be controlled as low as 2.0 wt %, and the catalytic activity of Zn‐Co‐DMCC is above 1.0 kgg^?1 cat. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Dioxygen affinities of Schiff base cobalt(II) complexes with aza-crown or morpholino pendants

Abstract  

Schiff base Co(II) complexes, CoL₂¹–CoL₂⁶ with aza-crown or morpholino pendants were synthesized. The oxygenation constants (KO₂) of these complexes in MeOCH₂CH₂OMe solution were measured over the range of −5 to 25 °C, and the thermodynamic parameters (∆H ⁰, ∆S ⁰) for oxygenation were calculated based on these KO₂ values. The effects of different substituents on the Schiff base ligand with respect to the modulation of O₂-binding capability were explored. The results indicate that the dioxygen affinities of the Co(II) complexes are much more enhanced by aza-crown pendants than that by morpholino pendants, and the O₂-binding capabilities of the aza-crown pendants complexes can also be enhanced by adding Na⁺ cations.     

Synthesis and solvent‐dependent micellization of the amphiphilic block copolymer poly(styreneboronic acid)‐block‐polystyrene

The amphiphilic organoboron block copolymer poly (styreneboronic acid)‐block‐polystyrene ( PSBA‐b‐PS ) has been prepared through a postpolymerization modification route from the silicon‐functionalized block copolymer poly(4‐trimethylsilylstyrene)‐block‐polystyrene ( PSSi‐b‐PS ). PSBA‐b‐PS is obtained through highly selective reaction of PSSi‐b‐PS with BBr₃ at room temperature and subsequent hydrolysis of the BBr₂‐functionalized intermediate. Transmission electron microscopy studies demonstrate that PSBA‐b‐PS undergoes pH dependent micellization in aqueous solution. Different morphologies could be realized by using different mixtures of water and organic solvents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2438–2445, 2010     

新媒体融合播控系统研究与架构设计

本文研究并设计了一种新型的新媒体融合播控系统平台,既实现了IPTV和OTT内容的统一管理,又为多网络、多终端提供相应的适配,以适应多渠道的内容运营、发布、传播与接收。     

Palladium‐Initiated Radical Cascade Stereoselective Iodofluoroalkylation/Cycloisomerization of Ene‐vinylidenecyclopropanes

A novel and convenient palladium‐initiated radical cascade stereoselective iodofluoroalkylation/cycloisomerization of ene‐vinylidenecyclopropanes with fluoroalkyl iodides has been developed. The reaction proceeds under mild reaction conditions with high atom economy and stereoselectivity, thereby allowing an efficient access to a variety of difluoromethylated or perfluoroalkylated pyrrolidines tethered with an alkyl iodide. Two plausible radical pathways for the transformation have been proposed on the basis of the results of control experiments and previous reports, which in one case it was thought that palladium(0) was an initiator rather than a catalyst.