Highly Enantioselective Catalytic System for Asymmetric Copolymerization of Carbon Dioxide and Cyclohexene Oxide

A new ligand can be easily prepared, and its intramolecular dinuclear zinc complexes act as a high performance catalyst for the asymmetric alternating copolymerization of cyclohexene oxide and CO₂ under very mild conditions (1 atm CO₂, room temperature), affording completely alternating polycarbonates with up to 93.8 % enantiomeric excess (ee) and 98 % yield. A high M_n value of 28 600 and a relatively narrow polydispersity (M_w/M_n ratio) of 1.43 were also achieved.     

Solvothermal Transformation of a Calcium Oleate Precursor into Large‐Sized Highly Ordered Arrays of Ultralong Hydroxyapatite Microtubes

Hydroxyapatite (HAP), a well‐known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three‐dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core–shell‐structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications.     

Highly Flexible and Nonflammable Inorganic Hydroxyapatite Paper

A highly flexible and nonflammable inorganic hydroxyapatite (HAP) paper made from HAP ultralong nanowires is reported. The paper can be used for printing and writing and is promising for the permanent and safe storage of information, such as archives and important documents. The HAP paper is also an excellent and recyclable adsorbent for organic pollutants.     

Coloring properties of novel 1,4-distyrylbenzene and 4,4′-distyrylbiphenyl fluorescent brighteners and their arrangement in cotton and polyester fiber

Some novel 1,4-distyrylbenzene (DSB) and 4,4′-distyrylbiphenyl (DSBP) fluorescent brighteners (FBs) were used to dye polyester and cotton fabrics. The CIE whiteness, color hue and reflectance spectrum of dyed fabrics were compared. DSBP derivatives could dye the cotton and polyester fabrics with a higher whiteness level and had a lower fluorescent quenching concentration than DSB derivatives. The color hue for the fabric dyed with DSB FBs was yellow-green, whereas that dyed with DSBP was blue–violet. The molecular arrangement in the fiber had a significant influence on their optical properties, resulting in different coloring properties. The increase in molecule planarity and rigidity generated by the interaction between the polymer and FB molecules caused a remarkable bathochromic shift in emission and excitation spectra. The H-aggregate of the DSB molecule in the fiber was easily generated, and the degree of aggregation increased with the molecular polarity. However, the aggregation of DSBP molecules in the polyester and cotton fiber was not found. The surface region of the cotton fiber was filled with FB molecules, whereas FB molecules in the polyester fiber aggregated easily, and incident light could pass through the surface region.     

Effects of lignin and hemicellulose contents on dissolution of wood pulp in aqueous NaOH/urea solution

Four species of delignified woodchips with about 1 % lignin content (Chlorite–Woodchips) and a series of softwood pulps with different lignin contents were prepared by sodium chlorite delignification. After mechanical defibration, some Chlorite–Woodchips were directly subjected to dissolution treatment in NaOH/urea solvent; the others were first treated with NaOH solution to remove the hemicellulose to obtain NaOH–Chlorite–Woodchips or oxidized with potassium permanganate (OPP) to remove lignin completely to obtain OPP–Chlorite–Woodchips, and then subjected to the dissolution in NaOH/urea solvent. The results showed that the dissolved proportion of the Chlorite–Woodchips ranged from 36 to 46 %, the dissolved proportion of glucan was within 12 %, and most of the hemicellulose was dissolved in NaOH/urea solvent. Compared with Chlorite–Woodchips, the dissolved proportion of NaOH–Chlorite–Woodchips was lower, but their dissolved proportion of glucan was higher. After further permanganate delignification, both the dissolved proportion of the OPP–Chlorite–Woodchips and the dissolved proportion of glucan of the OPP–Chlorite–Woodchips were higher than those of the Chlorite–Woodchips. However, the dissolved proportion of glucan was still limited to only 15–30 %. The effect of the lignin content of softwood pulps on their dissolution is complicated. With the decrease of the lignin content of softwood pulp from 6.9 to 2.8 %, the dissolved proportion of pulp increased from 14 to 26 %. However, further reduction of lignin content from 2.8 to 0.3 % led to a decrease in the dissolved proportion of pulp from 26 to 12 %. The dissolved proportion of glucan followed the same tendency. These results indicated that the dissolution of wood cellulose in NaOH/urea solvent is not simply controlled by the hemicellulose and lignin contents, but also by some other factors.     

新型环状聚(ε-己内酯-co-γ-三乙基硅氧基-ε-己内酯)的合成

设计合成了具有精确分子结构的聚合物对深入了解其结构与性能之间的关系起着至关重要的作用。研究了一种合成带有三乙基硅氧侧基的环状无规共聚酯的新方法。功能性单体γ-三乙基硅氧基-ε-己内酯(γ-Et3SiOεCL)和ε-己内酯(ε-CL)在环状引发剂2,2-二丁基-2-锡-1,3-二氧环庚烷(DSDOP)的作用下,进行活性开环聚合反应以制备活性环状无规共聚酯(LCP(εCLcoγEt3SiOεCL))前体,当单体完全转化后,以该活性环状前体作为大分子引发剂,引发反应性单体α-(1-丙烯酰氧乙基)-ε-己内酯(αAEεCL)进行嵌段聚合反应,合成了在活性中心附近带有不饱和双键的功能性环状嵌段共聚酯,即活性环状聚(ε-己内酯-co-γ-三乙基硅氧基-ε-己内酯)-b-(α-(1-丙烯酰氧乙基)-ε-己内酯)。最后该活性环状嵌段共聚酯在紫外光照射下,反应性单体结构单元中的双键发生分子内交联反应,从而制得稳定的不含有机锡的新型环状无规共聚酯cP(εCLcoγEt3SiOεCL)(Mn,NMR=28500)。采用SEC、1H NMR以及DSC等技术手段对聚合物的结构和性能进行表征。该方法的突出特点是能够高效地合成带有功能性侧基的高相对分子质量的环状无规共聚酯。     

(P^N^P)钴配合物/倍半氯化乙基铝催化苯乙烯聚合的研究

采用含氮双膦配体与无水氯化钴反应可制得一系列相应的(P^N^P)钴配合物,并研究了该系列钴配合物对苯乙烯聚合的催化性能.在助催化剂倍半氯化乙基铝(EASC)的活化下,该系列钴配合物对甲苯中的苯乙烯溶液聚合表现出高的催化活性(可达5.44×105g(PS)·mol-1(Co)·h-1).通过对不同苯乙烯单体用量、助催化剂用量(Al/Co摩尔比)、聚合温度以及催化剂的配体环境等的研究,详细考察了这些因素对聚合反应和聚合产物性能的影响.通过凝胶渗透色谱法(GPC)和核磁共振碳谱(13C-NMR)表征了所得聚合产物的分子量及分子量分布和微观结构,分析结果表明,所得聚苯乙烯具有较低的分子量(Mn=2000~5900)和较窄的分子量分布(1.75~2.05),其微观结构是无规的.     

Lithiation of a Silyl Ether: Formation of an ortho‐Fries Hydroxyketone

A hydroxy‐directed alkylation of an N,N‐diethylarylamide using CIPE‐assisted α‐silyl carbanions (CIPE=complex‐induced proximity effect) has been developed using a simple reagent combination of LDA (lithium diisopropylamide) and chlorosilane. A study of the mechanism, and the application of the procedure to an anionic Snieckus–Fries rearrangement for a highly efficient synthesis of the potent phosphatidylinositol 3‐kinase (PI3K) inhibitor LY294002, are reported.     

CO/C‐H as an Acylating Reagent: A Palladium‐Catalyzed Aerobic Oxidative Carbonylative Esterification of Alcohols

A palladium‐catalyzed oxidative carbonylative esterification of a variety of functionalized alcohols under base‐ and ligand‐free conditions has been demonstrated. A CO/olefin combination was utilized as the acylating reagent with O₂ as a benign oxidant. Notably, the scope of the substrate alcohols has been greatly broadened.     

Conjugated‐Polyelectrolyte‐Based Polyprodrug: Targeted and Image‐Guided Photodynamic and Chemotherapy with On‐Demand Drug Release upon Irradiation with a Single Light Source

Nanomaterials that combine diagnostic and therapeutic functions within a single nanoplatform are highly desirable for molecular medicine. Herein we report a novel theranostic platform based on a conjugated‐polyelectrolyte (CPE) polyprodrug that contains functionality for image, chemo‐ and photodynamic therapy (PDT), and on‐demand drug release upon irradiation with a single light source. Specifically, the PEGylated CPE serves as a photosensitizer and a carrier, and is covalently conjugated to doxorubicin through a linker that can be cleaved by reactive oxygen species (ROS). Under appropriate light irradiation, the CPE can generate ROS, not only for PDT, but also for on‐demand drug release and chemotherapy. This nanoplatform will offer on‐demand PDT and chemotherapy with drug release triggered by one light switch, which has great potential in cancer treatment.