An overview on the development of macromolecule-metal complexes and brief sketch on their recent trends

In early 1970s, there was growing tendency that the macromolecule-metal complexes should have been understood as a molecular science among many international scientists. Y. Y. Jiang, Academia Scinica, firstly proposed an international symposium on this field and the first congress (MMC-1) was held in 1985. From the 4th one, this series has been under the auspices of IUPAC and we have reached MMC-7. The current interests in this field are, for example, photoinduced electron transfer, outer-sphere process, chemical reactions in subnano-geometrical space, multi-electron transfer reaction. They are all linked to the high performances of advanced materials. The role of macromolecules in macromolecule-metal complexes are summarized and recent topics of this area are described.     

Polythiophenylene synthesis through multi-electron transfer process

Superacidification of aromatic sulfoxides effects the electrophilic substitution reaction of the resulting hydroxysulfonium ions onto aromatic rings with the elimination of H₂O at room temperature. The product, the alkyldiarylsulfonium ion, allows the synthesis of alkylsulfonio-bridged (λ⁴-alkylsulfanyliumdiyl) aromatic polymers. High molecular-weight poly(alkylsulfonioarylene) salts have been made accessible by the regioselective condensation of aryl sulfoxides. Polymers having a wide variety of structural dimensionalities such as linear, hyper-branched and ladder-type structures can be prepared by this method, which possess interesting properties such as good solubility in polar organic solvents and sometimes even in H₂O, susceptibility to nucleophiles to provide thioarylene derivatives, photo-degradability, and electric semiconductivity based on a 3d-2p interaction in aryl sulfonium ion.     

Synthesis,magnetic, and optoelectronic properties of poly(triphenylamine‐alt‐phenylenevinylene)s

Conjugated polymers alternatively involving m‐phenylenevinylene or p‐phenylenevinylene and a triphenylamine moiety in the main chain were synthesized via a Wittig–Horner‐type polycondensation of 4‐diformyl‐4′,4″‐dimethyl‐triphenylamine or 4‐diformyl‐4′,4″‐dimethoxy‐triphenylamine with m‐xylene‐bis(diethylphosphonate) or p‐xylene‐bis(diethylphosphonate). A high glass‐transition temperature (ca. 120 °C) and thermal stability (5% weight loss at temperatures greater than 450 °C) were observed for all polymers. These polymers, especially poly(methyltriphenylamine‐alt‐p‐phenylenevinylene), fluoresced a strong green color under UV irradiation, with a quantum efficiency of 50% for their chloroform solutions. Cyclic voltammetry showed a relatively low ionization potential (5.18–5.44 eV) for the polymers. These results suggest that these polymers satisfied the requisites of polymer materials for a single‐layer light‐emitting diode. The aminium radical derived from the oxidation of poly(triphenylamine‐alt‐m‐phenylenevinylene) satisfied both non‐Kekulé‐type π conjugation and ferromagnetic connectivity of the unpaired electrons and displayed a multiplet ground state. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4119–4127, 2000     

Design and Evaluation of Tumor-Specific Dendrimer Epigenetic Therapeutics

Histone deacetylase inhibitors (HDACi) are promising therapeutics for cancer. HDACi alter the epigenetic state of tumors and provide a unique approach to treat cancer. Although studies with HDACi have shown promise in some cancers, variable efficacy and off-target effects have limited their use. To overcome some of the challenges of traditional HDACi, we sought to use a tumor-specific dendrimer scaffold to deliver HDACi directly to cancer cells. Here we report the design and evaluation of tumor-specific dendrimer–HDACi conjugates. The HDACi was conjugated to the dendrimer using an ester linkage through its hydroxamic acid group, inactivating the HDACi until it is released from the dendrimer. Using a cancer cell model, we demonstrate the functionality of the tumor-specific dendrimer–HDACi conjugates. Furthermore, we demonstrate that unlike traditional HDACi, dendrimer–HDACi conjugates do not affect tumor-associated macrophages, a recently recognized mechanism through which drug resistance emerges. We anticipate that this new class of cell-specific epigenetic therapeutics will have tremendous potential in the treatment of cancer.     

Degradable and chemically recyclable epoxy resins containing acetal linkages: Synthesis,properties, and application for carbon fiber‐reinforced plastics

Four sorts of epoxy resins containing degradable acetal linkages were synthesized by the reaction of bisphenol A (BA) or cresol novolak (CN) resin with vinyl ethers containing a glycidyl group [4‐vinlyoxybutyl glycidyl ether (VBGE) and cyclohexane dimethanol vinyl glycidyl ether (CHDMVG)] and cured with known typical amine‐curing agents. The thermal and mechanical properties of the cured resins were investigated. Among the four cured epoxy resins, the CN‐CHDMVG resin (derived from CN and CHDMVE) exhibited relatively high glass transition temperature (T_g = ca. 110 °C). The treatment of these cured epoxy resins with aqueous HCl in tetrahydrofuran (THF) at room temperature for 12 h generated BA and CN as degradation main products in high yield. Carbon fiber‐reinforced plastics (CFRPs) were prepared by heating the laminated prepreg sheets with BA‐CHDMVG (derived from BA and CHDMVE) and CN‐CHDMVG, in which strands of carbon fibers are impregnated with the epoxy resins containing conventional curing agents and curing accelerators. The obtained CFRPs showed good appearance and underwent smooth breakdown with the aqueous acid treatment in THF at room temperature for 24 h to produce strands of carbon fiber without damaging their surface conditions and tensile strength. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

First total synthesis and absolute stereochemical assignment of vittarilide-A,an antioxidant extractive component isolated from Vittaria anguste-elongata Hayata

The first stereocontrolled synthesis of vittarilide-A and its C5-epimer was completed from d-glucuronolactone. Comparison with the spectroscopic properties reported for authentic material has given a clear indication as to the absolute stereochemistry of the natural vittarilide-A.     

Dissipative crystallization of poly-d-lysine hydrobromide, poly-l-lysine hydrobromide, and their low-molecular-weight analogs

Drying dissipative structures of aqueous solutions of poly-d-lysine hydrobromide, poly-l-lysine hydrobromide, and their low-molecular-weight analogs were studied on a cover glass, a watch glass, and a Petri glass dish. Size of the broad rings, one of the typical macroscopic patterns, decreased as the solute concentration decreased. Microscopic drying crystal patterns of polylysine hydrobromides and their low-molecular-weight analogs, i.e., d-, l-, and dl-lysine hydrochloride changed as a function of the distance from the film center, which is one of the typical features of dissipative crystallization. Macroscopic and microscopic drying patterns were quite similar to each other irrespective of their stereospecificity. The crystal patterns of the mixtures of poly-d-lysine hydrobromide and poly-l-lysine hydrobromide were also similar to those of the corresponding single-component polymers. The stereospecific effects were not observed in this work.     

Heat transfer and flow around a circular cylinder with tripping-wires

An experimental study was conducted on the heat transfer under the condition of constant heat flux and the flow around a circular cylinder with tripping-wires, which were affixed at ± 65° from the forward stagnation point on the cylinder surface. The testing fluid was air and the Reynolds number Red, based on the cylinder diameter, ranged from 1.2 × 10⁴ to 5.2×10⁴. Especially investigated are the interactions between the heat transfer and the flow in the critical flow state, in relation to the static pressure distribution along the cylinder surface and the mean and turbulent fluctuating velocities in the wake. It is found that the heat transfer from the cylinder to the cross flow is in very close connection with the width of near wake.     

A note on an improvement of heat transfer of tube banks

An experimental investigation has been conducted for exploring a possibility to improve the heat transfer of tube banks of in-line arrangement, in which the first cylinder was roughened with pyramids. Measured were the heat transfer characteristics of the first cylinder for several cylinder spacings. It is found that there exists the critical Reynolds numberRe _c , beyond which the heat transfer rate increases drastically by about 30 to 50% as compared with that for the smooth cylinder, though the increasing rate is small for the case of very narrow spacing such asC _y /d×C _x /d =1.2×1.2. In the region ofRe>Re _c , the separation point shifts downstream to θ=120° to 130° from the forward stagnation point, and it results in the decrease of the form drag.