'Living' controlled in situ gelling systems: thiol-disulfide exchange method toward tailor-made biodegradable hydrogels

A 'living' controlled hydrogel formation method was first reported to create loose and compact in situ biodegradable hydrogels. The method executed under mild reaction conditions can conveniently tailor the hydrogel properties, and it has the potential to develop into a powerful tool for the design, synthesis, and self-assembly of novel tailor-made biomaterials and drug delivery systems.     

Mediated Electron Transfer Across Supported Bilayer Lipid Membrane with TCNQ‐Based Organometallic Compounds

Supported bilayer lipid membrane (s‐BLM) containing one‐dimensional compound 1, TCNQ‐based (TCNQ=7,7,8,8‐tetracyanoquinodimethane) organometallic compound {(Cu₂(μ‐Cl)(μ‐dppm)₂)(μ₂‐TCNQ)}_∞, was prepared and characterized on the self‐assembled monolayer (SAM) of 1‐octadecylmercaptan (C₁₈H₃₇SH) deposited onto Au electrode. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the compound 1, dotted inside s‐BLM, can act as mediator for electron transfer across the membrane. Two redox peaks and the charge‐transfer resistance of 400 kΩ were observed for compound 1 inside s‐BLM. The mechanism of the electron transfer across s‐BLM by TCNQ is by electron hopping while TCNQ‐based organometallic compound is by conducting. Further conclusion drawn from this finding is that the TCNQ‐based organometallic compound embedded inside s‐BLM exhibits excellent electron transfer ability than that of free TCNQ. This opens a new path for the development of s‐BLM sensor and/or biosensor by incorporation with TCNQ‐based organometallic compounds.     

Triphenylamine and quinoline-containing polyfluorene for blue light-emitting diodes

A novel blue light-emitting polyfluorene-based copolymer PTHD containing electron-rich triphenylamine and electron-poor phenylquinoline side chains in the C-9 position of fluorene unit is described. By comparison of the solution and thin film photoluminescence (PL) spectra of PTHD, a considerable red-shift of Δλ = 10-15 nm was observed in the thin film PL spectrum. The emission intensity of the shoulder peak appeared in dilute solution was also significantly enhanced in the thin film. In contrast to the reference polymer poly{[9,9-dihexylfluorene]-alt-[9,9-di(2,4-diphenylquinoline)fluorene]}, PTHD exhibits higher HOMO energy level, and higher maximum brightness with the PLED device configuration of ITO/PEDOT:PSS/polymer_70% + PBD_30%/TPBI/LiF/Al.     

Effect of Zn on the adsorption of CO on Pd(111)

Introduction of a second metal can greatly modify the surface reactivity of a host metal. Recently Jeroro and Vohs found that Pd(111) deposited with 0.03-0.06 monolayer of Zn might possess unique activity to methanol steam reforming reaction. To investigate the distribution of the deposited Zn, we examined the adsorption of CO on two types of model systems. In the first model, Zn is in the top-layer of Pd(111) only, while in the second model Zn is placed in the subsurface exclusively. It is found that Zn atoms in the topmost layer show negligible effect on CO adsorption especially at hollow sites, whereas the second layer Zn atoms affect significantly the interaction of CO with the substrate. It is revealed that the negligible influence of the first layer Zn on CO adsorption is due to the offsetting of the ligand effect by the strain effect. On the other hand, the ligand effect dominates the CO adsorption in the second model where the strain effect is insignificant. It is demonstrated that the d-band centers correlate well with the binding energies of the second model, whereas no such good correlation exists for the first model. Our results show that the subsurface plays a more important role and the observed dramatic modification of surface reactivity of Pd(111) deposited with 0.03-0.06 ML Zn is most likely originated from the subsurface Zn atoms, if the coverage is not underestimated and the deposited Zn atoms are distributed uniformly within a layer.     

Syntheses and Structural Characterization of 1D Chain and 1D Ladder Coordination Polymers Assembled from Exo‐bidentate Imidazolyl Ligands

Five novel coordination polymers, [(Cu(L¹)₂OH) · Cl · 3H₂O] ( 1 ) [L¹ = bis(N‐imidazolyl)methane], [Cd(L¹)₂(NCS)₂] ( 2 ), [Zn(L¹)₂(NCS)₂] ( 3 ), [Cu(L¹)₂(NO₃)₂] ( 4 ), and [Cu(L²)_1.5(NCS)₂] ( 5 ) [L² = 1,4‐bis(N‐imidazolyl)butane] were obtained from self‐assembly of the corresponding metal salts with flexible ligands and their structures were fully characterized by X‐ray diffraction (XRD) analysis, Fourier Transform Infrared (FT‐IR) spectroscopy, elemental analysis and thermogravimetric (TGA) measurements. X‐ray diffraction analyses revealed that complexes 1 , 2 , 3 , and 4 exhibit 1D double‐stranded chain structures, which result from doubly bridged [CuOH], [M(NCS)₂] (M = Cd, Zn), and [Cu(NO₃)₂] units, respectively. The polymeric copper complex 5 displays 1D ladder structure., These complexes, with the exception of complex 1 , are stable up to 300 °C.     

Thermal lens spectrometry for the synthesis and study of nanocomposites on the basis of silver salts absorbed by a polyacrylate matrix

Thermal lens spectrometry is applied to determine the absorption of transparent nanocomposite materials, which are produced by the thermal decomposition of silver salts absorbed in the bulk of a polymethacrylate matrix. The high spatial resolution of determination, corresponding to the size of laser beams, makes it possible to evaluate the homogeneity for the distribution of coloration in the matrix. The advantages of thermal lens spectrometry over spectrophotometry include the weak effect of sample scattering on the results of its absorption determination and a higher sensitivity of determination, which may exceed that of spectrophotometry by one or two orders of magnitude. The possibility of achieving local syntheses of nanosized particles in the bulk of the matrix by virtue of the photoinduced decomposition of silver salts in initial polyacrylate materials is shown. Thermal lens experiments also allow the combination of the synthesis of silver nanoparticles and control of the absorbance for the prepared structural units.     

Hydroxyl Radicals Formation in Dielectric Barrier Discharge During Decomposition of Toluene

A method based on high performance liquid chromatography (HPLC), has been developed to measure hydroxyl radical (^·OH) in plasma reactors. The determination was performed indirectly by detecting the products of the reaction of ^·OH with salicylic acid (SAL). The applicability, and effect of time, specific input energy (SIE), relative humidity (RH), catalyst were investigated. It was found that 3 h was the optimal trapping time; concentration of ^·OH was (5.9–23.6) × 10¹³ radicals/cm³ at SIE range. The highest ^·OH yield and toluene removal efficiency (η) were achieved with a RH of 20%. With MnO _x , η was two times that without catalyst, while ^·OH yield in gas stream was one-sixth that without catalyst. However, if summed with ^·OH adsorbed on catalyst surface, the total ^·OH yield was the same as without catalyst. Experiments performed with/without toluene allowed to determine the role of ^·OH on decomposition of toluene in air plasma.     

Microwave-assisted and conventional synthesis and stereogenic properties of monospirocyclotriphosphazene derivatives

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with N/O donor type N-alkyl or (aryl)-o-hydroxybenzylamines HO(C₆H₄)CH₂NHR(Ar), [R(Ar) = C(CH₃)₃ (1), Ph (2)] produce monospirocyclic tetrachlorocyclotriphosphazenes (1a and 2a). The geminal substituted cyclotriphosphazenes (1b, 1d, 2b and 2d) are obtained from the reactions of 1 equiv. of 1a and 2a with 2 equiv. of pyrrolidine or morpholine in THF, while the fully substituted phosphazenes (1c, 1e, 2c and 2e) are formed from the reactions of 1a and 2a with the excess pyrrolidine or morpholine in toluene, between 24 and 48 h. The microwave-assisted reactions of 1a and 2a with excess pyrrolidine or morpholine in toluene afford the fully substituted products with higher yields than those which were obtained by conventional methods. The structural investigations of the compounds have been verified by elemental analyses, ESI-MS, FTIR, ¹H, ¹³C, ³¹P NMR and HETCOR techniques. The crystal structure of 2a is determined by X-ray crystallography and the phosphazene ring is in the flattened boat form. Compounds 1b, 1d, 2b and 2d in which the spiro aryloxy moiety provides the one centre of chirality exist as racemates and the chirality has been confirmed by ³¹P NMR spectroscopy on addition of a chiral solvating agent (CSA), (S)-(+)-2,2,2-trifluoro-1-(9′-anthryl)ethanol.     

Oxygen reduction activity dependence on the mesoporous structure of imprinted carbon supports

Two mesoporous carbons (with 15 (CIC-15) and 26 nm (CIC-26) diameter pores) were synthesized using a silica colloid imprinting method, loaded with 10 wt.% Pt, and then evaluated (against Vulcan^? carbon (VC)) as oxygen reduction (ORR) catalysts for use in proton exchange membrane fuel cells. Both Pt/CICs reproducibly out-performed Pt/VC, with Pt/CIC-15 demonstrating higher ORR activity than Pt/CIC-26, despite its smaller pore size and lower surface area. Transmission electron tomography showed that the Pt nanoparticles (4–5 nm diameter) are fully deposited throughout the pores of the CICs and that the pore distribution in CIC-26 is partially ordered, while CIC-15 shows no ordering of its pores. Importantly, using the powerful imaging capabilities of transmission electron tomography, a first-time correlation is demonstrated between the ORR activity and the wall thickness of the carbon support materials. Pt/CIC-15 has significantly thicker walls, giving a lower measured electronic resistance, a lower ORR Tafel slope, and thus better performance overall compared to Pt/CIC-26.     

Fractionation of phosphopeptides on strong anion‐exchange capillary trap column for large‐scale phosphoproteome analysis of microgram samples

It is one of the key issues to develop powerful fractionating method to increase the identification of the low‐abundance phosphopeptides. In this study, a semi‐online 2‐D LC separation strategy based on three‐step fractionation of the enriched peptides on strong anion‐exchange trap column was developed. It was demonstrated that the sensitivity and phosphoproteome coverage obtained by this fractionating method with strong anion‐exchange trap column is much higher than those by the conventional methods based on C18 trap column. In addition, when the same amount of sample was loaded, the number of identified phosphopeptides had increased 108%. Combination of this three‐step fractionation method with RPLC‐MS/MS analysis by 300 min RP‐gradient separation was applied to phosphoproteome analysis of human liver proteins, and 853 unique phosphopeptides was positively identified from 500 μg tryptic digest of human liver proteins. After three cycles' consecutive analyses, 1554 unique phosphopeptides and 1566 phosphorylated sites were totally identified from 735 phosphorylated proteins at a false discovery rate of <1% in about 54 h of analysis time.