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131.
Dr. Saravanan Gowrisankar Dr. Helfried Neumann Dirk Gördes Kerstin Thurow Dr. Haijun Jiao Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(47):15979-15984
An efficient procedure for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with molecular oxygen under ambient conditions has been achieved. By applying catalytic amounts of Pd(OAc)2 in the presence of tertiary phosphine oxides (O?PR3) as ligands, a variety of substrates are selectively oxidized without formation of ester byproducts. Spectroscopic investigations and DFT calculations suggest stabilization of the active palladium(II) catalyst by phosphine oxide ligands. 相似文献
132.
Erhan Bat Theo G. van Kooten Martin C. Harmsen Josée A. Plantinga Marja J. A. van Luyn Jan Feijen Dirk W. Grijpma 《Macromolecular bioscience》2013,13(5):573-583
Form‐stable resorbable networks are prepared by gamma irradiating trimethylene carbonate (TMC)‐ and ε‐caprolactone (CL)‐based (co)polymer films. To evaluate their suitability for biomedical applications, their physical properties and erosion behavior are investigated. Homopolymer and copolymer networks that are amorphous at room temperature are flexible and rubbery with elastic moduli ranging from 1.8 ± 0.3 to 5.2 ± 0.4 MPa and permanent set values as low as 0.9% strain. The elastic moduli of the semicrystalline networks are higher and range from 61 ± 3 to 484 ± 34 MPa. The erosion behavior of (co)polymer networks is investigated in vitro using macrophage cultures, and in vivo by subcutaneous implantation in rats. In macrophage cultures, as well as upon implantation, a surface erosion process is observed for the amorphous (co)polymer networks, while an abrupt decrease in the rate and a change in the nature of the erosion process are observed with increasing crystallinity. These resorbable and form‐stable networks with tuneable properties may find application in a broad range of biomedical applications.
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A modified glassy carbon (GC) electrode was developed for the amperometric detection of biogenic amines, particularly histamine. The electrode was modified with the co‐enzyme pyrroloquinoline quinone (PQQ) by entrapment during electropolymerziation of pyrrole to form polypyrrole (PPy). This method formed a thin film on the electrode surface possessing very good stability with a shelf‐life exceeding one month without loss of signal. Optimal conditions for the PQQ/PPy electrode were determined and a linear response was found for histamine in phosphate buffer (pH 6) at +550 mV from 40 to 170 mg L?1 with a limit of detection (S/N≥3) of 38 mg L?1. The practical linear range offered by this method suggests ideal use for spoilage detection in fermented foods. 相似文献
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The reaction of Cp(PPh3)NiCl (Cp = η5-C5H5) with PhSCH2Li gives Cp(PPh3)Ni(η1-CH2SPh) (I), which has been isolated as green crystals and characterized by elemental analysis, magnetic measurement, 1H NMR and mass spectroscopic investigations and by protolysis to form PhSCH3. Cp2Ni also reacts with PhSCH2Li in the presence of PPh3 to give I containing 5–10% of Cp(PPh3)NiSPh (II) and about 1% of [CpNiSPh]2 (III) as impurities. In the absence of PPh3, III is formed, with the release of ethylene and cyclopropane, even at a temperature of ?20°C. For comparison, II has been synthesized from Cp2Ni, PPh3 and LiSPh and from the reaction of III with PPh3.I decomposes in boiling benzene to give II (ca. 33%) and III (ca. 13%). The conversion of the thioanisolyl into thiophenolato complexes can be understood on assuming that {CpNi(η2-CH2SPh)} is formed as an unstable intermediate. 相似文献
138.
Dr. Ángel J. Jiménez Michael Sekita Dr. Esmeralda Caballero Dr. M. Luisa Marcos Dr. M. Salomé Rodríguez‐Morgade Prof. Dr. Dirk M. Guldi Prof. Tomás Torres 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(43):14506-14514
In a novel electron‐donor–acceptor conjugate, phthalocyanine (Pc) and perylenediimide (PDI) are connected through a trans‐platinum(II) diacetylide linker to yield Pc‐Pt‐PDI 1 . In the ground state, the presence of PtII disrupts the electronic communication between the two electroactive components, as revealed by UV/Vis spectroscopy and electrochemical studies. The photophysical behavior of 1 is compared with that of the corresponding Pc‐PDI electron‐donor–acceptor conjugate 2 in terms of charge separation and charge recombination. The insertion of PtII between Pc and PDI impacts the results in a longer‐lived Pc . +/PDI . ? radical ion‐pair state. In addition, the intermediately formed Pc triplet excited state is formed with higher quantum yields in 1 than in 2 . 相似文献
139.
Charles E. Nwankire Gerard G. Donohoe Xin Zhang Jonathan Siegrist Martin Somers Dirk Kurzbuch Ruairi Monaghan Maria Kitsara Robert Burger Stephen Hearty Julie Murrell Christopher Martin Martha Rook Louise Barrett Stephen Daniels Colette McDonagh Richard O’Kennedy Jens Ducrée 《Analytica chimica acta》2013
In this paper we report a centrifugal microfluidic “lab-on-a-disc” system for at-line monitoring of human immunoglobulin G (hIgG) in a typical bioprocess environment. The novelty of this device is the combination of a heterogeneous sandwich immunoassay on a serial siphon-enabled microfluidic disc with automated sequential reagent delivery and surface-confined supercritical angle fluorescence (SAF)-based detection. The device, which is compact, easy-to-use and inexpensive, enables rapid detection of hIgG from a bioprocess sample. This was achieved with, an injection moulded SAF lens that was functionalized with aminopropyltriethoxysilane (APTES) using plasma enhanced chemical vapour deposition (PECVD) for the immobilization of protein A, and a hybrid integration with a microfluidic disc substrate. Advanced flow control, including the time-sequenced release of on-board liquid reagents, was implemented by serial siphoning with ancillary capillary stops. The concentration of surfactant in each assay reagent was optimized to ensure proper functioning of the siphon-based flow control. The entire automated microfluidic assay process is completed in less than 30 min. The developed prototype system was used to accurately measure industrial bioprocess samples that contained 10 mg mL−1 of hIgG. 相似文献
140.
Dirk Steinhilber Torsten Rossow Dr. Stefanie Wedepohl Florian Paulus Dr. Sebastian Seiffert Prof. Dr. Rainer Haag 《Angewandte Chemie (International ed. in English)》2013,52(51):13538-13543
pH‐Cleavable cell‐laden microgels with excellent long‐term viabilities were fabricated by combining bioorthogonal strain‐promoted azide–alkyne cycloaddition (SPAAC) and droplet‐based microfluidics. Poly(ethylene glycol)dicyclooctyne and dendritic poly(glycerol azide) served as bioinert hydrogel precursors. Azide conjugation was performed using different substituted acid‐labile benzacetal linkers that allowed precise control of the microgel degradation kinetics in the interesting pH range between 4.5 and 7.4. By this means, a pH‐controlled release of the encapsulated cells was achieved upon demand with no effect on cell viability and spreading. As a result, the microgel particles can be used for temporary cell encapsulation, allowing the cells to be studied and manipulated during the encapsulation and then be isolated and harvested by decomposition of the microgel scaffolds. 相似文献