Synthesis of poly[2-(perfluorooctyl)ethyl acrylate-<Emphasis Type="Italic">co</Emphasis>-poly(ethylene glycol) methacrylate] and its control of enzyme activity in supercritical carbon dioxide

Poly[2-(perfluorooctyl)ethyl acrylate-co-poly(ethylene glycol) methacrylate], P(POA-co-PEGm) was prepared as a new surfactant for scCO₂. The random copolymer was obtained by the radical polymerization of 2-(perfluorooctyl)ethyl acrylate (POA) and poly(ethylene glycol) methacrylate (PEGm) in DMF. The molar ratio of the POA and PEGm units in the copolymer was POA/PEGm = 0.972/0.028 by ¹H NMR. The molecular weight and molecular weight distribution were estimated by size exclusion chromatography to be Mn = 133,000 and Mw/Mn = 8.25, respectively. It was suggested that the copolymer formed micellar aggregates with the cores of the PEGm chains in scCO₂, based on the analyses of the copolymer in hexafluorobenzene by ¹H NMR and dynamic light scattering. The copolymer was soluble in scCO₂ and had a cloud point at a much higher pressure than the critical pressure. It was found that the copolymer solubilized CO₂-insoluble proteins such as bovine serum albumin and subtilisin Carlsberg in scCO₂. The solubility of the copolymer was not influenced by the presence of the proteins; however, the solubility decreased in the presence of a small amount of water along with the protein. The activity of the subtilisin slightly decreased when only placed in scCO₂, whereas a marked decrease in the activity was observed for the subtilisin in the presence of the copolymer in scCO₂. The subtilisin activity decreased as the CO₂ pressure increased.     

Functionalization of a Single C−F Bond of Trifluoromethylarenes Assisted by an ortho-Silyl Group Using a Trityl-Based All-in-One Reagent with Ytterbium Triflate Catalyst

Catalytic thiolation and azidation of a single C−F bond of trifluoromethylarenes were achieved assisted by an ortho-silyl group with all-in-one reagents to generate a trityl cation and nucleophiles. The reactions catalyzed by ytterbium triflate efficiently afforded a wide variety of difluoromethylenes avoiding the further C−F bond cleavage, by virtue of the mild conditions without the generation of a Brønsted acid.     

Compressed holographic particle tracking velocimetry for microflow measurements

Optical Review - We have established a holographic particle tracking velocimetry (HPTV) technique based on compressed sensing (CS) for measurement of the velocity field of microflows in this study....     

A Fluorescence Sensor Array Based on Zinc(II)-Carboxyamidoquinolines: Toward Quantitative Detection of ATP**

The newly prepared fluorescent carboxyamidoquinolines ( 1 – 3 ) and their Zn(II) complexes ( Zn@1-Zn@3 ) were used to bind and sense various phosphate anions utilizing a relay mechanism, in which the Zn(II) ion migrates from the Zn@1-Zn@3 complexes to the phosphate, namely adenosine 5’-triphosphate (ATP) and pyrophosphate (PPi), a process accompanied by a dramatic change in fluorescence. Zn@1-Zn@3 assemblies interact with adenine nucleotide phosphates while displaying an analyte-specific response. This process was investigated using UV-vis, fluorescence, and NMR spectroscopy. It is shown that the different binding selectivity and the corresponding fluorescence response enable differentiation of adenosine 5’-triphosphate (ATP), adenosine 5’-diphosphate (ADP), pyrophosphate (PPi), and phosphate (Pi). The cross-reactive nature of the carboxyamidoquinolines-Zn(II) sensors in conjunction with linear discriminant analysis (LDA) was utilized in a simple fluorescence chemosensor array that allows for the identification of ATP, ADP, PPi, and Pi from 8 other anions including adenosine 5’-monophosphate (AMP) with 100 % correct classification. Furthermore, the support vector machine algorithm, a machine learning method, allowed for highly accurate quantitation of ATP in the range of 5–100 μM concentration in unknown samples with error <2.5 %.     

Aurophilic Interactions in Multi-Radical Species: Electronic-Spin and Redox Properties of Bis- and Tris-[(Nitronyl Nitroxide)-Gold(I)] Complexes with Phosphine-Ligand Scaffolds

Multinuclear Au^I complexes with two or three nitronyl nitroxide-2-ide radical anion and phosphine-ligand scaffolds, (NN-Au)₂-1 o , (NN-Au)₂-1 m , and (NN-Au)₂-1 p , have been synthesized to investigate the influence of Au^I−Au^I (aurophilic) interactions on the properties of multispin molecular systems. The desired complexes were successfully prepared in moderate yields in a one-pot synthesis from the corresponding phosphine ligand, Au^I source, parent NN, and sodium hydroxide. Among the prepared complexes, (NN-Au)₂-1 o , in which an aurophilic interaction was clearly observed by crystal structure analysis, showed characteristic spin−spin interactions, electrochemical properties, and solvatochromic behavior. The results from theoretical calculations also suggested that the differences in properties between complex (NN-Au)₂-1 o and the other complexes are due to intramolecular aurophilic interactions.     

An arrayed-window microfluidic device for observation of mixed nanoparticles with an X-ray free-electron laser

Optical Review - A microfluidic device was developed for coherent diffraction imaging using an X-ray free-electron laser (XFEL-CDI). Liquid samples, which are separately packed in reservoirs of the...     

Synthesis of All Stereoisomers of RK460 and Evaluation of Their Activity and Selectivity as Abscisic Acid Receptor Antagonists

The PYR/PYL/RCAR protein families have recently emerged as receptors of the phytohormone abscisic acid (ABA, 1 ), which regulates plant responses to environmental stress. These families have multiple members with different physiological actions, and so selective agonists or antagonists are needed both as tools to elucidate functional differences and as lead compounds for agrochemicals. We previously identified RK460 (rac- 3 a ) as a PYR1-selective antagonist, and showed that it possesses five stereocenters on a 6,5-cis-bicyclo skeleton. Here, we synthesized all the stereoisomers of RK460 and evaluated their activity towards a panel of receptors. Relative stereochemistry as well as absolute stereochemistry was important for selective action.     

Synthesis of a new 2‐amino‐glycan,poly‐(1→6)‐α‐D‐mannosamine,by ring‐opening polymerization of 1,6‐anhydro‐mannosamine derivatives

A stereoregular 2‐amino‐glycan composed of a mannosamine residue was prepared by ring‐opening polymerization of anhydro sugars. Two different monomers, 1,6‐anhydro‐2‐azido‐mannose derivative ( 3 ) and 1,6‐anhydro‐2‐(N, N‐dibenzylamino)‐mannose derivative ( 6 ), were synthesized and polymerized. Although 3 gave merely oligomers, 6 was promptly polymerized into high polymers of the number‐average molecular weight (M_n) of 2.3 × 10⁴ to 2.9 × 10⁴ with 1,6‐α stereoregularity. The differences of polymerizability of 3 and 6 from those of the corresponding glucose homologs were discussed. It was found that an N‐benzyl group is exceedingly suitable for protecting an amino group in the polymerization of anhydro sugars of a mannosamine type. The simultaneous removal of O‐ and N‐benzyl groups of the resulting polymers was achieved by using sodium in liquid ammonia to produce the first 2‐amino‐glycan, poly‐(1→6)‐α‐D ‐mannosamine, having high molecular weight through ring‐opening polymerization of anhydro sugars.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012