IR and raman spectra of two layered aluminium phosphates Co(en)3Al3P4O16.3H2O and

The FT IR and FT Raman spectra of Co(en)3Al3P4O16.3H2O (compound I) and [NH4]3[Co(NH3)6]3[Al2 (PO4)4]2.2H2O (compound II) are recorded and analysed based on the vibrations of Co(en)(3)3+, Co(NH3)(6)3+, NH4, Al-O-P, PO3, PO2 and H2O. The observed splitting of bands indicate that the site symmetry and correlation field effects are appreciable in both the compounds. In compound I, the overtone of CH2 deformation Fermi resonates with its symmetric stretching vibration. The NH4 ion in compound II is not free to rotate in the crystalline lattice. Hydrogen bonding of different groups is also discussed.     

IR and Raman spectra of two layered aluminium phosphates Co(en)3Al3P4O16 · 3H2O and [NH4]3[Co(NH3)6]3[Al2(PO4)4]2 · 2H2O

The FT IR and FT Raman spectra of Co(en)₃Al₃P₄O₁₆ · 3H₂O (compound I) and [NH₄]₃[Co(NH₃)₆]₃[Al₂(PO₄)₄]₂ · 2H₂O (compound II) are recorded and analysed based on the vibrations of Co(en)₃³⁺, Co(NH₃)₆³⁺, NH₄⁺, Al---O---P, PO₃, PO₂ and H₂O. The observed splitting of bands indicate that the site symmetry and correlation field effects are appreciable in both the compounds. In compound I, the overtone of CH₂ deformation Fermi resonates with its symmetric stretching vibration. The NH₄ ion in compound II is not free to rotate in the crystalline lattice. Hydrogen bonding of different groups is also discussed.     

Naphthalene Complexation by β-Cyclodextrin: Influence of Added Short Chain Branched and Linear Alcohols

Naphthalene forms 1 : 1 complexes with -cyclodextrin (-CD)in water. The binding constant is 377 ± 35 M^-1. Addition of linear or branched alcohols causes a reduction in the apparent strength of naphthalene binding (K_app) compared to the value in the absence of additives. For example, 1% 1-pentanol reduces K_app to 184 ± 31 M^-1. Branching does not alter K_app much for a given number of carbon atoms, e.g., it is 113 ± 9 M^-1for 2-pentanol and 116 ± 8 M^-1for 3-pentanol. The exception to this is tert-butanol for which K_app is 577 ± 40 M^-1. The variation in K_app as a function of [1-pentanol] yields values for the individual equilibrium constants contributing to K_app. This reveals that a ternary complex forms involving naphthalene, the CD and 1-pentanol. The constant for formation of the ternary complex is 99 ± 29 M^-2. NaI quenching of naphthalene fluorescence indicates that the CD cavity partially protects the naphthalene excited state fromthis water phase quencher. Interestingly, the Stern–Volmer constant is lower in the presence of 1-pentanol than in its absence, although there should be more unbound (and therefore more NaI accessible) naphthalene in the former system than in the latter. These apparently contradictory results are discussed in terms of ternary complex formation.     

Enantiodivergence in small-molecule catalysis of asymmetric phosphorylation: concise total syntheses of the enantiomeric D-myo-inositol-1-phosphate and D-myo-inositol-3-phosphate

Peptide-based catalysts have been found that catalyze the enantiodivergent phosphorylation of a meso myo-inositol-derived triol (1). The sequential screening of random peptide libraries, followed by the evaluation of a focused library, led to the identification of two peptides (2 and 24) that are complementary in producing enantiomeric D-myo-inositol-1-phosphate and D-myo-inositol-3-phosphate derivatives. The catalysts were then used to complete efficient total syntheses of both D-I-1P and D-I-3P in optically pure form. Additional information is gleaned from relative rate experiments that unambiguously show the catalysts to afford enantioselection through rate accelerative pathways with respect to simple achiral alkylimidazole catalysts. Furthermore, solvent effect studies show that the two enantiodivergent catalysts exhibit different tolerances of polar media. The systematic discovery of site-selective catalysts establishes a basis for future studies of chiral catalysts that differentiate unique functional groups in polyfunctional molecules.     

Ethylene tetramerization: a new route to produce 1-octene in exceptionally high selectivities

Linear alpha-olefins, such as 1-hexene and 1-octene, are important comonomers in the production of linear low-density polyethylene (LLDPE). The conventional method of producing 1-hexene and 1-octene is by oligomerization of ethylene, which yields a wide spectrum of linear alpha-olefins (LAOs). While there exists several processes for producing 1-hexene via ethylene trimerization, a similar route for the selective production of 1-octene has so far been elusive. We now, for the first time, report an unprecedented ethylene tetramerization reaction that produces 1-octene in selectivities exceeding 70%, using an aluminoxane-activated chromium/((R2)2P)2NR1 catalyst system.     

Catalytic asymmetric carbohydroxylation of alkenes by a tandem diboration/Suzuki cross-coupling/oxidation reaction

[reaction: see text] Chiral nonsymmetric 1,2-diboron adducts are generated by catalytic enantioselective diboration. Oxidation of these adducts provides 1,2-diols in good yield. Alternatively, 1,2-diboron compounds may be reacted, in situ, with aryl halides wherein the less hindered C-B bond participates in cross-coupling. The remaining C-B bond is then oxidized in the reaction workup thereby allowing for net asymmetric carbohydroxylation of alkenes in a tandem one-pot diboration/Suzuki coupling/oxidation sequence.     

Dynorphin A 1–17 biotransformation in inflamed tissue, serum and trypsin solution analysed by liquid chromatography–tandem mass spectrometry

Dynorphin A 1–17 (DYN A) is an endogenous neuropeptide that is of interest due to its diverse roles in analgesia, inflammation and addiction. Upon release, DYN A is subject to metabolism by a range of enzymes and its biotransformation is dependent on the site and environment into which it is released. In this study, we investigated the biotransformation of DYN A in rat inflamed tissue at pH?7.4 and 5.5, in rat serum and in trypsin solution. DYN A-porcine was incubated at 37?°C in each matrix over a range of incubation periods. The resultant fragments were separated using a C4 column and detected by mass spectrometry using total ion current mode. Incubation of DYN A in trypsin solution and in rat serum resulted in 6 and 14 fragments, respectively. Incubation in inflamed rat paw tissue occasioned 21 fragments at pH?7.4 and 31 fragments at pH?5.5. Secondary breakdown of some larger primary fragments was also observed in this study.     

Programmable large area digital microfluidic array with integrated droplet sensing for bioassays

We describe a new device concept for digital microfluidics, based on an active matrix electrowetting on dielectric (AM-EWOD) device. A conventional EWOD device is limited by the number of electrical connections that can be made practically, which restricts the number and type of droplet operations. In an AM-EWOD, the patterned electrodes of a conventional EWOD device are replaced by a thin film transistor (TFT) array, as found in a liquid crystal display (LCD), facilitating independent control of each electrode. The arrays can have many thousand individually addressable electrodes, are fully reconfigurable and can be programmed to support multiple simultaneous operations. Each element is 210 μm × 210 μm in size and contains a circuit that measures the electrical impedance of the liquid above it. This is used to determine the presence and size of a droplet, a method that can improve assay reliability and accuracy. This sensor provides feedback, error detection and closed loop control of an assay sequence. We describe the design, fabrication and testing of a 64 × 64 format AM-EWOD device with impedance sensor functionality. A colorimetric assay is implemented on the device and used to measure glucose in human blood serum. Results are compared with the same assay performed on a microtitre plate.     

How to Make Drugs Orally Active: A Substrate Template for Peptide Transporter PepT1

By building key structural features into hydrophilic drugs, they can be recognized by the PepT1 transporter system of the small intestine and rendered orally active. The model shown provides, for the first time, a 3D template for all known substrates of PepT1.     

Spin‐State Ordering on One Sub‐lattice of a Mononuclear Iron(III) Spin Crossover Complex Exhibiting LIESST and TIESST

The two‐step spin crossover in mononuclear iron(III) complex [Fe(salpm)₂]ClO₄ ? 0.5 EtOH ( 1 ) is shown to be accompanied by a structural phase transition as concluded from ⁵⁷Fe Mössbauer spectroscopy and single crystal X‐ray diffraction, with spin‐state ordering on just one of two sub‐lattices in the intermediate magnetic and structural phase. The complex also exhibits thermal‐ and light‐induced spin‐state trapping (TIESST and LIESST), and relaxation from the LIESST and TIESST excited states occurs via the broken symmetry intermediate phase. Two relaxation events are evident in both experiments, that is, two T(LIESST) and two T(TIESST) values are recorded. The change in symmetry which accompanies the TIESST effect was followed in real time using single crystal diffraction. After flash freezing at 15 K the crystal was warmed to 40 K at which temperature superstructure reflections were observed to appear and disappear within a 10 000 s time range. In the frame of the international year of crystallography, these results illustrate how X‐ray diffraction makes it possible to understand complex ordering phenomena.