Synthesis, structure and luminescence properties of Cu(ii), Zn(ii) and Cd(ii) complexes with 4'-terphenylterpyridine

The complexes [M(tptpy)(2)](ClO(4))(2) (M = Zn(ii) (1), Cd(ii) (2), and Cu(ii) (3)); tptpy = 4'-[1,1':4',1']terphenyl-4'-yl-[2,2':6',2']terpyridine = 4'-terphenylterpyridine) have been synthesized, structurally characterized by X-ray crystallography and subjected to preliminary luminescence studies. In the crystalline state, all the metal ions have an N(6) coordination sphere of distorted octahedral geometry and the structures of the Zn(ii) and Cd(ii) complexes are isomorphous but differ from that of the Cu(ii) complex, which also differs from the other two in that it is non-emissive. The structure determinations show that aromatic-aromatic interactions involving both the terpyridine heads and the terphenyl tails are important factors influencing the crystalline array. The emission spectra of the Zn(ii) and Cd(ii) complexes are very similar and show a considerable red-shift of the emission maximum compared to that of the free ligand.     

CombinedB → X s Ψ andB → X s ν c decays as a test of factorization

We calculate the inclusive decaysB → X _s Ψ andB → X _s ν _c using factorization assumption. To investigate the bound state effect of the decaying B meson in these inclusive decays we take into account the motion of theb quark using a Gaussian momentum distribution model. The resulting correction to free quark decay approximation is around 6% at most. Utilizing a potential model evaluation of the ratio of the decay constantsf _νc ²/f _Ψ ², it is shown that the ratioR = Γ(B → X _sν_c)/Γ(B → X_sΨ) can be used a possible test of factorization assumption.     

Analysis of classes of compounds of environmental concern: III. Organochlorine pesticides

Forty five organochlorine pesticides (currently listed in EPA Method 8081A) have been chromatographed on DB-5/DB-1701 and SPB-5/SPB-1701 column pairs which were in each case connected to an inlet splitter and separate electron capture detectors. Thirteen additional compounds were evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8081A. Method reproducibility and linearity are discussed, and results are presented for extracts of six real samples spiked with fifteen organochlorine pesticides and analyzed using the dual-column, dual-detector arrangement.     

Chemical synthesis of 23 kDa glycoprotein by repetitive segment condensation: a synthesis of MUC2 basal motif carrying multiple O-GalNAc moieties

Peptide thioester corresponding to a MUC2 tandem repeat unit, which retains seven GalNAc moieties, was prepared by the Fmoc method followed by the low TfOH treatment to remove benzyl groups at the carbohydrate portions. The glycosylated peptide thioester was then consecutively joined by the activation of a thioester group by silver ions to obtain a MUC2 tandem repeat model composed of 141 amino acids with 42 GalNAc moieties.     

Conformational analysis of 1,2-dimethoxyethane and 1,2-diphenyloxyethane incorporated in nematic liquid crystals

Abstract

The conformations of flexible chain molecules incorporated in a nematic environment have been investigated. The phase behaviours and orientational characteristics of 1,2-dimethoxyethane (DME) dissolved in 4′-methoxybenzylidene-4-n-butylaniline at low solute mol fraction have been reported in our previous paper. In this work, proton–proton and carbon–carbon dipolar coupling constant measurements were attempted in addition to ²H NMR observations of quadrupolar splittings. These conformation-dependent properties were analysed according to the rotational isometric state (RIS) simulation scheme previously proposed. Our treatment rests on the assumption that the molecular axis of the chain should tend to align along the nematic field. Studies were further extended to a mixture of 1,2-diphenyloxyethane (DPE) with a nematic liquid crystal, 4,4′-azoxyanisole. Replacement of the terminal methyl groups in DME by phenyl groups leads to DPE. The results of the analysis indicate that the fraction of elongated conformers such as ttt tends to increase significantly on going from the isotropic to the liquid crystalline solution: DME; 9·4 to 15·6 per cent and DPE; 12·3 to 20·0 per cent. The tgt form (tg ⁺ t or tg ^? t) is the lowest-energy arrangement of these molecules. The fraction of this conformer also increases in DPE (26·8 to 40·0 per cent), while it decreases in DME (25·7 to 18·8 per cent). The conformational distributions of chain molecules were found to remain invariant over the range of concentration (0·5–6·0 mol per cent) and temperature (22·0–44·5°C) studied. It has been concluded that the observed variation of proton dipolar and deuterium quadrupolar couplings with concentration and temperature mainly arises from the orientational order of the molecular axis, which varies sensitively with the alignment of the surrounding solvent molecules. These results suggest that flexible chains are also participating in the nematic interaction by adjusting their configurations so as to enhance favourable interactions and suppress unfavourable steric repulsions when accommodated in an anisotropic potential field.     

A highly practical instant catalyst for cyclotrimerization of alkynes to substituted benzenes

[reaction: see text] A 2-(2,6-diisopropylphenyl)iminomethylpyridine (1a)/CoCl(2).6H(2)O/Zn reagent has been developed as an effective instant catalyst for the intra- and intermolecular cyclotrimerization of alkynes to substituted benzenes, making the method extremely practical since the reagent, 1a/CoCl(2).6H(2)O/Zn, is inexpensive and easy to handle and the reaction is less sensitive to moisture and is reasonably general.     

Tetraspanin CD9 modulates ADAM17-mediated shedding of LR11 in leukocytes

LR11, also known as SorLA or SORL1, is a type-I membrane protein from which a large extracellular part, soluble LR11 (sLR11), is released by proteolytic shedding on cleavage with a disintegrin and metalloproteinase 17 (ADAM17). A shedding mechanism is presumed to have a key role in the functions of LR11, but the evidence for this has not yet been demonstrated. Tetraspanin CD9 has been recently shown to regulate the ADAM17-mediated shedding of tumor necrosis factor-α and intercellular adhesion molecule-1 on the cell surface. Here, we investigated the role of CD9 on the shedding of LR11 in leukocytes. LR11 was not expressed in THP-1 monocytes, but it was expressed and released in phorbol 12-myristate 13-acetate (PMA)-induced THP-1 macrophages (PMA/THP-1). Confocal microscopy showed colocalization of LR11 and CD9 proteins on the cell surface of PMA/THP-1. Ectopic neo-expression of CD9 in CCRF-SB cells, which are LR11-positive and CD9-negative, reduced the amount of sLR11 released from the cells. In contrast, incubation of LR11-transfected THP-1 cells with neutralizing anti-CD9 monoclonal antibodies increased the amount of sLR11 released from the cells. Likewise, the PMA-stimulated release of sLR11 increased in THP-1 cells transfected with CD9-targeted shRNAs, which was negated by treatment with the metalloproteinase inhibitor GM6001. These results suggest that the tetraspanin CD9 modulates the ADAM17-mediated shedding of LR11 in various leukemia cell lines and that the association between LR11 and CD9 on the cell surface has an important role in the ADAM17-mediated shedding mechanism.     

Hydrogen bonding and mechanical properties of thin films of polyether-based polyurethane-silica nanocomposites

Two series of thin films of polyether-based polyurethane-silica nanocomposites having hard segment content of 51% and 34% and different concentrations of SiO₂ nanoparticles (0, 0.5, 1.0 and 3.0 vol.%) have been prepared. Infrared linear dichroic (LDIR) ratio, mechanical and differential scanning calorimetry (DSC) measurements were performed in order to determine the influence of hydrogen bonding on their mechanical and thermal properties. The degree of phase separation (DPS) and orientational functions in dependence on strain were calculated from the polarized IR spectra. The presence of silica nanoparticles gives rise to significant differences in the mechanical (stress-strain) properties of the nanocomposites with regard to the pure polymer. The nanocomposite thin films with lower hard segment content (HSC) displayed decreased stiffness and tensile and increased elongation at break in comparison to the nanocomposites with higher HSC. There was no distinctive influence of nanoparticles on the glass transition temperatures of soft segments. Nanosilica significantly affected the melting behavior of the hard phase only in samples with higher HSC.     

Determination of fluoxetine and norfluoxetine in rat brain microdialysis samples following intraperitoneal fluoxetine administration

Fluoxetine (FLX) and the N-desmethyl metabolite, norfluoxetine (NFLX) in rat brain microdialysis samples were determined by high-performance liquid chromatography (HPLC) with fluorescence detection using pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). In vitro experiment showed that the relative recovery of FLX across microdialysis membrane was enhanced by adding β-cyclodextrin (β-CD) or β-CD polymer to microdialysis perfusion fluid. The perfusion fluid containing β-CD polymer, which has polymeric glyceryl linkers attached to the hydroxyl group, gave the better recovery with satisfactory precisions. Using 1% β-CD polymer in Ringer’s solution as the perfusate, in vivo rat brain microdialysis experiment on intraperitoneal administration of FLX (10 mg/kg) to rats was carried out. The fluorescence peaks of FLX and NFLX appeared later than 30 min after the administration of FLX, and then, gradually increased with time. Two hours later, FLX reached a plateau level, but NFLX slowly increased, and at 24-48 h, NFLX levels were higher than FLX levels. These data suggest that long distributions of FLX and the potent metabolite, NFLX, in brain contributed to the long-term drug actions in vivo.