An alternative and facile purification procedure of amidation and esterification reactions using a medium fluorous Mukaiyama reagent

A convenient methodology for the separation of a fluorous by-product using fluorous chemistry is described. A Mukaiyama coupling reagent bearing a medium fluorous tag, between 40% and 60% fluorine by weight, can be effectively separated from non-fluorous components by increasing the water content of the crude reaction mixture and subsequent filtration. Additional fluorous solid phase extraction is not necessary.     

Development of low cost pulmonary surfactants composed of a mixture of lipids or lipids-peptides using higher aliphatic alcohol or soy lecithin

The artificial pulmonary surfactant composition in the present study is characterized by a lipid mixture system composed of higher aliphatic alcohol, egg yolk phosphatidylcholine (egg PC), soy lecithin and higher aliphatic acid as the major components or a peptide-lipid mixture system composed of a combination of the lipid mixture system to which a peptide is added. Three peptides with amphiphilic surface-staying, membrane spanning, and both properties were designed and synthesized. The evaluation of pulmonary surfactant assay was performed by a hysteresis curve drawn upon the measurement for the surface tension-area curve with the Wilhelmy surface tensometer in vitro and the recovery of lung compliance for the pulmonary surfactant-deficient rat models in vivo. Lipid-mixture systems composed of octadecanol or soy lecithins containing no peptide were favorable hysteresis curves as compared with commercially available Surfacten((R)), but were not prominent. The peptide-lipid mixture systems composed of a combination of the lipid mixture of alkyl alcohol or soy lecithin to which peptides designed were added were desirable hysteresis curves similar to Surfacten((R)) and amphiphilic Hel 13-5 peptide-lipids mixture systems were much more effective than the lipid mixture system. Particularly, the recovery of lung compliance treated with hydrogenated soy lecithin-fractionated soy lecithin PC70-palmitic acid-peptide Hel 13-5 (40:40:17.5:2.5, w/w) was comparable to that with Surfacten((R)). Because the artificial pulmonary surfactant compositions of this study can be prepared at lower costs, they are useful for the treatment of respiratory distress syndrome and acute respiratory distress syndrome as well as for inflammatory pulmonary diseases, dyspnea caused by asthma, etc.     

Phase transitional behaviour of S-shaped oligomers incorporating biphenylene and cholesterol entities

A new series of symmetrical S-shaped oligomers 4,4′-bis[(5-cholesteryloxycarbonylpentyl alkoxy)hexyloxy]biphenyl consisting of outer spacers –(COCH₂)_n– as well as an inner spacer –(CH₂)₆– has been synthesised. Their liquid crystalline properties and phase transition temperatures with associated enthalpy changes are recorded. The outer spacers are varied from n = 5–8 to 10 and 11. The compounds with even spacer exhibit enantiotropic phase and oligomers with odd parity display monotropic phase. The oligomers with odd membered n = 5, 7 and 11 exhibit N* and SmC* phases upon cooling. Whilst upon heating, the homologues with even-numbered member n = 6 and 10 show N* phase and upon cooling, both compounds exhibit N* and SmC* phases. However, oligomer with outer spacer n = 8 displays enantiotropic N* and SmC* phases. The temperature range of N* phase for even and odd membered decreased as the outer spacers are increased. The odd–even effect has been found in the I–N* transition temperatures where the odd-parity oligomers exhibit lower values when compared to compounds of an even-parity series. The X-ray diffraction measurements reveal the appearance of SmC* phase that can be associated with the monolayer ordering of these oligomers.     

Synergistic Photobactericidal Activity Based on Ultraviolet‐A Irradiation and Ferulic Acid Derivatives

Ultraviolet‐A (UV‐A)‐mediated bactericidal activity was enhanced by combined treatment with trans‐ferulic acid (trans‐FA, compound 1 ) or its derivatives. Derivative compounds 4 and 10 contain a phenyl group or an l ‐tyrosine HCl tert‐butyl ester, respectively, linked to the carboxyl group of trans‐FA. Of the three compounds, 10 exhibited the highest synergistic activity in a photobactericidal assay based on treating Escherichia coli with a derivative compound and UV‐A irradiation (wavelength 350–385 nm). Inactivation of viable cells at a 4.9 J cm^?2 UV‐A fluence increased from 1.90 to 5.19 logs in the presence of 10 (100 μm ); a 4.95‐log inactivation was achieved with 10 (5 μm ) and a 7.4 J cm^?2 UV‐A fluence. Addition of antioxidants significantly suppressed photosynergistic bactericidal activity, suggesting that reactive oxygen species (ROS) are involved in the combined bactericidal mechanism. Flow cytometry revealed that combined treatment with UV‐A and compound 10 , which showed the highest photobactericidal activity, generates an excess of oxidative radicals in bacterial cells. The bactericidal activity of compound 10 may be due to electrostatic interaction between the molecule's cationic moiety and the cell surface, followed by amplification of ROS generation in the cells.     

Bifacial Base‐Pairing Behaviors of 5‐Hydroxyuracil DNA Bases through Hydrogen Bonding and Metal Coordination

A novel bifacial ligand‐bearing nucleobase, 5‐hydroxyuracil ( U^OH ), which forms both a hydrogen‐bonded base pair ( U^OH –A) and a metal‐mediated base pair ( U^OH –M– U^OH ) has been developed. The U^OH –M– U^OH base pairs were quantitatively formed in the presence of lanthanide ions such as Gd^III when U^OH – U^OH pairs were consecutively incorporated into DNA duplexes. This result established metal‐assisted duplex stabilization as well as DNA‐templated assembly of lanthanide ions. Notably, a duplex possessing U^OH –A base pairs was destabilized by addition of Gd^III ions. This observation suggests that the hybridization behaviors of the U^OH ‐containing DNA strands are altered by metal complexation. Thus, the U^OH nucleobase with a bifacial base‐pairing property holds great promise as a component for metal‐responsive DNA materials.     

A chromium(III) bis-acetylide complex containing a trans-diethyl-ethylenedithio-substituted tetrathiafulvalene (TTF) derivative: synthesis,crystal structures,and magnetic properties

A new Cr(III) bis-acetylide complex containing redox-active ethynyl-substituted 4-methyl-4′,5′-trans-diethyl-ethylenedithio-tetrathiafulvalene, [Cr(III)cyclam(C≡C-MeEt₂EDT-TTF)₂]ⁿ⁺ ([1]ⁿ⁺) was synthesized. The crystal structures of two salts, [1][Ni(dmit)₂] (dmit?=?2-thioxo-1,3-dithiole-4,5-dithiolate) and [1][Ni(mnt)₂]₃ (mnt?=?maleonitriledithiolate), were determined by single-crystal X-ray diffraction. In the crystal of [1][Ni(dmit)₂], the trans-diethyl group of [1]⁺ is in the axial position and prevents π-stacking of the TTF units, resulting in a negligibly weak spin–spin interaction between Cr³⁺ and [Ni(dmit)₂]^?. In contrast, in [1][Ni(mnt)₂]_3, the trans-diethyl group is in the equatorial position in [1][Ni(mnt)₂]₃ owing to the strong attractive force between the π-stacked TTF⁺ units and the [Ni(mnt)₂]^? anions. This π-stacking has a significant effect on the magnetic property of [1] [Ni(mnt)₂]₃. The π-stacked TTF⁺ units and [Ni(mnt)₂]^? anions behave approximately as a one-dimensional S?=?1/2 antiferromagnetic chain connecting the spins of Cr³⁺ antiferromagnetically.

     

Study of the Complexation of Protactinium(V) with EDTA

Journal of Solution Chemistry - The complex formation of protactinium(V) with ethylenediaminetetraacetic acid (EDTA) was studied at tracer concentration...     

A high-copy-number plasmid capable of replication in thermophilic cyanobacteria

A 2.5 kb high-copy-number plasmid, pM A4 in thermophilic cyanobacterium Synechococcus sp. M A4 was isolated and characterized to develop a genetic engineering system for thermophilic cyanobacteria. The copy number of pM A4 was determined to be by densitometry about 350/cell. The pM A4 may be a type of rolling-circle plasmid, because a possible rep gene encoding 34 k D-protein and a consensus sequence of a double-stranded origin nick site of rolling circle plasmids were found in the pM A4 sequence. The pM A4 was electro-introduced into another thermophile, Synechococcus sp. MA 19, which is the strongest poly-β-hydroxybutyrate (PHB) accumulator in photoau totrophic organisms. The pM A4 was incorporated and retained in MA 19. These results indicate that pM A4 could be developed as a useful vector for thermophilic cyanobacteria.     

Universal Form of Stochastic Evolution for Slow Variables in Equilibrium Systems

Nonlinear, multiplicative Langevin equations for a complete set of slow variables in equilibrium systems are generally derived on the basis of the separation of time scales. The form of the equations is universal and equivalent to that obtained by Green. An equation with a nonlinear friction term for Brownian motion turns out to be an example of the general results. A key method in our derivation is to use different discretization schemes in a path integral formulation and the corresponding Langevin equation, which also leads to a consistent understanding of apparently different expressions for the path integral in previous studies.