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Hydrolytically Stable (hydrolytically + stable)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

High-buffering capacity, hydrolytically stable, low-pI isoelectric membranes for isoelectric trapping separations

ELECTROPHORESIS, Issue 20 2004
Sanjiv Lalwani
Abstract Hydrolytically stable, low-pI isoelectric membranes have been synthesized from low-pI ampholytic components, poly(vinyl alcohol), and a bifunctional cross-linker, glycerol-1,3-diglycidyl ether. The low-pI ampholytic components used contain one amino group and at least two weakly acidic functional groups. The acidic functional groups are selected such that the pI value of the ampholytic component is determined by the pKa values of the acidic functional groups. When the concentration of the ampholytic component incorporated into the membrane is higher than a required minimum value, the pI of the membrane becomes independent of variations in the actual incorporation rate of the ampholytic compound. The new, low-pI isoelectric membranes have been successfully used as anodic membranes in isoelectric trapping separations with pH < 1.5 anolytes and replaced the hydrolytically less stable polyacrylamide-based isoelectric membranes. The new low-pI isoelectric membranes have excellent mechanical stability, low electric resistance, good buffering capacity, and long life time, even when used with as much as 50 W power and current densities as high as 33 mA/cm2 during the isoelectric trapping separations. [source]

Synthesis and Characterization of 1-Azido-2-Nitro-2-Azapropane and 1-Nitrotetrazolato-2-Nitro-2-Azapropane

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2006
Roland Boese
Abstract 1-Azido-2-nitro-2-azapropane (1) was synthesized in high yield from 1-chloro-2-nitro-2-azapropane and sodium azide. 1-Nitrotetrazolato-2-nitro-2-azapropane (2) was synthesized in high yield from 1-chloro-2-nitro-2-azapropane and silver nitrotetrazolate. The highly energetic new compounds (1 and 2) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (1H, 13C, 14N), elemental analysis and low-temperature single crystal X-ray diffraction. 1-Azido-2-nitro-2-azapropane (1) represents a covalently bound liquid energetic material which contains both a nitramine unit and an azide group in the molecule. 1-Nitrotetrazolato-2-nitro-2-azapropane (2) is a covalently bound room-temperature stable solid which contains a nitramine group and a nitrotetrazolate ring unit in the molecule. Compounds 1 and 2 are hydrolytically stable at ambient conditions. The impact sensitivity of compound 1 is very high (<1,J) whereas compound 2 is less sensitive (<6,J). [source]

Zn2+ Complexes of Di- and Tri-nucleating Azacrown Ligands as Base-Moiety-Selective Cleaving Agents of RNA 3,,5,-Phosphodiester Bonds: Binding to Guanine Base

CHEMBIOCHEM, Issue 11 2008
Qi Wang Dr.
Abstract The ability of the dinuclear Zn2+ complex of 1,4-bis[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L1) to promote the cleavage of the phosphodiester bond of dinucleoside-3,,5,-monophosphates that contain a guanine base has been studied over a narrow pH range from pH 5.8 to 7.2 at 90,°C. Comparative measurements have been carried out by using the trinuclear Zn2+ complex of 1,3,5-tris[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L2) as a cleaving agent and guanylyl-3,,5,-guanosine (5,-GpG-3,) as a substrate. The strength of the interaction between the cleaving agent and the starting material has been elucidated by UV spectrophotometric titrations. The speciation and binding mode have been clarified by potentiometric titrations with hydrolytically stable 2,- O -methylguanylyl-3,,5,-guanosine and 1H NMR spectroscopic measurements with guanylyl-3,,5,-guanosine. The results show that the guanine base is able to serve as a site for anchoring for the Zn2+,azacrown moieties of the cleaving agents L1 and L2, analogously to uracil base. The interaction is, however, weaker than with the uracil base and, hence, only the 5,-GpG-3, site (in addition to 5,-GpU-3, and 5,-UpG-3, sites) is able to markedly modulate the phosphodiester cleavage by the Zn2+ complexes of di- and trinucleating azacrown ligands containing an ether oxygen as a potential H-bond-acceptor site. [source]