Polar Electrophoresis: Shape of Two-Dimensional Maps Is as Important as Size

The performance of two-dimensional electrophoresis in conventional gels in Cartesian coordinates (2-DE) vs. polar coordinates (2-PE) is here evaluated. Although 2-DE is performed in much longer Immobiline gels in the first dimension (17 cm) vs. barely 7-cm in 2-PE, an equivalent resolving power is found. Moreover, due to the possibility of running up to seven Immobiline strips in the radial gel format, the reproducibility of spot position is seen to be higher, this resulting in a 20% higher matching efficiency. As an extra bonus, strings of “isobaric” spots (i.e. polypeptides of identical mass with different pI values) are more resolved in the radial gel format, especially in the 10 to 30 kDa region, where the gel area fans out leaving extra space for spot resolution. In conclusion, this novel gel format in the second dimension of 2D gels is seen as an important improvement of this technique, still one of the most popular in proteome analysis

C2 Symmetrical Double Chromophores: Cooperativity Effects in Lanthanide Ion Complexation

We describe the synthesis and characterization of C2 symmetrical double chromophores, in which two identical chromophores are linked through ethylene glycol spacers of increasing lengths. The complexation ability of the trans stereopure form for each diastereoisomeric pair showed how the two chromophores, when the spacer unit is comprised of a diethylene or a triethylene glycol moiety, are able to interact in a positive way, stabilizing the resulting complexes when compared with single chromophore analogous compounds

Malonate Crown Ethers as Building Blocks for Novel D-pi-A Chromophores

A series of new crown ethers, Incorporating a malonate ester functionality, have been synthesized and derivatized with pi-electron rich aldehydes; to give, conjugated, extended "push-pull" compounds. Their ability to bind Lewis acid-like metal cations, such as Mg2+ and Eu3+, has been characterized, and the relative stability constants are presented. When the metal cation is bound to the malonate moiety within the crown ether cavity, the D-pi-A character of the molecular structure is greatly enhanced

Synthesis and structure determination of 1,4,7,11,14,17,21,24,27-nonaoxatriacontan-8,10,18,20,28,30-esaone

The title compound crystallizes in the trigonal space group R-3, with unit-cell parameters: a = 23.261(4), c = 9.537(2) angstrom; lambda(MoK alpha) = 0.71073 angstrom, V = 4469(2) angstrom(3), and Z = 6. The structure has been solved by direct methods using X-ray diffraction techniques. The final reliability index for the computed structure is 0.0826 for 929 observed reflections and 121 refined parameters. Crown ether adopts an almost circular shape and macrocycles are piled up in a columnar arrangement forming tubular nanochannels. The channels are filled with guest CDCl3 molecules, characterised by rotational disorder

COPPER(II) IN ORGANIC-SYNTHESIS .9. THE COPPER(II)-CATALYZED MICHAEL REACTION AS A ROUTE TO POLYSUBSTITUTED BENZENE-DERIVATIVES

THE COPPER(II)-CATALYZED MICHAEL REACTION AS A ROUTE TO POLYSUBSTITUTED BENZENE-DERIVATIVE

Solvent Effect as the Result of Frontier Molecular Orbital Interaction. VII. The Retro-Diels-Alder Reaction

The solvent effect on the retro-Diels-Alder (R.D.A.) reaction of 1,4,4a-9a-tetrahydro-4a-methyl-1(1α,4α,4aα,9aα)-1,4-methanoanthrac ene-9,10-dione to 2-methyl-1,4-naphthoquinone and cyclopentadiene was investigated kinetically in 16 solvents. The hyperbolic relationship between the kinetic data and the Acceptor Number of the solvents is strong evidence that the solvent acts as an electrophile which lowers the activation energy of the reaction. Furthermore when these rats constants are plotted vs those of the previously investigated Diels-Alder (D.A.) reaction of 1,4-napthhoquinone and 2,3-dimethylbutadiene, a linear relationship is obtained. The linearity of the graph is a good indication that the nature of the solvent effects is the same in both D.A. and R.D.A. reactions. The above relationships and the thermodynamic parameters strongly suggest that the R.D.A. reaction is a 'late transition state' pericyclic reaction whose solvent effect derives from a specific interaction between the solvent and the product