Archive for March, 2007
Social Explanatory Style as a Foundation of Empathic Orientation
We examined whether peoples social explanations the explanatory frameworks they use to make sense of others behaviors and outcomes are tied to their social orientation, or the extent to which they demonstrate tendencies such as empathy and forgiveness. While evidence for a social explanatory style (i.e., a characteristic manner of explaining behavior across targets and contexts) was mixed, results demonstrated that social explanations interacted with epistemic motives (e.g., attributional complexity) to predict social orientation.
Solvation Controlled Luminescence of Sm(II) Complexes
Changes in solvation of samarium diiodide (SmI2) can significantly alter the interaction between a ligand and metal. Addition of the appropriate crown ether to SmI2 in acetonitrile not only stabilizes the ground state complex but also generates a highly luminescent complex. The advantage of direct excitation of lanthanide(II) complexes includes elimination of different deactivation pathways as well as the multi-step syntheses involved in preparing antenna ligands necessary for producing luminescent lanthanide(III) complexes. We demonstrate how controlling the coordination sphere of SmI2 through changes in solvation induces remarkable changes both in the ground and excited states. By providing a chelating ligand for SmI2 in a solvent incapable of displacing it significantly enhances the luminescent properties of Sm(II) by: 1.) encapsulating the metal through a strong metal-ligand interaction and 2) decreasing the frequency of solvent collision. This study led to the discovery of the longest reported excited-state lifetime for a Sm(II) complex in solution.
Role of Reactive Surfactants in Miniemulsion Polymerization
Reactive surfactants show a promising approach to reduce the negative effects where by the surfactant is chemically incorporated into the latex particles during the course of the polymerization so that desorption of the surfactant from the latex or migration in the resulting polymer film is impeded. One of its main characteristics is that reactive surfactant should be incorporated onto the polymer particles surfaces at the very end of the reaction process .Miniemulsion polymerization is therefore proposed as an alternative process to increase the amount of the surfactant incorporated on the particle surfaces and to minimize the amount of the buried surfactant since miniemulsion polymerize primarily via droplet nucleation mechanism. › Continue reading
Reversible Self-Assembly of Hydrophilic Inorganic Polyelectrolytes into Highly Conservative, Vesicle-like Structures
The hydrophilic polyoxometalate (POM) macroanions are inorganic polyelectrolytes which offer a direct connection between simple ions and organic polyelectrolytes. POM solutions are perfect model systems for studying polyelectrolyte solutions because they are identical in size, shape, mass and charges, with easily tunable charge density.
Many types of POM macroanions are highly soluble but undergo reversible self-assembly to form uniform, stable, soft, single-layer vesicle-like blackberry structures containing >1000 individual POMs in dilute solutions. The driving force of the blackberry formation is likely counterion-mediated attraction (like-charge attraction). The blackberry size can be accurately controlled by solvent quality, or the charge density on macroions. Many unexpected phenomena have been observed in these novel systems. Blackberry structures may be analogous to virus shell structures formed by capsid proteins.
References:
Nature, 2003, 426, 59; JACS, 2002, 124, 10942; 2003, 125, 312; 2004, 126, 16690; 2005, 127, 6942; 2006, 128, 10103.