Robust syndiotactic polystyrene films, presenting a suitable nanoporous host crystalline phase, are able to transfer, amplify, and memorize the chirality of nonracemic low-molecular-mass molecules. In fact, after temporary exposure to volatile nonracemic guests, the polymer films present intense induced circular dichroism (ICD) phenomena. These ICD phenomena are associated with the temporary formation of polymer/guest cocrystalline phases.

No abstract

No abstract

The syntheses of low‐molecular‐weight polyethylene (PE), in the presence of catalysts based on five different metallocene frameworks, have been compared. High yields and low molecular masses, typical of industrially relevant PE waxes, can be easily achieved by using overpressure of hydrogen. Particularly suitable for the production of PE waxes are catalytic systems based on the C2 symmetric rac‐dimethyl‐silyl‐bis‐(2‐methyl‐4‐phenyl‐1‐indenyl)‐zirconium dichloride (1) and the C2v symmetric bis‐cyclopentadienyl‐zirconium dichloride (5). The wax yields can be substantially increased by increasing the MAO/Zr molar ratio. The control of the PE molecular weight allows an easy control of physical properties. In fact, as Mn increases in the range 103–104 g/mol, the degree of crystallinity decreases from nearly 85 to 60% while the melting temperature increases from 125°C up to 135°C. Copyright © 2010 John Wiley & Sons, Ltd.

The self-assembly properties of the proximal p-tert-butylcalix[4]dihydroquinone compound have been studied to investigate the role played by crystallization conditions in driving the formation of a previously reported cubic porous framework. In chloroform and anhydrous ethyl acetate, the mutual inclusion of the tert-butyl groups is favored, leading to the cubic porous structure; otherwise, in the presence of a higher water amount, the OH groups provide H-bonds with bridging water molecules and a new triclinic crystal structure is obtained, in which the calixarene molecules include chloroform inside their cavities. By exposing a cubic/triclinic powder mixture to acetonitrile vapors, a new monoclinic chiral crystal structure is obtained by supramolecular assembly of calixarene, acetonitrile, and water molecules with the formation of single handed helices