No abstract

Polymers of intrinsic microporosity (PIMs) are distinguished from other polymers in how the diffusion coefficients for light gases depend on their effective size, with a stronger size-selective trend for gases larger than He and H2.

Polymers of intrinsic microporosity (PIMs) have been identified as potential next generation membrane materials for the separation of gas mixtures of industrial and environmental relevance. Based on the exceptionally rigid methanopentacene (MP) structural unit, a Polymer of Intrinsic Microporosity (PIM-MP-TB) was designed to demonstrate high selectivity for gas separations. PIM-MP-TB was prepared using PIMs, PIM-MP-TB is prepared in four simple steps from a cheap starting material.

To elucidate the catalytic mechanism of cobalt(III)-benzonitrile and iron(III)--pivalonitrile hydratases, we have performed at density functional level a study using the cluster model approach. Computations were made in a protein framework. Following the suggestions given in a recent work on the analogous enzyme Fe(III)-NHase, we have explored the feasibility of a new working mechanism of examined enzymes. According to our results, after the formation of enzyme substrate complex, the reaction evolves toward product in only three steps. The first one is the nucleophilic attack, led by the -OH group of the αCys113-S-OH on the nitrile carbon atom, followed by the amide formation and by the enzyme restoring phase that our computations indicate as the most expensive step from the energetic point of view in both catalytic processes.