Nitrile regio-synthesis by Ni centers on a siliceous surface: implications in prebiotic chemistry.

By means of quantum chemistry (PBE0/def2-TZVPP; DLPNO-CCSD(T)/cc-pVTZ) and small, but reliable models of Polyhedral Oligomeric Silsesquioxanes (POSS), an array of astrochemically-relevant catalysis products, related to prebiotic and origin of life chemistry, has been theoretically explored. In this work, the heterogeneous phase hydrocyanation reaction of an unsaturated CC bond (propene) catalyzed by a Ni center complexed to a silica surface is analyzed. Of the two possible regioisomers, the branched iso-propyl-cyanide is thermodynamically and kinetically preferred over the linear -propyl-cyanide ( = 200 K).

Usefulness of Electoral Models for COVID-19 Vaccine Distribution.

Purpose Of Review: In response to the COVID-19 pandemic, there has been a remarkably accelerated development of vaccines worldwide. However, an effective distribution system is crucial for vaccination at a national level. Ecuador was one of the first Latin American countries to be most severely affected by the pandemic.

Complex Organic Matter Synthesis on Siloxyl Radicals in the Presence of CO.

Heterogeneous phase astrochemistry plays an important role in the synthesis of complex organic matter (COM) as found on comets and rocky body surfaces like asteroids, planetoids, moons and planets. The proposed catalytic model is based on two assumptions: siliceous rocks in both crystalline or amorphous states show surface-exposed defective centers such as siloxyl (Si-O•) radicals; the second phase is represented by gas phase CO molecules, an abundant C building block found in space. By means of quantum chemistry; (DFT, PW6B95/def2-TZVPP); the surface of a siliceous rock in presence of CO is modeled by a simple POSS (polyhedral silsesquioxane) where a siloxyl (Si-O•) radical is present.

On the formation of phosphorous polycyclic aromatics hydrocarbons (PAPHs) in astrophysical environments.

The formation of phosphorous-containing polycyclic aromatic hydrocarbons (PAPHs) in astrophysical contexts is proposed and analyzed by means of computational methods [B3LYP-D3BJ/ma-def2-TZVPP, MP2-F12, CCSD-F12b and CCSD(T)-F12b levels of theory]. A "bottom-up" approach based on a radical-neutral reaction scheme between acetylene (CH) and the CP radical was used investigating: (a) the synthesis of the first PAPH (CHP) "phosphinine"; (b) PAPH growth by addition of CH to the CHP radical; (c) PAPH synthesis by addition reactions of one CP radical and nCH to a neutral PAH. Results show: (I) the formation of the phosphinine radical has a strong thermodynamic tendency (-133.