On the ultrafast charge migration dynamics in isolated ionized halogen, chalcogen, pnicogen, and tetrel bonded clusters

Theoretical Study on the Aza-Diels-Alder Reaction Catalyzed by PHCl2 Lewis Acid via Pnicogen Bonding

The reaction mechanism of the Aza-Diels-Alder (A-D-A) cycloaddition reaction between X₂C═NNH₂, where X = H, F, Cl, Br, and 1,3-butadiene catalyzed by a PHCl₂ Lewis acid was characterized using density functional theory calculations. The influences of various substituents of X on the studied reaction were analyzed using the activation strain model (ASM), which is also termed as the distortion-interaction model. Calculations showed that the smallest and largest values of the activation energies belong to the substituents of F and Br, respectively. The activation energy of the studied reactions was decreased within 8.6 kcal·mol^-1 in the presence of PHCl₂ catalyst. Investigations showed that the pnicogen bonding is adequately capable of activating the A-D-A reaction. The quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis were implemented to understand the nature of C_4,Cbut···C_XIm and C_1,Cbut···N_XIm bonds at the TS structures. Additionally, the energy decomposition analysis (EDA) based on the ETS-NOCV scheme was used to characterize the nature of C_4,Cbut···C_XIm and C_1,Cbut···N_XIm bond. The results of the study mirror the fact that the PHCl₂ Lewis acid may be suggested as a simple suitable catalyst for experimental studies on the A-D-A reactions.

Molecular attochemistry in non-polar liquid environments: ultrafast charge migration dynamics through gold-thiolate and gold-selenolate linkages

Molecular attosecond science has already started contributing to our fundamental understanding of ultrafast purely electron dynamics in isolated molecules under vacuum. Extending attosecond science to the liquid phase is expected to offer new insight into the influence of a surrounding solvent environment on the attosecond electron dynamics in solvated molecules. A systematic theoretical investigation of the attochemistry of solvated molecules would help one design attosecond experiments under ambient conditions to explore the attochemistry in a liquid environment. With this goal in mind, for the first time, we have explored the attochemistry of molecules surrounded by different non-polar solvent environments. For this work, we have focused on the attosecond charge conduction through gold-thiolate and gold-selenolate linkages following the vertical ionization of the S/Se(CH₃)-CH₂-phenyl-X unit anchored to a gold dimeric cluster (Au₂), where X represents either a strong electron donating N(CH₃)₂ group or a strong electron withdrawing NO₂ group. To model solvation effects on the attochemistry of molecules containing gold-chalcogen linkages, we have used an implicit solvent model (Polarizable Continuum Model) under the density functional theory (DFT) formalism for non-polar solvents. We have found that the charge migration time scale in molecules becomes faster in the presence of the solvent environment as compared to that under vacuum. Charge oscillation does not damp quickly in molecules surrounded by the solvent environment as compared to that under vacuum. Furthermore, the direction of the charge migration may change in molecules when they are surrounded by the solvent environment as compared to that under vacuum. Thus, the present work has laid the foundation, for the first time, for thinking of the attochemistry into the realm of liquids.