scholarly journals Electron Spin Densities and Density Functional Approximations: Open-Shell Polycyclic Aromatic Hydrocarbons as Case Study

2020 ◽  
Vol 16 (6) ◽  
pp. 3567-3577 ◽  
Author(s):  
Marika Savarese ◽  
Éric Brémond ◽  
Ilaria Ciofini ◽  
Carlo Adamo
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Electron Spin ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Open Shell ◽  
Polycyclic Aromatic ◽  
Spin Densities

scholarly journals Exploitation of Baird Aromaticity and Clar’s Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons

Chemistry ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 532-549
Author(s):  
Felix Plasser
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Materials Science ◽  
Chemical Shifts ◽  
Qualitative Description ◽  
Triplet States ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four biphenylene-derived PAHs finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). The results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.

Concentrations of polycyclic aromatic hydrocarbons and trace elements in Arctic soils: A case-study in Svalbard

2017 ◽  
Vol 159 ◽  
pp. 202-211 ◽  
Author(s):  
Montse Marquès ◽  
Jordi Sierra ◽  
Tatiana Drotikova ◽  
Montse Mari ◽  
Martí Nadal ◽  
...  
Keyword(s):  
Trace Elements ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Arctic Soils ◽  
Polycyclic Aromatic

scholarly journals How to add a five-membered ring to polycyclic aromatic hydrocarbons (PAHs) – molecular mass growth of the 2-naphthyl radical (C10H7) to benzindenes (C13H10) as a case study

2019 ◽  
Vol 21 (30) ◽  
pp. 16737-16750 ◽  
Author(s):  
Long Zhao ◽  
Matthew Prendergast ◽  
Ralf I. Kaiser ◽  
Bo Xu ◽  
Utuq Ablikim ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Molecular Mass ◽  
Aromatic Hydrocarbons ◽  
Membered Ring ◽  
Growth Processes ◽  
Mass Growth ◽  
Aryl Radicals ◽  
Polycyclic Aromatic

The reaction of aryl radicals with allene/methylacetylene leads to five-membered ring addition in PAH growth processes.

scholarly journals Exploitation of Baird Aromaticity and Clar's Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons

2021 ◽  
Author(s):  
Felix Plasser
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Materials Science ◽  
Chemical Shifts ◽  
Qualitative Description ◽  
Triplet States ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four PAHs based on the biphenylene motif finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). These results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.

Hydrogenated polycyclic aromatic hydrocarbons (HnPAHs) as catalysts for hydrogenation reactions in the interstellar medium: a quantum chemical model

2019 ◽  
Vol 21 (22) ◽  
pp. 12012-12020 ◽  
Author(s):  
Ricardo M. Ferullo ◽  
Carolina E. Zubieta ◽  
Patricia G. Belelli
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Quantum Chemical ◽  
Density Functional ◽  
Activation Barrier ◽  
Functional Studies ◽  
Quantum Chemical Model ◽  
Polycyclic Aromatic ◽  
Hydrogenation Reactions ◽  
No Activation

Density functional studies show that neutral HnPAHs are able to catalyze the formation of water with no activation barrier.

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