scholarly journals Excited States Symmetry Breaking and In-Plane Polarization Cause Chiral Reversal in Diastereomers

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4680
Author(s):  
Chenglong Wang ◽  
Jingang Wang ◽  
Chunyang Wang
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Symmetry Breaking ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Physical Mechanism ◽  
Electromagnetic Interaction ◽  
Electronic Transitions ◽  
Conjugated Systems ◽  
Polycyclic Aromatic

In this work, we investigate the electronic transitions and chirality of three isomers of huge conjugated systems: asymmetric diastereomers (MMMM) and two symmetrical diastereomers (PMPM and PPMM). The physical mechanism of flipping has been studied theoretically. The new ribbon-shaped polycyclic aromatic hydrocarbons (PAHs) molecule is formed by connecting three graphene-like systems with large conjugated π orbitals. By calculating and analyzing electromagnetic interaction decomposition over distance, it can be found that the chirality reversal of different energies is caused by the symmetrical fracture of TMDM in the Z direction. The chirality reversal at the same energy is caused by the in-plane polarization of the TMDM along the Y direction.

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.

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.

Electronically excited states of PANH anions

2015 ◽  
Vol 17 (22) ◽  
pp. 14761-14772 ◽  
Author(s):  
Mallory L. Theis ◽  
Alessandra Candian ◽  
Alexander G. G. M. Tielens ◽  
Timothy J. Lee ◽  
Ryan C. Fortenberry
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Electronically Excited States ◽  
Electronically Excited ◽  
Polycyclic Aromatic ◽  
Derivatives Of

The singly deprotonated anion derivatives of nitrogenated polycyclic aromatic hydrocarbons are shown likely to possess dipole-bound and even valence excited states for the larger systems.

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.

Exploration of Kobayashi’s aryne precursor: A potent reactive platform for the synthesis of polycyclic aromatic hydrocarbons

2020 ◽  
Author(s):  
Manashi Sarmah ◽  
Abhilash Sharma ◽  
Pranjal Gogoi
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Conjugated Systems ◽  
Transient Nature ◽  
Polycyclic Aromatic

The transient nature of arynes encompasses a remarkable passage in the synthetic world. Apparently, researchers have focused on construction of simple to complex π-conjugated systems using aryne as the reactive...

Electron delocalization and electron density of small polycyclic aromatic hydrocarbons in singlet excited states

2016 ◽  
Vol 18 (17) ◽  
pp. 11792-11799 ◽  
Author(s):  
Mar Estévez-Fregoso ◽  
Jesús Hernández-Trujillo
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Electron Density ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Electron Delocalization ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Electron delocalization allows us to study the similarity and aromaticity of PAHs in excited states, and can be correlated with the excitation energies.

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