Clar Goblet and Aromaticity Driven Multiradical Nanographenes

Abstract

The Clar Goblet, the first radicalb owtien anographene proposed by Erich Clar nearly 50 years ago, was recently synthesized.B owtie nanographenes present quasidegeneratem agnetic ground states, which make them so elusive as unique. At horough analysis is presented of the spin-state energetics of Clar Goblet and bowtie nanographenes by ab attery of existing andn ovel ab initio procedures ranging from density functionalt heory to complete active space Hamiltonians. With this, it wasp rovent hat p radicals of bowtie nanographenes sit on BP (Benzo[cd]Pyrene) moieties driven by their local aromaticity,apurely chemicalc oncept, which confers globals tabilityt ot he whole structure. Besides, an ovel Pauli energy densities analysis provided av isual intuitive explanation for this preference. These findings allow envisioning that analogous bowtie nanographenes with arbitrary polyradical character are not only feasible at the molecular scale but will share Clar Goblet's peculiar properties.

Tuning the Structure and Properties of N‐doped Positively Charged Polycyclic Aromatic Hydrocarbons

“…It has been shown that these formulas can be used to analyse the dominant modes of cyclic π-electron conjugation in these molecules. [45,46,64,82] The rings in which aromatic sextets are located (indicated by circles) are said to be "full" whereas the other rings are "empty". The current density in large fully benzenoids has previously been studied.…”

“…According to the Clar's aromatic sextet theory [45,46] molecules 1 – 3 are fully benzenoid hydrocarbons, and their Clar formulas are given in Supporting information (Figure S5). It has been shown that these formulas can be used to analyse the dominant modes of cyclic π‐electron conjugation in these molecules [45,46,64,82] . The rings in which aromatic sextets are located (indicated by circles) are said to be “full” whereas the other rings are “empty”.…”

Zero-energy modes in super-chiral nanographene networks of phenalenyl-tessellation molecules

“…These examples show the importance of controlling the appearance of both LZMs and DZMs using the super-zero-sum rule to determining the spin ground state and the low-energy effective spin Hamiltonian. Thus, our rule enables magnetic molecules and magnetic nanocarbon systems to be designed rather freely, having advantages compared with other attempts [33,34]. This may allow the material realization of quantum-computation-device structures.…”

Multi and Single-Reference Methods for the Analysis of Multi-State Peroxidation of Enolates

“…Broken-Symmetry DFT method (BS-DFT) [49][50][51][52] is an affordable method to describe open-shell singlets within a monodeterminantal scenario. This method, widely used for the treatment of diradical systems, 39,[53][54][55][56][57][58] introduces the breakdown of the spatial and spin symmetry in decoupled alpha and beta spin-orbital contributions. Then, the splitting of the spin contribution and the frontier orbital mixing introduces the correction of the static correlation.…”