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Updated: Jan 6, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Electron-Hole Correlation as Unambiguous and Universal Classification for the Nature of Low-Lying ππ* States of
Marvin Hoffmann1, Stefanie A Mewes2, Sonja Wieland1
1Interdisciplinary Center for Scientific Computing , Ruprecht-Karls University , Im Neuenheimer Feld 205A , D-69120 Heidelberg , Germany.
Abstract:
The 1L and 1L classification of electronically excited states of cata-condensed hydrocarbons proposed by Platt in 1949 ( Platt , J. R. J. Chem. Phys. 1949 , 17 , 484 ) is challenged by investigating a series of N-heteronaphthalenes and comparison of their low-lying ππ* excited states to those of naphthalene. The breakdown of Platt's classification scheme for N-heterocycles is highlighted, and a reliable and versatile alternative using exciton analyses is presented. The strength of electron-hole correlation turns out to be the most reliable distinguishing feature, and thus, an alternative nomenclature of 1Lw (weakly correlated) and 1Ls (strongly correlated) is proposed. Furthermore, fundamental guidelines for their property modulation through N-atom substitution patterns are discussed.
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