Notizen: Zur Lumineszenz von aromatischen Verbindungen mit Schweratom-Substituenten in unterschiedlichen Bindungssituationen / On the Luminescence of Aromatic Compounds with Heavy Atom Substituents in Different Bonding Situations.

Abstract

Compounds like III(4,9,10,11,12,13,13-Heptachloro-8b,9,12,12a-tetrahydro-9,12-methano-benzo[e]pyrene) are ex­amples for systems with heavy atom substituents in two different bonding situations. The halogen directly connected with the 7-electronic system causes an internal heavy atom effect whilst the halogens isolated from the .7-system by aliphatic carbons produce a “quasi external” heavy atom effect. The observation that the internal heavy atom effect in III is weaker than in halo phenanthrenes is explained with the lower electron density in the phenanthrene unit of III compared to phenanthrene. this lower electron density being a result of field and inductive effects of the peripherically arranged chlorine atoms.