Electron affinities of polycyclic aromatic hydrocarbons by means of B3LYP/6-31+G* calculations.
The gas-phase experimental adiabatic electron affinities (AEAs) of the polycyclic aromatic hydrocarbons (PAHs) anthracene, tetracene, pentacene, chrysene, pyrene, benzo[a]pyrene, benzo[e]pyrene, and fluoranthene are well reproduced using the hybrid density functional method B3LYP with the 6-31+G* basis set, indicating that the smallest addition of diffuse functions to the basis set is suitable for a correct description of the stable PAH anion states. The calculated AEAs also give a very good linear correlation with available reduction potentials measured in solution. The AEAs (not experimentally available) of the isomeric benzo[ghi]fluoranthene and cyclopenta[cd]pyrene, commonly found in the environment, are predicted to be 0.817 and 1.108 eV, respectively, confirming the enhancement of the electron-acceptor properties associated with fusion of a peripheral cyclopenta ring. The calculated localization properties of the lowest unoccupied MO of cyclopenta[cd]pyrene, together with its relatively high electron affinity, account for a high reactivity at the ethene double bond of this PAH in reductive processes.
Modelli
Alberto
A
Dipartimento di Chimica G. Ciamician, Università di Bologna, via Selmi 2, 40126 Bologna, Italy. alberto.modeli@unibo.it
Mussoni
Laura
L
Fabbri
Daniele
D
D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D005449:Fluorenes / Q000737:chemistry; D007536:Isomerism; D015394:Molecular Structure; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry
D005449:Fluorenes; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; C016328:cyclopenta(c,d)pyrene; C022921:benzo(k)fluoranthene