Acenaphto[1,2-k]fluoranthene: Role of the Carbon Framework Transformation for Tuning Electronic Properties

Acenaphtho[1,2- k ]fluoranthene ( 1 ) is synthesized via tandem cyclization during the dehydrofluorination of 1,4-di(1-naphthyl)-2,5-difluorobenzene ( 2 ) on activated γ-Al 2 O 3 . Presence of residual hydroxyl groups in alumina reduce the yield of target product 1 because of the side hydrolysis of fluoroarenes with the formation a product of partial cyclization, 9-(1-naphthyl)fluoranthen-8-ol ( 1b ). The formation of negative ions (NI) of compounds 1 and 2 in the gas phase is studied by means of dissociative electron attachment (DEA) spectroscopy. Long-lived molecular NIs 1 and 2 are registered at the thermal energies of electrons, and patterns of their fragmentation are established. The adiabatic electron affinities of compounds 1 and 2 are estimated in the Arrhenius approximation and equal 1.17 ± 0.12 and 0.71 ± 0.07 eV, respectively, which agree with data from quantum chemical modeling at the level of the density functional theory (DFT). Electronic transitions for compounds 1 and 2 are studied via optical absorption and fluorescence spectroscopy. Fluorescence quantum yields are measured, and the resulting data are interpreted according to the time dependent DFT. The electrochemical properties of compounds 1 , 1b , and 2 are studied via cyclic voltamperometry, and the levels of boundary molecular orbitals are estimated on the basis of their formal potentials of reduction and oxidation.