Dibenzotetraphenylperiflanthene: Synthesis, Photophysical Properties, and Electrogenerated Chemiluminescence

Fissure coupling of the fluoranthene adduct (7,12-diphenyl)benzo[k]fluoranthene (3) using AlCl3/NaCl, CoF3/TFA, or Tl(OCOCF3) gave the new polyaromatic hydrocarbon dibenzo{[f,f']-4,4',7,7'-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene (4). Crystal data for 4: triclinic space group P1h, a ) 10.569(2) Å, b ) 11.565(4) Å, c ) 13.001(3) Å, R ) 95.05(2)°, â ) 111.24(1)°, γ ) 100.53(1)°, Z ) 1, RF ) 0.075%. Compounds 3 and 4 are both highly fluorescent in solution and display relative fluorescence quantum yields of φF ) 1.0 and 0.85, respectively. The electrochemistry and electrogenerated chemiluminescence (ECL) of each compound has been investigated. The cyclic voltammogram of 3 in benzene-acetonitrile (9:1) shows that the compound undergoes a reversible reduction and an irreversible oxidation, whereas the cyclic voltammogram of 4 displays the reversible formation of both singly and doubly charged cations and anions. Compounds 3 and 4 undergo ECL to yield blue and orange-red light, respectively, with an ECL efficiency of ∼2% for 4. Emission from 4 is observed in the ECL of unstirred solutions of 3. This indicates that 4 is produced at the electrode during the ECL experiment, presumably via an electrochemical oxidative coupling process during the anodic potential steps.