The Intra-annular Internal Heavy-atom Effect on the Fluorescence and Phosphorescence Properties of Oxygen, Sulphur or Selenium Containing Heterocyclic Systems Related to Dibenzo [b,n] perylene
Fluorescence and phosphorescence properties of dibenzo [2,3:10,11] perylo [1,12-bcd] furan (1), dibenzo [2,3:10,11] perylo [1,12-bcd] thiophene (2), and dibenzo [2,3:10,11 ] perylo [1,12-bcd] selenophene (3) have been studied. Fluorescence quantum yields as well as phosphorescence lifetimes correlate linearly with where ck are the Hückel AO coefficients in the HOMO of the parent carbocyclic system dibenzo [b, n] perylene (4) on carbon centres k to which the hetero-atom is bound, and ζ is the spin-orbit coupling constant of the heavy-atom present. The half-value concentration of fluorescence quenching (quencher: methyl iodide) of 1 - 3 increases with increasing strength of the internal heavy-atom effect present