2, 2′-, 3, 3′-, and 9, 9′-Diphenanthrylpoly-ynes (V n, VI n, and VII n, n= 1–6) were synthesized and their electronic spectra were measured. It was found that the longest- wavelength absorption maxima (λ max) in the spectra of each series of the diphenanthrylpoly-ynes (V n, VI n and VII n) shift linearly with the xth power of the number of acetylenic bond (n),[λ max∝ nx], being x= 1.3 for V n and x= 1.4 for VI n and VII n.
