Fig. 2. (a) The synthesis of stiff-stilbene derivatives (E)-S5 and (E)-S6 by McMurry coupling and Rieche formylation, (b) crystal structures of (E)-2, (E)-S5, and (E)-S6, (c) molecular structures of (E)-S1 to (E)-S6 and the normalized steady-state absorption spectra of (E)-S1 to (E)-S6 ((E)-S1 in DMSO and others in CH₂Cl₂, 298 K).