Bipyridinophane-fluorene conjugated copolymers have been synthesized via Suzuki and Heck coupling reactions from 5,8-dibromo-2,11-dithia[3]paracyclo [3](4,4 0 )-2,2 0 -bipyridinophane and suitable fluorene precursors. Poly [2,7-(9,9-dihexylfluorene)-coalt-5,8-(2,11-dithia[3]paracyclo [3](4,4 0 )-2,2 0 -bipyridinophane)] (P7) exhibits large absorption and emission redshifts of 20 and 34 nm, respectively, with respect to its planar reference polymer Poly[2,7-(9,9-dihexylfluorene)-co-alt-1,4-(2,5-dimethylbenzene)] (P11), which bears the same polymer backbone as P7. These spectral shifts originate from intramolecular aromatic CÀ ÀH/p interactions, which are evidenced by ultraviolet-visible and 1 H NMR spectra as well as X-ray single-crystal structural analysis. However, the effect of the intramolecular aromatic CÀ ÀH/p interactions on the spectral shift in poly[9,9-dihexylfluorene-2,7-yleneethynylene-co-alt-5,8-(2,11-dithia[3]paracyclo[3](4,4 0 )-2,2 0 -bipyridinophane)] (P10) is much weaker. Most interestingly, the quenching behaviors of these two conjugated polymers are largely dependent on the polymer backbone. For example, the fluorescence of P7 is efficiently quenched by Cu 2þ , Co 2þ , Ni 2þ , Zn 2þ , Mn 2þ , and Ag þ ions. In contrast, only Cu 2þ , Co 2þ , and Ni 2þ ions can partially quench the fluorescence of P10, but much less efficiently than the fluorescence of P7. The static Stern-Volmer quenching constants of Cu 2þ , Co 2þ , and Ni 2þ ions toward P7 are of the order of 10 6 M À1 , being 1300, 2500, and 37,300 times larger than those of P10, respectively. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: [4154][4155][4156][4157][4158][4159][4160][4161][4162][4163][4164] 2006