Bipyridinophane‐containing conjugated polymers modulated with an intramolecular aromatic CH/π interaction

Abstract

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

PWA/silica doped sulfonated poly(ether sulfone) composite membranes for direct methanol fuel cells

“…This extraction of HPA would lead to a decrease in proton conductivity and durable lifetime in fuel cell systems. 12 Thus the retention of HPA was considered as one of the key parameters on determining the feasibility of the composite membranes used in the fuel cell systems.…”

“…11 Heteropolyacid (HPA), such as phosphotungstic acid (PWA), is one of the attractive inorganic additives because of their high proton conductivity and thermal stability in crystalline form. 12,13 Fenton and coworkers 14 recast the Nafion/HPA composite for H 2 /O 2 fuel cell and found that the HPA could increase the conductivity of the membrane. Staiti et al 15 and Shao et al 16 evaluated PWA-doped composite silica/Nafion/PWA membranes for hightemperature DMFCs (145 C).…”

Conducting Polymers as Artificial Receptors in Chemical Sensors

“…The influence of transition metals on the fluorescence of polymers 7a and 7b, which contain bipyridinophane units, has been investigated in THF solution [165]. The fluorescence of both polymers was quenched by Cu 2 þ , Co 2 þ , and Ni 2 þ ions.…”

Synthesis and characterization of high‐performance polyimides based on 6,4′‐diamino‐2‐phenylbenzimidazole

“…Recently, polyimides containing benzimidazole moieties were prepared by two-step procedure using 6,4 0 -diamino-2phenylbenzimidazole (BIA) as a monomer, resulting in good mechanical properties. 19 In this work, we developed a new synthesis route to produce the diamine monomer containing benzimidazole units, BIA. It was easily synthesized via formation of imidazole ring in NMP.…”

“…As a comparison, the synthesis of BIA was very complicated via amidation and ring formation, reported in the past. 19,20 Based on BIA, a series of polyimides were prepared by the reaction of diamine with various dehydrates using a traditional two-step procedure. Tough and flexible polyimide films with good thermal stability and mechanical properties were expected to obtain by introducing benzimidazole units into the main chains of polyimides.…”