Synthesis and spectroscopic studies of transition-metal fullerene supramolecular systems

Synthesis and Preliminary Characterization of a PPE-Type Polymer Containing Substituted Fullerenes and Transition Metal Ligation Sites

“…Absorption spectra of precursor 2 and polymers 5-7 in 2-MTHF at optically dilute concentrations are shown in Figure 1. For the fullerenecontaining precursor, the spectrum is very similar to previously reported substituted fullerene 1 [4,6] with intense absorption bands below 350 nm typically associated with aromatic , * transitions [1,[46][47][48][49][50]. We do not observe the longer wavelength features typically associated with fullerenes, likely due to the intense absorption associated with the aromatic "hub" structure.…”

“…These changes are particularly apparent in polymer 5 that contains the fullerene and benzene moieties. The effect is less pronounced in polymer 6 that contains fullerene and bipyridine moieties due to the potential of the bipyridine to twist (vide infra), but the spectra are consistent with our small molecule studies [6] that indicated the large absorption cross section of the fullerene dominates the excitation profile of the system. Only the higher energy aromatic absorption is retained in polymer 7, which is similar to previously reported systems [51].…”

“…Previously, we observed 425 nm emission lifetimes for 1 and 1-bipyridine dyads around 150 ns that slightly decreased to ca. 100 ns upon cooling [6]. Instead, a significantly shorter lifetime is observed for these samples at room temperature.…”

“…In a 100 mL Schlenk flask 9 (0.0145 g, 0.0558 mmol), 1 [4,6] (0.0423 g, 0.0468 mmol), PdCl 2 (PPh 3 ) 2 (0.008 g, 0.0114 mmol), and CuI (0.065 g, 0.3413 mmol) were added along with a stir bar. A condenser was added, and the apparatus was purged and filled with argon.…”

“…Our focus has been the substituted fullerene 1 (Scheme 1) that provides a simple "handle" for attachment to other moieties [4][5][6]. Our initial efforts focused on small molecule systems incorporating well-known transition metal chromophores (e.g., -Re I (CO) 3 Cl and -Ru II (bpy) 2 2+ , where bpy is 2,2 -bipyridine) [7][8][9] that exhibited unique photophysical properties, including photoinduced charge transfer [6]. These charge transfer capabilities have been further confirmed with ab initio calculations [10].…”