Energy Transfer between CNT Surface and -Re(CO)₃(phen)⁺∗ Pendants Grafted to P4VP in Nanohybrid Shish-Kebob-like Structures

The adsorption of a Re(CO)₃(phen)-poly(4-vinylpyridine) polymer, RePVP, on multiwall carbon nanotubes surfaces is studied by transmission electron microscopy and absorption spectroscopy in combination with chemometric techniques in MeOH/H₂O solvent mixture. Nanohybrid structures like a shish-kebab (NHSK) are observed by TEM when RePVP is wrapped around carbon nanotubes (CNTs) surfaces. The association between RePVP and CNTs studied by absorption spectroscopy suggests the coexistence of CNTs with a high or low content of adsorbed RePVP on their surface. In the absence of CNTs, the photophysical properties of RePVP (i.e., luminescence quantum yield, φ_L, and amplitude-weighted average lifetimes, «τ») are strongly dependent on the morphology of the polymer as witnessed by the dependence of φ_L on the concentration of RePVP (C_RePVP) and the fact that in CH₃CN φ_L and «τ»are sensitive to O₂ while in a MeOH/H₂O solvent mixture they are not. In the NHSK, an energy-transfer process between excited -[Re(CO)₃(phen)]⁺∗ pendent chromophores and the CNTs surface, with static and dynamic components, is responsible for the quenching of the RePVP luminescence by CNTs.