Monomeric Azaheterofullerene Derivatives RC 59 N: Influence of the R Moiety on Spectroscopic and Photophysical Properties

We have synthesised nine monomeric azaheterofullerene (AZA) derivatives, RC 59 N, with a wide variety of different side chains R and investigated their spectroscopic and photophysical properties in toluene and o ‐dichlorobenzene (ODCB). Measurements include their ground‐state absorption spectra, molar absorption coefficient ( ε G ), fluorescence spectra, fluorescence quantum yields ( Φ F ), singlet‐state lifetimes ( τ F ), triplet‐state absorption spectra, triplet molar absorption coefficients ( ε T ), singlet oxygen ( Φ Δ ), and triplet state ( Φ T ) quantum yields. The replacement of a carbon by a nitrogen atom in the C 60 sphere strongly affects most of the spectroscopic and photophysical properties. The chemical nature of the R moiety has definite effects on these properties in contrast with minor effects on the chemical nature of the addends in [6,6]‐ring bridged monoadduct methano[60]fullerene derivatives. These effects concern properties of the ground state, singlet excited state, and triplet states of our nine RC 59 N derivatives and in particular the values of photophysical parameters ε G , ε T , Φ Δ , and Φ T , which are significantly lower than those of analogous monoadduct [6,6]‐ring bridged methano[60]fullerene derivatives.