The main properties of the triplet states and the yields of singlet oxygen generation for a series of methano[60]fullerene adducts with increasing numbers of substituents were determined. The triplet properties investigated are energies, triplet−triplet absorption spectra, extinction coefficients, and quantum yields. A strong correlation is observed between several triplet properties and the topology of the fullerene core. Successive fragmentation of the chromophore of the parent C60 results in higher triplet energies and lower triplet quantum yields. In addition, singlet oxygen quantum yields (φΔ) were determined for all adducts and decrease as the area of the conjugated fullerene core decreases.

We report the quantum yields for singlet oxygen production by a series of porphyrazines (pz) of the form M[pz(An;B4-n)] (Scheme 1), where the peripheral substituent A is [S-R]2 with R = (CH2CH2O)3H, B is a fused alpha,alpha'-dialkoxybenzo group and M = 2H, Mg or Zn. These compounds show intense near-IR absorbance/emission (longest wavelength emission, approximately 830 nm). Their solubilities vary with R, whereas their optical properties do not. We show that singlet oxygen sensitization by these luminescent compounds can be "tuned" from essentially off to on by varying n and selection among M = 2H, Mg or Zn. The quantum yields vary ca 60-fold within the set of compounds studied, from phidelta = 0.007 for compound 3 to phidelta = approximately 0.4 for compound 11.

In this report we examine the photophysical properties of two novel C60 derivatives. These compounds consist of a ring-opened C60 derivative (2) and its dihydro precursor (1), both of which include an orifice. The ground-state absorption spectra and the triplet−triplet absorption spectra were recorded for both derivatives. Extinction coefficients for the ground-state absorption (ε) and the triplet excited state (ΔεT - T) were calculated. The derivatives have triplet energies (E T) lower than that of C60, and the triplet quantum yields (φT) are somewhat lower than that of C60. These compounds remain good photosensitizers for the formation of singlet oxygen, with high quantum yields (φΔ). Thus, in many respects the photophysics of these buckyballs with an orifice still resemble pristine fullerenes.

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We report the quantum yields for singlet oxygen production by a series of porphyrazines (pz) of the form M[pz(An;B4−n)] (Scheme 1), where the peripheral substituent A is [S–R]2 with R = (CH2CH2O)3H, B is a fused α,α′‐dialkoxybenzo group and M = 2H, Mg or Zn. These compounds show intense near‐IR absorbance/emission (longest wavelength emission, ∼830 nm). Their solubilities vary with R, whereas their optical properties do not. We show that singlet oxygen sensitization by these luminescent compounds can be “tuned” from essentially off to on by varying n and selection among M = 2H, Mg or Zn. The quantum yields vary ca 60‐fold within the set of compounds studied, from φΔ= 0.007 for compound 3 to φΔ=∼0.4 for compound 11. Scheme 1 . (i) Mg(OPr)2, n‐PrOH at reflux, 7 h; (ii) trifluoroacetic acid (TFA), CH2Cl2, 20°C, 1 h; (iii) ZnCl2, MeOH/CH2Cl2, at reflux, 1 h