Abstract
A method for the synthesis of optically pure C
60 derivatives containing one or two
d-galactose or
d-glucose units is described. It involves the synthesis of sugar–malonate derivatives followed by a cyclopropanation reaction with C
60. The solvent dependence of the photophysical properties of the methano[60]fullerene–sugar derivatives was studied using nanosecond laser flash photolysis coupled with kinetic UV–vis absorption spectroscopy and time-resolved singlet oxygen luminescence measurements. The triplet properties of these fullerenes, including transient absorption spectra, molar absorption coefficients and quantum yield for the photosensitised production of
1O
2 were determined in toluene, benzonitrile and acetonitrile solutions. The transient absorption spectral profiles are solvent independent although small differences are observed in the transient absorption maximum: 720±5
nm for toluene, 710±5
nm for benzonitrile and 700±5
nm for acetonitrile. Triplet state molar absorption coefficients (
ε
T) of C
60 derivatives vary from 9456±2090
M
−1
cm
−1, for compound
10
in toluene, and 15,272±4462
M
−1
cm
−1, for compound
6
in acetonitrile. Triplet state lifetimes (
τ
T) for methano[60]fullerene–sugar derivatives, under our experimental conditions, are similar in toluene or benzonitrile solutions (47.5±1.1
μs≤
τ
T≤51.4±2.0
μs) but are lower in acetonitrile solutions (31.8±0.6
μs≤
τ
T≤43.0±1.1
μs). Toluene and benzonitrile solutions of C
60 derivatives have
Φ
Δ close to unity.
Graphical Abstract