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The photophysical and electrochemical properties of a fumaramide rotaxane stoppered with C(60) are reported. The results evidenced the strong binding interactions between the template and the macrocycle, which are also supported by molecular modelling.

We report on the singlet ground and singlet/triplet excited-state features of a series of bucky ferrocenes, bucky ruthenocenes, and respective reference compounds. In the bucky ferrocene conjugates, intimate contacts between the fullerenes and ferrocenes result in appreciable ground-state interactions-suggesting a substantial shift of charge density from the electron donor (i.e., ferrocene) to the electron acceptor (i.e., fullerene). In contrast, no prominent charge-transfer features were observed for the bucky ruthenocene conjugates. An arsenal of experimental techniques, ranging from fluorescence (i.e., steady state and time-resolved) and pump probe experiments (i.e., femtosecond and nanoseconds) to pulse radiolysis, were employed to examine excited-state interactions. In the excited states, bucky ferrocene conjugates are dominated by rapid charge separation reactions (0.8 +/- 0.1 ps) to yield metastable radical ion pairs. The radical ion pair lifetimes vary between 27 and 39 ps. No charge separation was, however, found in the corresponding bucky ruthenocence. Instead, an intrinsically faster excited-state deactivation (approximately 200 ps) evolves from the heavier ruthenium center-relative to iron. This effect is further augmented by the unfavorably shifted oxidation potential in ruthenocene of about 0.61 V, which in ruthenocene (-deltaG(ET) = -0.26 eV), in contrast to ferrocene (-deltaG(ET) = 0.35 eV), renders charge separation thermodynamically unfeasible.

Light-harvesting C(60)-based dyads endowed with a truxene fluorophore unit have been synthesized. Their photophysical studies in solution reveal a singlet-singlet energy transfer deactivation mechanism that confirms the actuation of the latter as an efficient molecular panel for light absorption and energy transduction. Those processes strongly depend on the nature of the linker connecting both chromophores, such as C(60) and truxene, owing to the overlapping degree between their respective orbitals. [structure: see text]

A new metallofullerene, La2@C78, has been synthesized by DC arc discharge method, isolated by high-performance liquid chromatography, and characterized by laser desorption time-of-flight mass spectrometry, UV-vis-NIR absorption, differential pulse voltammetry, 13C NMR spectroscopy, and theoretical calculations. The La2@C78/CS2 solution is dark violet and presents several characteristic absorption features at 647, 561, 533, and 386 nm, with an onset around 1000 nm. With respect to empty D3-C78, the capability of La2@C78 as an electron acceptor or donor is stronger. Addition of 1,1,2,2-tetrakis(2,4,6-trimethylphenyl)-1,2-disirane to La2@C78 photochemically, as well as thermally, affords bis- and mono-adducts. Theoretical studies and 13C NMR spectroscopic analysis of La2@C78 indicate that it possesses a D3h-C78 cage (78:5).