Recently synthesized porphyrin-fullerene dyads with two separate linkers form a nearly symmetric complex with π-stack sandwich-like structure. The interchromophore interactions of such complexes can be finetuned by varying the linker lengths, which opens an opportunity to control physical and chemical properties of the dyads. Absorption spectroscopy emerged as a convenient means to register the interchromophore interactions: the spectra of the chromophores ground-state absorptions show appreciable perturbations and, more importantly, an additional absorption feature is discernible in the near-infrared region. Similarly, the emission spectra have a character typical for intramolecular exciplex. These new spectral features (i.e., absorption and emission) were attributed to a new electronic state, namely, an intramolecular preformed exciplex, featuring a common molecular orbital with a partial charge transfer (CT) character. From the mechanistic point of view, it is important that the preformed exciplex preceded the actual nonemitting charge separated (CS) state. The quantitative analysis of the CT absorption and the exciplex emission bands within the framework of the Marcus electron transfer (ET) theory allowed us to estimate the energy of the exciplex, ∆G°, the solvent or outer-sphere reorganization energy, λ s , the internal reorganization energy, λ V , the energy of the vibrational mode, E V , and the electronic coupling matrix element, V. Variation in the linker lengths shows that mainly the electronic coupling is affected by this structural modification, leaving the other parameters essentially unchanged. The strongest coupling, V ) 450 cm -1 (0.056 eV), was observed for the dioxyethyl type of linkers, whereas in the shorter, oxymethyl type, and longer, dioxypropyl type, dyads the couplings were much weaker (190 and 270 cm -1 , respectively). Photodynamics of the dyads was studied in the femtoand picosecond time domains, using the emission up-conversion and absorption pump-probe techniques.

The manipulation of single magnetic molecules may enable new strategies for high-density information storage and quantum-state control. However, progress in these areas depends on developing techniques for addressing individual molecules and controlling their spin. Here, we report success in making electrical contact to individual magnetic N@C(60) molecules and measuring spin excitations in their electron tunnelling spectra. We verify that the molecules remain magnetic by observing a transition as a function of magnetic field that changes the spin quantum number and also the existence of non-equilibrium tunnelling originating from low-energy excited states. From the tunnelling spectra, we identify the charge and spin states of the molecule. The measured spectra can be reproduced theoretically by accounting for the exchange interaction between the nitrogen spin and electron(s) on the C(60) cage.

Control over the interchromophore separation, their angular relationship, and the spatial overlap of their electronic clouds in several ZnP-C(60) dyads (ZnP=zinc porphyrin) is used to modulate the rates of intramolecular electron transfer. For the first time, a detailed analysis of the charge transfer absorption and emission spectra, time-dependent spectroscopic measurements, and molecular dynamics simulations prove quantitatively that the same two moieties can produce widely different electron-transfer regimes. This investigation also shows that the combination of ZnP and C(60) consistently produces charge recombination in the inverted Marcus region, with reorganization energies that are remarkably low, regardless of the solvent polarity. The time constants of electron transfer range from the mus to the ps regime, the electronic couplings from a few tens to several hundreds of cm(-1), and the reorganization energies remain below 0.54 eV and can be as low as 0.16 eV.

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