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Final Activity Report Summary - FDPA (Fullerene Derivatives For Photonic Applications: Design, Synthesis and Measurements)

Linear scaling techniques, O(N), have been extensively used for the computation of the L&NLO properties of a series of fullerene derivatives. Several improvements and extensions have been implemented and checked. A general reduced dimensionality finite field nuclear relaxation method for calculating vibrational NLO properties of molecules with large contributions due to anharmonic motions has been introduced. Using a wide variety of quantum-chemical methods we have analysed in detail the linear and non-linear optical properties of [60]fullerene-chromophore dyads of different electron-donor character. The dyads are composed of [60]fullerene covalently linked with 2,1,3-benzothiadiazole and carbazole derivatives. Linear scaling calculations of molecular (hyper)polarisabilities were performed using wave function theory as well as density functional theory (DFT). For [60]fullerene-chromophore dyads we have, additionally, observed that the double harmonic vibrational contribution to the static first hyperpolarisability is much larger than its electronic counterpart.

A nuclear relaxation treatment of vibrational anharmonicity for a model fulleropyrrolidine molecule yields a first-order contribution that is substantially more important than the double harmonic term for the static first hyperpolarisability . Electronic and vibrational nuclear relaxation (NR) contributions to the dipole (hyper)polarisabilities of the endohedral fullerene Li@C60 and its monovalent cation [Li@C60]+ are calculated. Many results are new, while others differ significantly from those reported previously using more approximate methods. Whereas the NR contribution to the static linear polarisabilities is small in comparison with the corresponding electronic property, the opposite is true for the static hyperpolarisabilities.

The dipole moment and the (hyper)polarisabilities of C28 and Ti@C28 have been computed. The electronic and vibrational contributions are presented. We reported on the linear and nonlinear optical properties of C60-triphenylamine (TPhA) hybrids. The synthesised materials were prepared following the 1,3-dipolar cycloaddition of azomethine ylides onto the skeleton of C60 forming the TPhA-based monoadduct, equatorial bis-adduct and dumbell C60.

We have found that the total second-order hyperpolarisability of the C60-TphA-C60 system is several times larger than that of TPhA-C60. The results of experimental measurements are supported by quantum-chemical calculations. Endohedral fullerenes Gd@C82, as well as some di-Lu-based metallofullerenes, were produced. A coumarin derivative with a malonate unit has been synthesised and used for the preparation of a fullerene-coumarin dyad through the Bingel cyclopropanation method. Our studies clearly show the presence of electronic interactions between C60 and modified coumarin in the ground state; efficient electron-transfer quenching of the singlet excited state of the coumarin moiety by the appended fullerene sphere was also observed.

The redox potentials of the C60-coumarin dyad were determined and the energetics of the electron-transfer processes were evaluated. Isophthaloyl-bridged porphyrin dimer (IBP) forms a 1:1 complex with La@C82. Despite the photoactive character of the porphyrin moiety, the association ability of IBP for La@C82 is based exclusively on cooperative supramolecular forces, namely structural non-covalent interactions of the porphyrin rings as well as of the nitrogen atoms present in 1 with La@C82. The host-guest interaction between single-wall carbon nanotubes and azafullerenes encapsulated in them has been investigated by UV-vis-NIR absorption and photoluminescence spectroscopy. The interaction between SWCNTs and the encapsulated azafullerenes has been explained by weak intermolecular forces.

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