Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract: A covalently functionalized fullerene comprising an electron donating aniline group coupled to the fullerene unit by a saturated heterocyclic bridge is shown to undergo a photoinduced intramolecular electron transfer process that causes quenching of the fluorescence of the adduct and strong decrease of triplet population in polar solvents. VIS-absorption, fluorescence and phosphorescence at 77 K, triplet-triplet absorption, time resolved fluorescence, and redox potentials of the fullerene adduct are presented. Analysis of the solvent dependence of the energetics of the intramolecular electron transfer is given and is in good agreement with the experimental results.

The bis(beta-diketone) ligands 1,3-bis(3-phenyl-3-oxopropanoyl)benzene, H(2)L(1) and 1,3-bis(3-phenyl-3-oxopropanoyl) 5-ethoxy-benzene, H(2)L(2), have been prepared for the examination of dinuclear lanthanide complex formation and investigation of their properties as sensitizers for lanthanide luminescence. The ligands bear two conjugated diketonate binding sites linked by a 1,3-phenylene spacer. The ligands bind to lanthanide(III) or yttrium(III) ions to form neutral homodimetallic triple stranded complexes [M(2)L(1)(3)] where M = Eu, Nd, Sm, Y, Gd and [M(2)L(2)(3)], where M = Eu, Nd or anionic quadruple-stranded dinuclear lanthanide units, [Eu(2)L(1)(4)](2-). The crystal structure of the free ligand H(2)L(1) has been determined and shows a twisted arrangement of the two binding sites around the 1,3-phenylene spacer. The dinuclear complexes have been isolated and fully characterized. Detailed NMR investigations of the complexes confirm the formation of a single complex species, with high symmetry; the complexes show clear proton patterns with chemical shifts of a wide range due to the lanthanide paramagnetism. Addition of Pirkle's reagent to solutions of the complexes leads to splitting of the peaks, confirming the chiral nature of the complexes. Electrospray and MALDI mass spectrometry have been used to identify complex formulation and characteristic isotope patterns for the different lanthanide complexes have been obtained. The complexes have high molar absorption coefficients (around 13 x 10(4) M(-1)cm(-1)) and display strong visible (red or pink) or NIR luminescence upon irradiation at the ligand band around 350 nm, depending on the choice of the lanthanide. Emission quantum yield experiments have been performed and the luminescence signals of the dinuclear complexes have been found to be up to 11 times more intense than the luminescence signals of the mononuclear analogues. The emission quantum yields and the luminescence lifetimes are determined to be 5% and 220 micros for [Eu(2)L(1)(3)], 0.16% and 13 micros for [Sm(2)L(1)(3)], and 0.6% and 1.5 micros for [Nd(2)L(1)(3)]. The energy level of the ligand triplet state was determined from the 77 K spectrum of [Gd(2)L(1)(3)]. The bis-diketonate ligand is shown to be an efficient sensitizer, particularly for Sm and Nd. Photophysical studies of the europium complexes at room temperature and 77 K show the presence of a thermally activated deactivation pathway, which we attribute to ligand-to-metal charge transfer (LMCT). Quenching of the luminescence from this level seems to be operational for the Eu(III) complex but not for complexes of Sm(III) and Nd(III), which exhibit long lifetimes. The quadruple-stranded europium complex has been isolated and characterized as the piperidinium salt of [Eu(2)L(1)(4)](2-). Compared with the triple-stranded Eu(III) complex in the solid state, the quadruple-stranded complex displays a more intense emission signal with a distinct emission pattern indicating the higher symmetry of the quadruple-stranded complex.

(1996). Photoinduced electron transfer to C60 across extended 3-and 11-bond hydrocarbon bridges: Creation of a long-lived charge separated state. Journal of Organic Chemistry, 61, 5055-5062. DOI: 10.1021/jo960678q General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Two new, rigid donor-bridge-C 60 (acceptor) dyads are presented. In one system (C 60 [3]TMPD) a 3-σ-bond bridge separates the fullerene from a powerful tetraalkyl-p-phenylenediamine donor; in the other (C 60 [11]DMA) the bridge comprises an extended array of 11 bonds, while the donor unit is a dimethylaniline group. Photoexcitation of the 3-bond system induces fast (k cs g 1.6 × 10 10 s -1 ) and virtually complete intramolecular charge separation, irrespective of solvent polarity. It is concluded that this charge separation occurs under nearly "optimal" conditions. Charge recombination, however, is also very fast, preventing the detection of the charge-separated state on a nanosecond time scale. For the 11-bond system, photoinduced charge separation only occurs in polar solvents, reaching k cs ) 5.5 × 10 9 s -1 in benzonitrile, which still implies a charge separation yield of ∼90%. Interestingly, charge recombination is now slowed down considerably, thereby allowing easy detection of the "giant dipolar" charge-separated state of C 60 [11]DMA with a lifetime of ca. 0.25 µs. The experimental results, together with semiempirical MO calculations, indicate that the special symmetry properties of the fullerene π-system may cause it to enter into very strong electronic coupling with the hydrocarbon bridge to allow fast photoinduced charge separation, while at the same time the electronic coupling relevant for charge recombination remains small.