title: [2]Catenanes decorated with porphyrin and [60]fullerene groups: design, convergent synthesis, and photoinduced processes.
abstract: A new class of [2]catenanes containing zinc(II)-porphyrin (ZnP) and/or [60]fullerene (C(60)) as appended groups has been prepared. A complete description of the convergent synthetic approach based on Cu(I) template methodology and "click" 1,3-dipolar cycloaddition chemistry is described. This new electron donor-acceptor catenane family has been subjected to extensive spectroscopic, computational, electrochemical and photophysical studies. (1)H NMR spectroscopy and computational analysis have revealed that the ZnP-C(60)-[2]catenane adopts an extended conformation with the chromophores as far as possible from each other. A detailed photophysical investigation has revealed that upon irradiation the ZnP singlet excited state initially transfers energy to the (phenanthroline)(2)-Cu(I) complex core, producing a metal-to-ligand charge transfer (MLCT) excited state, which in turn transfers an electron to the C(60) group, generating the ZnP-[Cu(phen)(2)](2+)-C(60)(*-) charge-separated state. A further charge shift from the [Cu(phen)(2)](2+) complex to the ZnP subunit, competitive with decay to the ground state, leads to the isoenergetic long distance ZnP(*+)-[Cu(phen)(2)](+)-C(60)(*-) charge-separated radical pair state, which slowly decays back to the ground state on the microsecond time scale. The slow rate of back-electron transfer indicates that in this interlocked system, as in previously studied covalently linked ZnP-C(60) hybrid materials, this process occurs in the Marcus-inverted region.
authors.affiliation: Department of Chemistry, New York University, New York, New York 10003, USA. jackson.megiatto@nyu.edu
authors.forename: Jackson D
authors.initials: JD
authors.lastname: Megiatto
authors.forename: David I
authors.initials: DI
authors.lastname: Schuster
authors.forename: Silke
authors.initials: S
authors.lastname: Abwandner
authors.forename: Gustavo
authors.initials: G
authors.lastname: de Miguel
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Guldi
mesh_terms: D000042:Absorption; D000480:Alkynes / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002384:Catalysis; D043863:Catenanes / Q000138:chemical synthesis* / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D015195:Drug Design; D004563:Electrochemistry; D004735:Energy Transfer; D037741:Fullerenes / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000480:Alkynes; D001386:Azides; D043863:Catenanes; D037741:Fullerenes; D008665:Metalloporphyrins; D011166:Porphyrins; C017802:zinc hematoporphyrin; D003300:Copper; C069837:fullerene C60