title: Lanthanide(III) bis(phthalocyaninato)-[60]fullerene dyads: synthesis, characterization, and photophysical properties.
abstract: A novel series of double-decker lanthanide(III) bis(phthalocyaninato)-C(60) dyads [Ln(III)(Pc)(Pc')]-C(60) (M=Sm, Eu, Lu; Pc=phthalocyanine) (1 a-c) have been synthesized from unsymmetrically functionalized heteroleptic sandwich complexes [Ln(III)(Pc)(Pc')] (Ln=Sm, Eu, Lu) 3 a-c and fulleropyrrolidine carboxylic acid 2. The sandwich complexes 3 a-c were obtained by means of a stepwise procedure from unsymmetrically substituted free-base phthalocyanine 5, which was first transformed into the monophthalocyaninato intermediate [Ln(III)(acac)(Pc)] and further reacted with 1,2-dicyanobenzene in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). (1)H NMR spectra of the bis(phthalocyaninato) complexes 3 a-c and dyads 1 a-c were obtained by adding hydrazine hydrate to solutions of the complexes in [D(7)]DMF, a treatment that converts the free radical double-deckers into the protonated species, that is, [Ln(III)(Pc)(Pc')H] and [Ln(III)(Pc)(Pc')H]-C(60). The electronic absorption spectra of 3 a-c and 1 a-c in THF exhibit typical transitions of free-radical sandwich complexes. In the case of dyads 1 a-c, the spectra display the absorption bands of both constituents, but no evidence of ground-state interactions could be appreciated. When the UV/Vis spectra of 3 a-c and 1 a-c were recorded in DMF, typical features of the reduced forms were observed. Cyclic voltammetry studies for 3 a-c and 1 a-c were performed in THF. The electrochemical behavior of dyads 1 a-c is almost the exact sum of the behavior of the components, namely the double-decker [Ln(III)(Pc)(Pc')] and the C(60) fullerene, thus confirming the lack of ground-state interactions between the electroactive units. Photophysical studies on dyads 1 a-c indicate that only after irradiation at 387 nm, which excites both C(60) and [Ln(III)(Pc)(Pc')] components, a photoinduced electron transfer from the [Ln(III)(Pc)(Pc')] to C(60) occurs.
authors.affiliation: Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Ballesteros
authors.forename: Gema
authors.initials: G
authors.lastname: de la Torre
authors.forename: Axel
authors.initials: A
authors.lastname: Shearer
authors.forename: Anita
authors.initials: A
authors.lastname: Hausmann
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Herranz
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Guldi
authors.forename: Tomás
authors.initials: T
authors.lastname: Torres
mesh_terms: D037741:Fullerenes / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D054833:Isoindoles; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D012996:Solutions; D013237:Stereoisomerism
chemical_list: D037741:Fullerenes; D007211:Indoles; D054833:Isoindoles; D028581:Lanthanoid Series Elements; D012996:Solutions; C069837:fullerene C60; C013647:phthalocyanine