title: Synthesis and charge-transfer chemistry of La2@I(h)-C80/Sc3N@I(h)-C80-zinc porphyrin conjugates: impact of endohedral cluster.
abstract: Two stable electron donor-acceptor conjugates, that is, 3 and 5b, employing La(2)@I(h)-C(80) and Sc(3)N@I(h)-C(80), on one hand, and zinc tetraphenylporphyrin, on the other hand, have been prepared via [1+2] cycloaddition reactions of a diazo precursor. Combined studies of crystallography and NMR suggest a common (6,6)-open addition pattern of 3 and 5b. Still, subtly different conformations, that is, a restricted and a comparatively more flexible topography, emerge for 3 and 5b, respectively. In line with this aforementioned difference are the electrochemical assays, which imply appreciably stronger I(h)-C(80)/ZnP interactions in 3 when compared to those in 5b. Density functional calculations reveal significant attractions between the two entities of these conjugates, as well as their separately localized HOMOs and LUMOs. The geometrical conformations and LUMO distributions of 3 and 5b, at our applied computational level, are slightly varied with their different endohedral clusters. The clusters also exert different impact on the excited state reactivity of the conjugates. For example, 3 undergoes, upon photoexcitation, a fast charge separation process and yields a radical ion pair, whose nature, namely, (La(2)@C(80))(•-)-(ZnP)(•+)) versus (La(2)@C(80))(•+)-(ZnP)(•-)), varies with solvent polarity. 5b, on the other hand, afforded the same (Sc(3)N@C(80))(•-)-(ZnP)(•+)) radical ion pair regardless of the solvent.
authors.affiliation: Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan.
authors.forename: Lai
authors.initials: L
authors.lastname: Feng
authors.forename: Shankara Gayathri
authors.initials: SG
authors.lastname: Radhakrishnan
authors.forename: Naomi
authors.initials: N
authors.lastname: Mizorogi
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Slanina
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Nikawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akasaka
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase
authors.forename: Nazario
authors.initials: N
authors.lastname: Martín
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Guldi
mesh_terms: D004563:Electrochemistry; D007811:Lanthanum / Q000737:chemistry*; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry
chemical_list: D008665:Metalloporphyrins; D012997:Solvents; C048955:zinc tetraphenylporphyrin; D007811:Lanthanum