title: Cyclic 2,12-porphyrinylene nanorings as a porphyrin analogue of cycloparaphenylenes.
abstract: β-to-β Directly linked cyclic Ni(II) porphyrin trimer, tetramer, and pentamer ([3]CP, [4]CP, and [5]CP) have been synthesized by reaction of a 2,12-diborylated Ni(II) porphyrin with Pt(cod)Cl2 followed by reductive elimination. The structures of these cyclic porphyrin arrays have been revealed by X-ray diffraction analysis. The strain energies of these cyclic oligomers are calculated to be 77, 57, and 47 kcal/mol for [3]CP, [4]CP, and [5]CP, respectively. Intramolecular excitation energy hopping was observed between the (3)(d,d) states of the Ni(II) porphyrins with rates of 3.0, 4.4, and 4.6 ps for [3]CP, [4]CP, and [5]CP, respectively, reflecting the close proximity of the Ni(II) centers.
authors: Department of Chemistry, Graduate School of Science, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
authors: Hua-Wei
authors: HW
authors: Jiang
authors: Takayuki
authors: T
authors: Tanaka
authors: Hirotaka
authors: H
authors: Mori
authors: Kyu Hyung
authors: KH
authors: Park
authors: Dongho
authors: D
authors: Kim
authors: Atsuhiro
authors: A
authors: Osuka