title: Synthesis of nanometer-scale porphyrin wheels of variable size.
abstract: Starting from 1,3-phenylene linked diporphyrin zinc(II) complex 2ZA, repeated stepwise Ag I-promoted coupling reactions provided linear oligomers from 2nZA up to 128ZA. Of these zigzag shaped porphyrin arrays, the Ag I-promoted intramolecular cyclization reaction of 2 nZA (n=5, 6, 8, 9, 12, and 16) under dilute conditions gave the corresponding cyclic porphyrin wheels C2nZA (n=5, 6, 8, 9, 12, and 16), whereas large arrays 2nZA (n=24, 32, and 48) did not provide cyclic porphyrin products. These large discrete porphyrin arrays and wheels were fully characterized by means of 1H NMR spectroscopy, MALDI-TOF mass spectrometry, UV/Vis absorption spectroscopy, GPC-HPLC analysis, and the scanning tunneling microscopy (STM) technique. The STM images of C12ZA and C18ZA reveal their large circular structures. In the cyclic structures of C2nZA in solution, however, the gradual decrease in fluorescence quantum yields and fluorescence lifetimes are observed, reflecting some conformational heterogeneities. Collectively, the present work provides an important contribution to the construction of fully covalently linked large cyclic arranged porphyrin arrays with ample electronic interactions as a model of light-harvesting antenna.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hori
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Peng
authors.forename: Naoki
authors.initials: N
authors.lastname: Aratani
authors.forename: Akihiko
authors.initials: A
authors.lastname: Takagi
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Tomoji
authors.initials: T
authors.lastname: Kawai
authors.forename: Zin Seok
authors.initials: ZS
authors.lastname: Yoon
authors.forename: Min-Chul
authors.initials: MC
authors.lastname: Yoon
authors.forename: Jaesung
authors.initials: J
authors.lastname: Yang
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Osuka
mesh_terms: D018360:Crystallography, X-Ray; D003500:Cyclization; D047028:Macrocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D016252:Microscopy, Scanning Tunneling / Q000379:methods; D008958:Models, Molecular; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D011166:Porphyrins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013997:Time Factors; D015032:Zinc / Q000737:chemistry*
chemical_list: D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D011166:Porphyrins; D015032:Zinc