title: Xanthene-bridged cofacial bisporphyrins.
abstract: The synthesis and characterization of cofacial bisporphyrins juxtaposed by xanthene-bridged pillars are presented. The one-pot preparation of the xanthene dialdehyde avoids the lengthy bridge synthesis accompanying other cofacial porphyrin systems, thus allowing for the facile preparation of homobimetallic zinc (10), copper (11), and nickel (12) complexes. The cofacial orientation of the two porphyrin macrocycles was confirmed by X-ray crystallography. Structural data are provided for bisporphyrins 10-12: 10 (C79H82N8OZn2), triclinic, space group P1, a = 11.2671(2) A, b = 14.9809(2) A, c = 20.4852(2) A, alpha = 101.6680(10) degrees, beta = 100.8890(10) degrees, gamma = 101.8060(10) degrees, Z = 2; 11 (C79H82N8OCu2), triclinic, space group P1, a = 11.21410(10) A, b = 14.9539(5) A, c = 20.6915(7) A, alpha = 101.810(2) degrees, beta = 101.044(2) degrees, gamma = 101.722(2) degrees, Z = 2; 12 (C79H82N8ONi2), monoclinic, space group C2/c, a = 24.1671(4) A, b = 10.669 A, c = 50.5080(9) A, beta = 99.553(2) degrees, Z = 8. Exciton interactions between the porphyrin rings are apparent in electronic spectra, consistent with the cofacial superstructure. The combination of structural and spectroscopic data provides a basis for the design of additional metal derivatives for the activation of dioxygen and other small molecules.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Chang
authors.forename: Y
authors.initials: Y
authors.lastname: Deng
authors.forename: A F
authors.initials: AF
authors.lastname: Heyduk
authors.forename: C K
authors.initials: CK
authors.lastname: Chang
authors.forename: D G
authors.initials: DG
authors.lastname: Nocera
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry; D014966:Xanthenes / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
chemical_list: D001952:Bridged-Ring Compounds; D008665:Metalloporphyrins; D014966:Xanthenes; D003300:Copper; D009532:Nickel; D015032:Zinc