title: Noncovalent synthesis in aqueous solution and spectroscopic characterization of multi-porphyrin complexes.
abstract: The interactions of the tetracationic meso-tetrakis(N-methyl-4-pyridyl)porphyrin (H(2)TMPyP) and its metallo derivatives (MTMPyP) (where M=copper(II), zinc(II), and gold(III) with the octa-anionic form (at neutral pH) of 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene (C(4)TsTc) lead to a series of complex species whose stoichiometry and porphyrin sequence can be easily tuned. Crystallographic, spectroscopic, and diffusion NMR studies converge towards a common picture in which a central 1:4 porphyrin/calixarene unit serves as a template for the formation of more complex species. These species arise by successive, stepwise addition of single porphyrin molecules above and below the plane of the 1:4 central core to ultimately give a 7:4 complex. Noticeably, the stoichiometry of the various complex species corresponds to the actual concentration ratio of porphyrins and calixarenes in solution allowing the stoichiometry of these species to be easily tuned. This behavior and the remarkable stability of these species allow homo-porphyrin and hetero-(metallo)porphyrin species to be formed with control of not only the stoichiometry but also the sequence of the porphyrin array. The flexibility and ease of this approach permit, in principle, the design and synthesis of porphyrin arrays for predetermined purposes. For example, we have shown that it is very easy to design and obtain mixed porphyrin species in which a foreseen photoinduced electron-transfer is indeed observed.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, 95125 Catania, Italy.
authors.forename: Fabio G
authors.initials: FG
authors.lastname: Gulino
authors.forename: Rosaria
authors.initials: R
authors.lastname: Lauceri
authors.forename: Limor
authors.initials: L
authors.lastname: Frish
authors.forename: Tamar
authors.initials: T
authors.lastname: Evan-Salem
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen
authors.forename: Rita
authors.initials: R
authors.lastname: De Zorzi
authors.forename: Silvano
authors.initials: S
authors.lastname: Geremia
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Costanzo
authors.forename: Lucio
authors.initials: L
authors.lastname: Randaccio
authors.forename: Domenico
authors.initials: D
authors.lastname: Sciotto
authors.forename: Roberto
authors.initials: R
authors.lastname: Purrello
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D017666:Deuterium Oxide / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D012995:Solubility; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
chemical_list: D011166:Porphyrins; D014867:Water; D047250:Calixarenes; C021096:tetra(4-N-methylpyridyl)porphine; D017666:Deuterium Oxide