title: Porphyrin amino acids-amide coupling, redox and photophysical properties of bis(porphyrin) amides.
abstract: New trans-AB2C meso-substituted porphyrin amino acid esters with meso-substituents of tunable electron withdrawing power (B = mesityl, 4-C6H4F, 4-C6H4CF3, C6F5) were prepared as free amines 3a-3d, as N-acetylated derivatives Ac-3a-Ac-3d and corresponding zinc(II) complexes Zn-Ac-3a-Zn-Ac-3d. Several amide-linked bis(porphyrins) with a tunable electron density at each porphyrin site were obtained from the amino porphyrin precursors by condensation reactions (4a-4d) and mono- and bis(zinc(II)) complexes Zn(2)-4d and Zn(1)Zn(2)-4d were prepared. The electronic interaction between individual porphyrin units in bis(porphyrins) 4 is probed by electrochemical experiments (CV, EPR), electronic absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy in combination with DFT/PCM calculations on diamagnetic neutral bis(porphyrins) 4 and on respective charged mixed-valent radicals 4(+/-). The interaction via the -C6H4-NHCO-C6H4- bridge, the site of oxidation and reduction and the lowest excited singlet state S1, is tuned by the substituents on the individual porphyrins and the metalation state.
authors.affiliation: Johannes Gutenberg-University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
authors.forename: Jascha
authors.initials: J
authors.lastname: Melomedov
authors.forename: Anica
authors.initials: A
authors.lastname: Wünsche von Leupoldt
authors.forename: Michael
authors.initials: M
authors.lastname: Meister
authors.forename: Frédéric
authors.initials: F
authors.lastname: Laquai
authors.forename: Katja
authors.initials: K
authors.lastname: Heinze
mesh_terms: D000577:Amides / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D015032:Zinc / Q000737:chemistry
chemical_list: D000577:Amides; D000596:Amino Acids; D009942:Organometallic Compounds; D011166:Porphyrins; D015032:Zinc