title: Electrochemical synthesis and characterisation of alternating tripyridyl-dipyrrole molecular strands with multiple nitrogen-based donor-acceptor binding sites.
abstract: Synthesis of alternating pyridine-pyrrole molecular strands composed of two electron-rich pyrrole units (donors) sandwiched between three pyridinic cores (acceptors) is described. The envisioned strategy was a smooth electrosynthesis process involving ring contraction of corresponding tripyridyl-dipyridazine precursors. 2,6-Bis[6-(pyridazin-3-yl)]pyridine ligands 2a-c bearing pyridine residues at the terminal positions were prepared in suitable quantities by a Negishi metal cross-coupling procedure. The yields of heterocyclic coupling between 2-pyridyl zinc bromide reagents 12a-c and 2,6-bis(6-trifluoromethanesulfonylpyridazin-3-yl)pyridine increased from 68 to 95% following introduction of electron-donating methyl groups on the metallated halogenopyridine units. Favorable conditions for preparative electrochemical reduction of tripyridyl-dipyridazines 2b,c were established in THF/acetate buffer (pH 4.6)/acetonitrile to give the targeted 2,6-bis[5-(pyridin-2-yl)pyrrol-2-yl]pyridines 1b and 1c in good yields. The absorption behavior of the donor-acceptor tripyridyl-dipyrrole ligands was evaluated and compared to theoretical calculations. Highly fluorescent properties of these chromophores were found (ν(em)≈2 × 10(4) cm(-1) in MeOH and CH(2)Cl(2)), and both pyrrolic ligands exhibit a remarkable quantum yield in CH(2)Cl(2) (φ(f)=0.10). Structural studies in the solid state established the preferred cis conformation of the dipyrrolic ligands, which adopting a planar arrangement with an embedded molecule of water having a complexation energy exceeding 10 kcal mol(-1). The ability of the tripyridyl-dipyrrole to complex two copper(II) ions in a pentacoordinate square was investigated.
authors.affiliation: Laboratoire de Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR 6230, Université de Nantes, UFR des Sciences et des Techniques, 2, rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Tabatchnik-Rebillon
authors.forename: Christophe
authors.initials: C
authors.lastname: Aubé
authors.forename: Hicham
authors.initials: H
authors.lastname: Bakkali
authors.forename: Thierry
authors.initials: T
authors.lastname: Delaunay
authors.forename: Gabriel Thia
authors.initials: GT
authors.lastname: Manh
authors.forename: Virginie
authors.initials: V
authors.lastname: Blot
authors.forename: Christine
authors.initials: C
authors.lastname: Thobie-Gautier
authors.forename: Eric
authors.initials: E
authors.lastname: Renault
authors.forename: Marine
authors.initials: M
authors.lastname: Soulard
authors.forename: Aurélien
authors.initials: A
authors.lastname: Planchat
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Le Questel
authors.forename: Rémy
authors.initials: R
authors.lastname: Le Guével
authors.forename: Christiane
authors.initials: C
authors.lastname: Guguen-Guillouzo
authors.forename: Brice
authors.initials: B
authors.lastname: Kauffmann
authors.forename: Yann
authors.initials: Y
authors.lastname: Ferrand
authors.forename: Ivan
authors.initials: I
authors.lastname: Huc
authors.forename: Karène
authors.initials: K
authors.lastname: Urgin
authors.forename: Sylvie
authors.initials: S
authors.lastname: Condon
authors.forename: Eric
authors.initials: E
authors.lastname: Léonel
authors.forename: Michel
authors.initials: M
authors.lastname: Evain
authors.forename: Jacques
authors.initials: J
authors.lastname: Lebreton
authors.forename: Denis
authors.initials: D
authors.lastname: Jacquemin
authors.forename: Muriel
authors.initials: M
authors.lastname: Pipelier
authors.forename: Didier
authors.initials: D
authors.lastname: Dubreuil
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D002384:Catalysis; D049109:Cell Proliferation / Q000187:drug effects; D003300:Copper / Q000737:chemistry*; D004354:Drug Screening Assays, Antitumor; D055664:Electrochemical Techniques; D005260:Female; D006801:Humans; D008024:Ligands; D008297:Male; D008956:Models, Chemical; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D008024:Ligands; D011725:Pyridines; D011758:Pyrroles; D003300:Copper; D009584:Nitrogen