title: Design and DNA binding of an extended triple-stranded metallo-supramolecular cylinder.
abstract: A new tetracationic triple-stranded supramolecular cylinder is prepared from a bis(pyridylimine) ligand containing a diphenylmethane and two ketimine groups in the spacer. The cylinder is longer and slightly wider than the corresponding cylinder containing just diphenylmethane spacers. Inter-strand CH...pi interactions are not observed and this affects the relay of the chiral information within the cylinder; a mixture of rac and meso isomers results, with the meso isomer being the dominant solution species and characterised in the solid state by crystallography. This new cylinder does bind to DNA as confirmed by induced circular dichroism signals in both the metal-to-ligand charge transfer (MLCT) and in-ligand bands of the cylinder. Flow linear dichroism demonstrates that the cylinder binds to DNA in a specific orientation(s) and is consistent with (major) groove-binding as seen for the shorter cylinder. Some DNA bending/coiling is observed but the effect is much less dramatic than observed for the cylinder with diphenylmethane spacers confirming that coiling is not solely a consequence of the tetracationic charge, but rather is related to the precise size and shape of the cylinder.
authors.affiliation: Departaments de Química Orgànica i Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
authors.forename: Carsten
authors.initials: C
authors.lastname: Uerpmann
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Malina
authors.forename: Mirela
authors.initials: M
authors.lastname: Pascu
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Clarkson
authors.forename: Virtudes
authors.initials: V
authors.lastname: Moreno
authors.forename: Alison
authors.initials: A
authors.lastname: Rodger
authors.forename: Anna
authors.initials: A
authors.lastname: Grandas
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hannon
mesh_terms: D001559:Benzhydryl Compounds / Q000737:chemistry; D001665:Binding Sites; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D007097:Imines / Q000737:chemistry; D008024:Ligands; D046911:Macromolecular Substances / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D011725:Pyridines / Q000737:chemistry; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D001559:Benzhydryl Compounds; D007097:Imines; D008024:Ligands; D046911:Macromolecular Substances; D011725:Pyridines; D004247:DNA; C010129:diphenylmethane