title: Effects of subtle differences in ligand constitution and conformation in metallo-supramolecular self-assembled polygons.
abstract: 3,3'-Bis(pyridin-[n]-ylethynyl)biphenyl (n = 3, 4) and the corresponding 2,2'-bipyridines assemble with (dppp)Pt(II) triflate into metallo-supramolecular polygons. Depending on the position of the terminal pyridine N atoms, the assembly reaction leads to different equilibrium products. With the slow ligand exchange on Pt(II) complexes, the equilibrium is reached on a many-hour time-scale. During the assembly process, larger polygons form under kinetic control. This was confirmed by time-dependent (1)H and (31)P NMR spectroscopy in line with complementary ESI mass spectrometric experiments. The constitutional difference in the pyridine N-atom position is reflected in the tandem mass spectra of the complex ions. In addition, a highly specific fragmentation process of mass-selected M(3)L(3) ions was observed, which proceeds through a ring contraction yielding smaller M(2)L(2) ions.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität, Takustr. 3, D-14195, Berlin, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Brusilowskij
authors.forename: Egor V
authors.initials: EV
authors.lastname: Dzyuba
authors.forename: Ralf W
authors.initials: RW
authors.lastname: Troff
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Schalley