title: Designer dendrimers: branched oligosulfonimides with controllable molecular architectures.
abstract: The synthesis of "designer" dendrimers and dendrons with sulfonimide units at every branching point is reported. The synthesis is based on a series of (regio)selective functionalization reactions of amines and sulfonamides allowing precise control of the dendrimers' shape, the number of branches in each generation, and their peripheral decoration with functional groups. In principle, structurally different branches can be incorporated at any position within the dendrimer structure at will. Structurally perfect symmetrical and two-faced "Janus"-type dendrimers, as well as dendrimers and dendrons with intended interstices were synthesized on a preparative scale and fully characterized. Oligosulfonimide dendrons of various generations bearing an aryl bromide functional group at their focal points were attached to a p-phenylene core with the aid of Suzuki cross-coupling reactions resulting in dendrimers with photoactive terphenyl cores. The structure and the high purity of all dendritic sulfonimides were confirmed by means of (1)H and (13)C NMR, electrospray ionization mass spectrometry (ESI-MS), and elemental analysis. The utility of MALDI-TOF mass spectrometry for the analytical characterization of these dendrimers was evaluated in comparison to electrospray ionization. Two model branched oligosulfonimides were characterized in the solid state by single-crystal X-ray analysis. Reaction selectivities and conformation of sulfonimide branching points were rationalized by DFT calculations.
authors.affiliation: Institute of Polymers, Department of Materials, ETH Zurich, HCI G 527, 8093 Zurich, Switzerland.
authors.forename: Oleg
authors.initials: O
authors.lastname: Lukin
authors.forename: Volker
authors.initials: V
authors.lastname: Gramlich
authors.forename: Ramchandra
authors.initials: R
authors.lastname: Kandre
authors.forename: Igor
authors.initials: I
authors.lastname: Zhun
authors.forename: Thorsten
authors.initials: T
authors.lastname: Felder
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Schalley
authors.forename: Grigoriy
authors.initials: G
authors.lastname: Dolgonos