Counting the Monomers in Nanometer-Sized Oligomers by Pulsed Electron−Electron Double Resonance

• DOI: 10.1021/ja065787t
• Publication Date: 2007-05-08T11:00:39Z
• Authors: Bela E. Bode; Dominik Margraf; Jörn Plackmeyer; Gerd Dürner; Thomas F. Prisner; Olav Schiemann
• Keywords: Nanometre; Electron counting

In a lot of cases active biomolecules are complexes higher order, thus methods capable counting the number building blocks and elucidating their geometric arrangement needed. Therefore, we experimentally validate here spin-counting via 4-pulse electron−electron double resonance (PELDOR) on well-defined test samples. Two biradicals, symmetric an asymmetric triradical, tetraradical were synthesized in convergent reaction scheme palladium-catalyzed cross-coupling reactions. PELDOR was then used to obtain information spin centers per molecule single experiment. The measurement yielded expected distances (2.2−3.8 nm) showed that different spin−spin one can be resolved even if difference amounts only 5 Å. spins n has been determined 2.1 both 3.1 3.0 triradicals, respectively, 3.9 tetraradical. overall error found 5% for up four spins. Thus, this method is valuable tool determine constituting spin-bearing monomers biologically relevant homo- heterooligomers how oligomerization state changes during function.