EPR probes with well-defined, long distances between two or three unpaired electrons
The synthesis of rod- and star-shaped compounds carrying two or three spin labels as end groups is described. The unpaired electrons are 2.8-5.1 nm apart from each other. The shape-persistent scaffolds were obtained through Pd-Cu-catalyzed alkynyl-aryl coupling and Pd-Cu-catalyzed alkyne dimerization in the presence of oxygen using p-phenyleneethynylene as the basic shape-persistent building block. The spin label 1-oxyl-2,2,5,5-tetramethylpyrroline-3-carboxylic acid (4) was attached through esterification of the terminal phenolic OH groups of the scaffold.
Godt
A
Max-Planck-Institut fur Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany.
Franzen
C
Veit
S
Enkelmann
V
Pannier
M
Jeschke
G