Rigid Multidimensional Alkoxyamines: A Versatile Building Block Library

Abstract

Since the discovery of the "living" free-radical polymerization, alkoxyamines were widely used in nitroxide-mediated polymerization (NMP). Most of the known alkoxyamines bear just one functionality with only a few exceptions bearing two or more alkoxyamine units. Herein, we present a library of novel multidimensional alkoxyamines based on commercially available, rigid, aromatic core structures. A versatile approach allows the introduction of different sidechains which have an impact on the steric hindrance and dissociation behavior of the alkoxyamines. The reaction to the alkoxyamines was optimized by implementing a mild and reliable procedure to give all target compounds in high yields. Utilization of biphenyl, pterphenyl, 1,3,5-triphenylbenzene, tetraphenylethylene, and tetraphenyl-methane results in linear, trigonal, square planar, and tetrahedral shaped alkoxyamines. These building blocks are useful initiators for multifold NMP leading to star-shaped polymers or as a linker for the nitroxide exchange reaction (NER), to obtain dynamic frameworks with a tunable crosslinking degree and self-healing abilities.

Dynamic porous organic polymers with tuneable crosslinking degree and porosity

“…The formation of POPs, with free internal volume, using the nitroxide exchange reaction requires rigid, molecular building blocks, 38,39 therefore we designed molecular building blocks in linear, trigonal, and tetrahedral geometry. 40 Fig. 2 shows the molecular structures of the di-fold, tri-fold, and tetra-fold alkoxyamines 1-3, and the tetra-fold nitroxide 4.…”