Dinitroxides for Solid State Dynamic Nuclear Polarization

We have prepared a series of dinitroxides and we investigated their properties as polarizing agents for solid-state nuclear magnetic resonance/dynamic nuclear polarization applications at 100 K, 9.34 T (263 GHz electron paramagnetic resonance and 400 MHz 1 H nuclear magnetic resonance). Our results show that a rigid structure with an orthogonal relative orientation of electron g tensors and the appropriate orientation of the two bonds are required to obtain maximum polarization enhancements. In addition, with dinitroxides exhibiting a long T 1e , the saturation of the irradiated electron spin packet is favored leading to more efficient dynamic nuclear polarization.