Nanoscale solvent organization in metal-organic framework ZIF-8 probed by EPR of flexible β-phosphorylated nitroxides.

Metal-organic frameworks (MOFs) draw increasing attention as nanoenvironments for chemical reactions, especially in the field of catalysis. Knowing the specifics of MOF cavities is decisive in many of these cases; yet, obtaining them remains very challenging. We report the first direct assessment of the apparent polarity and solvent organization inside MOF cavities using a dedicated structurally flexible spin probe.

Fullerene-based triplet spin labels: methodology aspects for pulsed dipolar EPR spectroscopy.

Triplet states of photoexcited organic molecules are promising spin labels with advanced spectroscopic properties for pulsed dipolar electron paramagnetic resonance (PD EPR) spectroscopy. Recently proposed triplet fullerene labels have shown great potential for double electron-electron resonance (DEER) distance measurements as "observer spins" due to a high quantum yield of the triplet state, hyperpolarization and relatively narrow EPR spectra. Here, we demonstrate the applicability of fullerene labels to other PD EPR techniques, such as relaxation induced dipolar modulation enhancement (RIDME) and laser induced magnetic dipolar spectroscopy (LaserIMD).