Selective Transition Enhancement in a g‐Engineered Diradical #DNPNMR

Published: Friday, 05 July 2024 - 10:00 -0400

Author: Thorsten Maly

Komeda, Joe, Athanassios K. Boudalis, Nicolas Montenegro‐Pohlhammer, Cyril Antheaume, Asato Mizuno, Philippe Turek, and Mario Ruben. “Selective Transition Enhancement in a g‐Engineered Diradical.” Chemistry – A European Journal, May 3, 2024, e202400420.

A diradical with engineered g-asymmetry was synthesized by grafting anitroxide radical onto the [Y(Pc)2]* radical platform. Various spectroscopic techniques and computational studies revealed that the electronic structures ofthe two spin systems remained minimally affected within the diradical system. Fluidsolution Electron Paramagnetic Resonance (EPR) experiments revealed aweak exchange coupling with j J j ~0.014 cm 1, subsequently rationalized by CAS-SCF calculations. Frozen solution continuous-wave (CW) EPR experiments showed a complicated and power-dependent spectrum that eluded analysis using the point-dipole model. Pulse EPR manipulations with varying microwave powers, orunder varying magnetic fields, demonstrated that different resonances could beselectively enhanced orsuppressed, based ontheir different tipping angles. Inparticular, Field-Swept Echo-Detected (FSED) spectra revealed absorptions ofMW power-dependent intensities, while Field-Swept Spin Nutation (FSSN) experiments revealed two distinct Rabi frequencies. This study introduces amethodology tosynthesize and characterize g-asymmetric two-spin systems, ofinterest intheimplementation ofspin-based CNOT gates.