Studies on electron spin resonance spectroscopy of biradical molecules containing 14N-O and 15N-O moieties

Abstract

The biradicals with 14N-Oxide and 15N-Oxide at the both ends of a molecule are synthesized for the molecular ruler of protein structure, and a potential device for quantum computing. We also establish a general synthetic method for reliable biradical formation. ESR spectra are recorded for the biradicals containing 15N-Oxide and 14N-Oxide with various interdistance separations. We find that two types of biradicals yielded different ESR spectra depending upon the distance between the 15N-O and 14N-O moieties in a molecule. This is due to electron spin dipole–dipole interaction occurring between the radicals. We also find that there is an indication of isotopic nuclear effects in the dipole–dipole interactions. The present study implies feasibility of the distance measurement between two different N-Oxides containing 14N and 15N isotopes. We conclude that quantum entanglement effects are observed through the dipolar interactions, which enable application of quantum computing devices operating in the liquid state.