SPIN IDENTIFICATION OF POLYIONIC HIGH-SPIN ARYL-BASED HETEROATOMIC SYSTEMS BY 2D ELECTRON-SPIN TRANSIENT NUTATION (2D-ESTN) SPECTROSCOPY

Molecular design, generation, and spin identification of polyionic hig h spins with heteroatomic R-conjugation are described. The molecular d esign was based upon the pi-topological pseudo-degeneracy of HOMO's fo r high-spin polycations and LUMO's for high-spin polyanions. The pseud o-degeneracy originates in heteroatomic perturbation and high spin pre ference in their ground state is driven by meta-or 1,3,5-connectivity of heteroatomic sites giving rise to additive dynamic spin polarizatio n. Polyionic high spins were generated by chemical oxidation or reduct ion in solution. Thus, the polyions were observed in a rigid glass sol ution containing reaction mixture. For such complex spin systems their reliable spin identification is essential and, therefore, we employed field-swept 2D electron spin transient nutation (2D-ESTN) spectroscop y. In this work, we have developed such a 2D-ESTN spectroscopy as dese rves to enhance spectral resolution in complex spin mixture of non-ori ented systems. An unequivocal and facile spin identification of the po lyions was carried out, demonstrating that the topological version of the molecular design has been established for polyionic high-spin pref erence in heteroatomic pi-conjugation. It has turned out that tile 2D- ESTN spectroscopy is feasible for high spin mixture of any kinds and p rovides us with direct experimental discrimination between high spins of different spin multiplicities.