Proton hyperfine structure in the ESR ΔMs = ±2 transitions of the triplet states of 1-naphthol and 1-naphtholate in glassy matrices. A parallel-polarized ESR study

The effects of deprotonation on the spin distribution of 1-naphthol (1-ROH) in the lowest excited triplet (T1) state have been studied by the parallel-polarized ESR technique. The proton hyperfine structures in ΔMs = ±2 transitions have been observed for the T1 states of 1-ROH and 1-naphtholate (1-RO-) in random rigid solutions of ethanol at 77 K. The α-proton hyperfine splitting of 1-RO- is smaller than that of 1-ROH. With the aid of the spin-density calculation within McLachlan's approximation, the effect of deprotonation on the spin densities at the α-carbon atoms of 1-ROH in the T1 state is discussed. This is the first report of the proton hyperfine structure of a T1 organic molecule in an ionic form