Intramolecular Hydrogen Bonding Effect on the Electron-Transfer Thermodynamics of a Series of o -Nitrobenzyl Alcohol Derivatives.

From thermoelectrochemical experiments and electronic structure calculations of a series of nitrobenzyl alcohol derivatives, the effect of intramolecular hydrogen bonding (IHB) on the electron transfer thermodynamics is discussed on a molecular basis. A linear correlation between formal reduction potential ( E 1/2 ) values and temperature was obtained for the temperature range from 300 to 350 K. Estimated electron transfer entropy values (Δ S )─determined from this dependence─and the enthalpy (ΔΔ H ) changes relative to o -nitrobenzyl alcohol confirmed that the effect of the formation of IHB proved to be decisive in the charge-transfer thermodynamics. The possibility of intermolecular hydrogen bonding is further discussed upon comparing thermodynamic data among three different solvents.