Thermal isomerization of photochemically synthesized (Z)-9-styrylacridines. An unusually high enthalpy of Z→E conversion for stilbene-like compounds

Eight stable (Z)-9-styrylacridines, have been photochemically synthesized and their enthalpies of thermal isomerization (ΔHZ→E) determined by means of thermal analysis. The enthalpy values were found to be influenced by both electronic and steric effects. The title compounds were used as models in order to gain insight into the energetic implications involved in the Z→E isomerization process and its applicability to photochemical energy conversion by irradiation in the visible wavelength region.