Effect of electron-donating and electron-accepting substituents on photo- and thermochromic properties of indolinospiropyrans

1. We have measured the energy barriers to conversion of the colorless form of five indolinospiropyrans with different 8′-substituents. 2. We have measured the dependence of the angle between the oscillators of the electronic transitions of the colored form of the spiropyrans on the donor-acceptor properties of these substituents. 3. The introduction of substituents into the pyran fragment of the spiropyran molecule controls the pathway for the color reaction and the equilibrium among the stereoisomers of the colored form.