Spectroscopic properties of BIPS probes in ethanol.

aReference compound 6-NO2-BIPS;bPhotochemistry of 1e and 1g is too low to be measured;cThe MC-state of 2f does not convert back to the SP-state even with light irradiation;dThe MC-state of 1f is thermally stable in the dark at room temperature but it converts back to SP state upon exposure to green light;eColorability of the probe after exposure to 365 nm light for 30 s;fColorability of the probe after exposure to 405 nm light for 60 s.