Control of the Association of Indolylfulgimide with Bis(acylamino)pyridine by Photochromism

Abstract

Abstract While the association constant of the colored form of a thermally irreversible photochromic indolylfulgimide with 2, 6-bis (octanoylamino)pyridine in toluene at 21 °C was 156 ± 11 mol−1 dm3 through triplex hydrogen bonding, that of its colorless form, generated by visible-light irradiation, was increased to 885 ± 63 mol−1 dm3. This result was supported by PM3 semiempirical molecular–orbital calculations that the difference of the association constants between the C-form and the E-form was mainly due to differences in the structures and conformations of the imide moiety.