Fulgides, photochromic behavior

Aryl-substituted fulgides are the products of condensation of aromatic ketones with succinic anhydride, and form one of the oldest and most important groups of organic photochromic materials241. First discovered in the early part of the last century by Stobbe242, they are now well known to owe their photochromic behavior to reversible (conrotatory)... 

A fulgenolide is a kind of lactone. When R2 is an aromatic group, only the L isomer (9) has photochromic behavior. Fulgenates have excellent photochromic properties, but the absorption band is blue shifted compared with that of the corresponding fulgide. 

Steric Effects on the Photochromic Behavior of the Alkylidene Group of Furyl Fulgides... 

Yokoyama and Kurita demonstrated the design, synthesis, and photochromic behavior of 5-substituted indolyl fulgides (56). The molecular structure and photochromic reactions are shown as Scheme 17. 

Y. Yokoyama, T. Iwai, N. Kera, I. Hitomi, and Y. Kurita, Steric effect of alkylidene groups of fiiryl fulgides on the photochromic behavior, Chem. Lett., 1990, 263-264. 

The spectroscopic data for 43 and 44 are listed in Table 4.10. Fulgides 43a-43f have similar photochromic properties in organic solvents. From Table 4.10 it can be seen that when the electron-donating substituents were introduced into the 5-position of the furyl ring, both fulgides and their colored form (7,7a-DHBF) exhibited bathochromic shifts corresponding to the behavior of compound 44f ( ydX = 612 nm... 

---