| 摘要 |
The present invention provides a photochromic compound that is colored whe n irradiated with visible light and quickly faded when set in a dark place. Th e photochromic compound according to the present invention is expressed by the following general formula (I): <IMG> where each of A1, A2 and A3 is a five-member rings forming a 6.pi.-electron system, the three rings being identical, partially identical or totally different from each other, and each ring may have a substituent; B1 and B2 are functional groups, each having an atom ic number of five or larger, including a ring compound, and bonded to the 2-carbon of eac h of A2 and A3, respectively; and R1, R2 and R3 are substituents identical to or different from each other. This compound is highly colorable and durable even when it is dispersed into plastic macromolecular materials. Therefore, it is suitable as a dye material for sunglasses or similar products.
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