| 摘要 |
PROBLEM TO BE SOLVED: To obtain a photochromic compound having high color-developing sensitivity, rapid discoloring rate, and good durability of photochromic properties. SOLUTION: This new chromene compound having a condensed ring formed by binding a specific divalent group to carbon atoms at 4- and 5-positions of a fluoreno group, and spiro-bonded to 1-position of an indene ring as a basic structure, a condensed ring formed by binding a specified divalent group bound to the carbon atoms at 5- and 6-positions of the chromene ring, and a specific substituent group bound to the carbon atom at the 2-position of the chromene ring, and represented by the formula.
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