| 摘要 |
A reversible thermochromic system comprising a) a compound of the formula (I) or a tautomer thereof (I) wherein R1 is C1-C18alkyl, C2-C18alkenyl, C3-C12cycloalkyl, C3-C12cycloalkyl substituted by 1, 2 or 3 C1-C4alkyl; or C7-C12phenylalkyl; R2 and R3 are hydrogen or R2 and R3 together form a group —CH═CH—CH═CH—; and R4 is hydrogen, —NO2, —SO2—R1 or (4-nitrophenyl)azo; and b) a compound containing a group of the formula (II).
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