| 摘要 |
The present invention relates to a time temperature indicator for indicating a temperature change over time comprising one dimeric or trimeric spiropyran indicator of the formula I or II wherein R-Rindependently of one another is hydrogen,-CCalkoxy, halogen, CF, -CCalkyl or-NO, Ris hydrogen, halogen,-C-Calkoxy,-COOH,-COO-C-Calkyl,-CFor phenyl; Ris hydrogen or Rand Rform together a phenyl ring; Ris-C-Calkyl Ris-C-Calkyl, or together with Rform a 5-6 membered ring L is a divalent linker; L′ is a trivalent linker.
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