荧烷染料的光诱导显色反应和机制的研究

荧烷染料是一类重要的功能性染料,广泛地应用于热敏和压敏记录材料.通常采用在酸作用下,使荧烷染料发生显色反应,由内酯环结构的无色体生成开环结构的有色体.并且通过吨环上不同取代基得到各种色调.荧烷染料有色体不稳定,在一般有机介质中容易发生褪色反应,使得荧烷染料作为记录介质普遍存在着色稳定性差、保存期短的缺点.为了改善有色体的稳定性,人们进行了大量的工作^1-3],但均未取得重要进展.考虑到荧烷染料母核上带有烷胺基取代基,具有电子给体特性,有可能通过电子转移反应的途径进行显色反应.实现这种电子转移显色过程的关键问题是选择合适的电子受体.为此采用盐类化合物如碘盐和硫盐作为电了受体,因为它们容易和不同电子给体组成电子转移光敏反应体系^4-6].因此,本文研究了以荧烷染料为电子给体和碘盐为电子受体的光致电子转移显色反应,并提出了显色反应机制.

INVESTIGATION ON PHOTOINDUCED COLORATION AND MECHANISM OF FLUORANE DYE

Photoinduced coloration system consisting of fluorane dye(FR) and iodonium salt(DPIOB) was investigated. Upon irradiation, the excited fluorane dye and iodonium salt may undergo electron transfer reaction to form FR_·⁺ and IPh₂^· radical pair, the latter rapidly decomposes to phenyl radical (Ph^·) and iodobenze, and the color form of ring opening ester (FRPh) subsequently is formed by radical coupling between FR_·⁺ and Ph^·. The structure of FRPh possesses good stability, and thus it demonstrates electron transfer reaction is one of effective pathway to improve the color stability of fluoranedye.