Li Yongrong, Washino Yusuke, Hyakutake Tsuyoshi, Michinobu Tsuyoshi
Department of Organic and Polymeric Materials, Tokyo Institute of Technology.
Innovative Materials and Resources Research Center (iMaRRC), Public Works Research Institute.
Anal Sci. 2017;33(5):599-604. doi: 10.2116/analsci.33.599.
Side chain clicked polystyrene derivatives formed by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction showed colorimetric ion sensing behaviors when donor-acceptor chromophores, prepared by a [2+2] cylcoladdition-retroelectrocyclization between electron-rich alkynes and tetracyanoethylene (TCNE)/7,7,8,8-tetracyanoquinodimethane (TCNQ), were attached to the triazole rings. The metal ion sensing behaviors could be explained according to the theory of hard and soft acids and bases (HSAB). Hard acidic metal ions were mainly recognized by the hard basic anilino-nitrogen moieties, resulting in a decrease in the charge-transfer (CT) bands. In contrast, soft acidic metal ions led to a bathochromic shift in the CT bands due to the selective interactions with the soft basic cyano-nitrogen atoms. With the triazole spacers, more soft (and/or borderline) metal ions were recognized by the donor-acceptor chromophores probably due to more space for the various sized metal ions. The chemodocimetric anion sensing behaviors of the clicked polystyrenes were almost the same as those of the counter polystyrenes without the triazole spacers. Overall, the triazoles in this study do not serve as colorimetric sensor units towards both metal ions and anions, but they are effective spacers between the polymer main chain and ion sensing donor-acceptor side chain chromophores.
通过铜（I）催化的叠氮化物-炔烃环加成（CuAAC）反应形成的侧链点击聚苯乙烯衍生物，当通过富电子炔烃与四氰基乙烯（TCNE）/7,7,8,8-四氰基对苯二醌二甲烷（TCNQ）之间的[2+2]环加成-逆电环化反应制备的供体-受体发色团连接到三唑环上时，表现出比色离子传感行为。金属离子传感行为可以根据软硬酸碱（HSAB）理论来解释。硬酸性金属离子主要由硬碱性苯胺基氮部分识别，导致电荷转移（CT）带减少。相反，软酸性金属离子由于与软碱性氰基氮原子的选择性相互作用，导致CT带发生红移。有了三唑间隔基，供体-受体发色团可能识别出更多软（和/或边界）金属离子，这可能是因为为各种尺寸的金属离子提供了更多空间。点击聚苯乙烯的化学计量阴离子传感行为与没有三唑间隔基的反聚苯乙烯几乎相同。总体而言，本研究中的三唑并非对金属离子和阴离子都用作比色传感器单元，但它们是聚合物主链与离子传感供体-受体侧链发色团之间的有效间隔基。
