硫杂杯[4]芳烃基胶束自组装荧光探针的结构性质及检测性能的研究

doi:10.3964/j.issn.1000-0593(2019)04-1092-05

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Abstract Heavy metal pollution in water is widely concerned because it threatens the ecological environment and human health. The fluorescent probe has been a research focus in this field due to the rapid and efficient detection for heavy metals. Generally, the fluorescent probe structurally includes a receptor recognizing a desired analyte and a fluorophore generating a signal response. It gradually has formed four kinds of structures, which are intrinsic, conjugate, ensembling and template-assisted self-assembled types. In recent years, micellar self-assembled fluorescent probes based on the self-assembly of acceptor and fluorophore in surfactant micelles have attracted attentions. This is due to their simple structure, easy preparation and direct application to water environment. In this paper, the micellar self-assembled fluorescent probes for the detection of Cu²⁺ ions were prepared through self-assembly of surfactant micelles. The p-tert-butylthiacalix[4]arene (TCA) was used as acceptor with excellent bonding property to copper ions. And pyrene, fluoranthene, anthracene, phenanthrene, perylene were used as fluorophore. The fluorescence quantum yields of the micellar self-assembled fluorescent probes were measured by the reference method. The micelle aggregation numbers were determined by the steady-state fluorescence method. At the same time, the influences of fluorophore species and compound surfactants were investigated on detection performances of the probes for Cu²⁺ ions by calculating the fluorescence quenching rate. The experimental results showed that the three surfactants, which are sodium dodecyl sulfate (SDS), Triton X-100 (TX-100) and polyoxyethylene lauryl ether (Brij35), had significant effects on fluorescence quantum yields of the probes. Their fluorescence quantum yields were in the range of 0.25~0.47. And they gradually increased. These indicated that the polarities of the microenvironment inside the micelles were changed by surfactant micelles. And the influences of different types of surfactants on the microenvironment polarity were different. The enhancement of the microenvironment polarity made excited pyrene more stable. The addition of acceptor TCA had little effect on the polarity of the microenvironment in which the fluorophore was located. And it didn’t have a significant influence on the fluorescence quantum yield. However, the micellar aggregation numbers of the probe markedly decreased after the addition of TCA. They were attributed to the fact that the amphiphilic receptor TCA molecules dispersed into the surfactant molecular layer through micelle self-assembly forming co-micelle structure. Thus, the aggregation state of the surfactant molecules was changed. The fluorophore had a significant effect on the detection performance of the probe for Cu²⁺ ions. Under the same conditions, the fluorescence quenching rates of the probes to detect Cu²⁺ ions respectively using fluoranthene, anthracene and phenanthrene as fluorophores were much higher than those of pyrene and perylene. This was mainly due to the different energies released by fluorophore radiative transitions from the excited state to the ground state. And the higher the matching degree with the energy required by the acceptor TCA to recognize Cu²⁺ ions, the greater the fluorescence quenching rate. The compound surfactants could obviously improve the detection performance of the fluorescent probe. When the mole ratios of non-ionic/anionic and non-ionic/cationic surfactants were 7∶3 and 1∶1 respectively, the fluorescence quenching rates were maximum. And the fluorescence quenching rates of the compound surfactants both were higher than those of single surfactant. These showed that the optimal compound ratios of different types of surfactant were quite different. But they both effectively enhanced the dispersibility and self-assembled performance of receptor and fluorophore. Moreover, they improved the detection performance of the probe for Cu²⁺ ions. The results of the thesis will provide a reference for the design and application of novel micellar self-assembled fluorescent probes.

Key words：Thiacalix[4]arene; Micellar self-assembly; Fluorescent probe; Structural property; Detection performance

Received: 2018-03-12 Accepted: 2018-08-06

ZTFLH:

O657.3

Corresponding Authors: HU Xiao-jun E-mail: hu-xj@mail.tsinghua.edu.cn

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2019)04-1092-05 OR https://www.gpxygpfx.com/EN/Y2019/V39/I04/1092