Division of Material Chemistry, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Ishikawa, 920-1192, Japan.
Photochem Photobiol. 2019 May;95(3):762-772. doi: 10.1111/php.13071. Epub 2019 Jan 10.
Substances containing ethynylpyrenes linked to either one or four benzocrown ethers were synthesized, and their absorption and fluorescence spectroscopic responses to metal ions were assessed. Addition of metal perchlorates to solutions of these substances promotes short wavelength shifts in their absorption and fluorescence maxima and increases in their fluorescence intensities. The magnitudes of the fluorescence intensity increases are dependent on the ring size and number of the crown ether and the nature of the metal cation. Association constants for complex formation were calculated using fluorescence intensity versus concentration data. Analysis using Job's plots showed that the substances containing one benzocrown ether moiety form 1:1 complexes with metal ions. Results of experiments employing repeated addition and removal of Mg(ClO ) demonstrate that the ON-OFF fluorescence response can be repeated at least three times. Results of molecular orbital calculations show that complexation with metal ions lowers the energies of both the π and π* levels of the ethynylpyrene moiety and that in some cases the vacant orbital on the metal becomes the LUMO of the complex. An explanation of the spectroscopic changes promoted by metal ions is proposed in terms of electrostatic repulsion and structural regulation.
合成了含有一个或四个苯并冠醚的乙炔基芘衍生物，并评估了它们对金属离子的吸收和荧光光谱响应。向这些物质的溶液中加入高氯酸盐会促进它们的吸收和荧光最大波长发生短波长位移，并增加它们的荧光强度。荧光强度增加的幅度取决于冠醚的环大小和数量以及金属阳离子的性质。使用荧光强度与浓度数据计算了配合物形成的缔合常数。Job 图分析表明，含有一个苯并冠醚部分的物质与金属离子形成 1:1 配合物。使用反复加入和去除 Mg(ClO )的实验结果表明，ON-OFF 荧光响应可以至少重复三次。分子轨道计算的结果表明，金属离子的络合降低了乙炔基芘部分的π和π*能级的能量，并且在某些情况下，金属上的空轨道成为配合物的 LUMO。根据静电排斥和结构调节，提出了金属离子促进的光谱变化的解释。
