Chanmungkalakul Supphachok, Ervithayasuporn Vuthichai, Boonkitti Patcharaporn, Phuekphong Alisa, Prigyai Nicha, Kladsomboon Sumana, Kiatkamjornwong Suda
Department of Chemistry , Center of Excellence for Innovation in Chemistry (PERCH-CIC) , Center for Inorganic and Materials Chemistry , Faculty of Science , Mahidol University , Rama VI Road, Ratchathewi , Bangkok 10400 , Thailand . Email:
Department of Radiological Technology , Faculty of Medical Technology , Mahidol University , Nakhon Pathom 73170 , Thailand.
Chem Sci. 2018 Sep 25;9(40):7753-7765. doi: 10.1039/c8sc02959h. eCollection 2018 Oct 28.
Anthracene-conjugated octameric silsesquioxane (AnSQ) cages, prepared Heck coupling between octavinylsilsesquioxane (OVS) and 9-bromoanthracene, thermodynamically display intramolecular excimer emissions. More importantly, these hosts are sensitive to each anionic guest, thereby resulting in change of anthracene excimer formation, displaying the solvent-dependent fluorescence and allowing us to distinguish up to four ions such as F, OH, CN and PO by fluorescence spectroscopy. Depending on the solvent polarity, for example, both F and CN quenched the fluorescence emission intensity in THF, but only F could enhance the fluorescence in all other solvents. The presence of PO results in fluorescence enhancements in high polarity solvents such as DMSO, DMF, and acetone, while OH induces enhancements only in low polarity solvents ( DCM and toluene). A picture of the anion recognizing ability of AnSQ was obtained through principal component analysis (PCA) with NMR and FTIR confirming the presence of host-guest interactions. Computational modeling studies demonstrate the conformation of host-guest complexation and also the change of excimer formation. Detection of F, CN and OH by AnSQ hosts in THF is noticeable with the naked eye, as indicated by strong color changes arising from charge transfer complex formation upon anion addition.
通过八乙烯基倍半硅氧烷（OVS）与9-溴蒽之间的Heck偶联反应制备的蒽共轭八聚倍半硅氧烷（AnSQ）笼在热力学上呈现分子内准分子发射。更重要的是，这些主体对每种阴离子客体都很敏感，从而导致蒽准分子形成的变化，表现出溶剂依赖性荧光，并使我们能够通过荧光光谱法区分多达四种离子，如F⁻、OH⁻、CN⁻和PO₄³⁻。例如，根据溶剂极性，F⁻和CN⁻在四氢呋喃（THF）中均淬灭荧光发射强度，但只有F⁻能在所有其他溶剂中增强荧光。PO₄³⁻的存在会导致在高极性溶剂如二甲基亚砜（DMSO）、二甲基甲酰胺（DMF）和丙酮中荧光增强，而OH⁻仅在低极性溶剂（二氯甲烷（DCM）和甲苯）中诱导荧光增强。通过主成分分析（PCA）获得了AnSQ阴离子识别能力的图像，核磁共振（NMR）和傅里叶变换红外光谱（FTIR）证实了主客体相互作用的存在。计算模型研究表明了主客体络合的构象以及准分子形成的变化。AnSQ主体在THF中对F⁻、CN⁻和OH⁻的检测肉眼可见，如添加阴离子后电荷转移络合物形成导致的强烈颜色变化所示。
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