Browsing by Subject "Colorimetric"
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Item Calix[4]arene-based ion or ion-pair receptors(2016-05) Yeon, Yerim; Sessler, Jonathan L.; Liu, Hung-wen; Keatinge-Clay, Adrian T; Dong, Guangbin; Kerwin, Sean MCalix[4]arene derivatives are one of the most important supramolecular scaffolds. They have been extensively exploited to build more elaborate systems. Calix[4]arene derivatives can stabilize host-guest complexes with various ions and neutral molecular guests through non-covalent interactions (e.g., hydrogen bonding, electrostatic interactions and cation-π interactions). This dissertation describes efforts to develop more efficient calix[4]arene-based ion and ion-pair receptors. Chapter 1 describes an overview of sensitive ion selective chromogenic and fluoregenic sensors based on calix[4]arene derivatives. Chapter 2 details a chromogenic calix[4]arene-calix[4]pyrrole sensor system formed by appending an indane substituent to the β-pyrrole position of the calix[4]pyrrole portion of the hybrid and its use in detecting cesium salts. The indane substituted calix[4]arene-calix[4]pyrrole system gives rise to a colorimetric response when only exposed to simple ion pairs containing the cesium cation. Chapter 3 describes amido-indole incorporated calix[4]arene anion receptors. An amido-indole moieties appended calix[4]arene provides multiple hydrogen bond donors for the interaction with anions. In Chapter 4, graphene field-effect transistors (GFETs) are introduced for cesium ion sensing based on electrostatic measurements. In this work, a crown-6-ether strapped calix[4]arene derivative that adopts a cesium ion selective conformation was prepared. Then, it was attached to various graphene field-effect transistors (GFETs) via π−π interactions. The co-complexation of Cs⁺ ion and calix[4]arene receptor on the GFETs alters the electronic behavior of the system in an ion and concentration dependent manner. This work serves to extend the fundamental chemistry of calix[4]arene-based cesium ion recognition to new research areas. Lastly, an experimental section and characterization data are provided in Chapter 5.Item Development of a reusable colorimetric calcium sensor based on a calix[4]arene-functionalized glass surface(2013-05) Yeon, Yerim; Sessler, Jonathan L.A dual functional chromogenic calix[4]arene, which contains both hydroxy azophenols and triazoles for colorimetric sensing and cationic recognition, respectively, has been synthesized. This system was further functionalized with dimethallylsilane to permit grafting to a glass surface. This grafting may be used to produce a surface modified glass slides that act as reusable ion-selective colorimetric sensors. UV/Vis spectral studies revealed that this compound is capable of binding the calcium cation in aqueous media and producing an easily detectable color change. The same is true for the modified surface setup. For the free receptor in acetonitrile solution, the absorption maximum undergoes a red shift from 390 nm to 496 nm upon exposure to calcium cations. In the case of the modified surface, exposure to acetonitrile solution of calcium perchlorate leads to a change in color from orange to red. Washing with acetone serves to remove the metal cations from the calix[4]arene-functionalized glass and restore the original orange color. The system is then ready for reuse. Specifically, following treatment with acetone, the glass may be submerged in a metal solution once again. In the case of exposure to calcium salts, this re-exposure results in a color change analogous to what was seen for a pristine system. In accord with design expectations, this process may be repeated several times. On the basis of this reproducibility, we think this system meets the reusability requirements necessary for the development of a practical sensor device.