Mono and Dumbbell Silsesquioxane Cages as Dual-Response Fluorescent Chemosensors for Fluoride and Polycyclic Aromatic Hydrocarbons

Abstract

Pyrene-conjugated monomeric (2) and dimeric (5) shaped-silsesquioxane (SQ) cages, as chemical sensors for detecting fluoride and polycyclic aromatic hydrocarbons (PAHs), were prepared by Heck-coupling reactions between vinyl-functionalized SQ cages and bromo-substituted pyrenes. These sensors give a remarkable deep-blue fluorescence, which could be quenched in the presence of fluoride and electron-withdrawing PAHs. Interestingly, both sensors 2 and 5 show a rapid detection toward PAHs, while a high number of vinylic silicon atoms in a monomeric cage-based sensor 2 detected fluoride relatively faster than a bulky dumbbell sensor 5. In addition, these sensors also provide a naked-eye color of fluoride detection through an intramolecular charge-transfer presenting in yellow and pink (λ max ∼ 495 and 520 nm) for mono and dumbbell sensors, respectively. The limit of detection for fluoride and PAH (e.g., 1pyrenecarboxaldehyde and 1-nitropyrene) detections is approximately 1−3 μM. The computational calculation for the further mechanistic study of PAHs detection revealed that an emission of SQ was absorbed by PAHs, thereby resulting in aggregationcaused quenching.

Cagelike Octacopper Methylsilsesquioxanes: Self-Assembly in the Focus of Alkaline Metal Ion Influence—Synthesis, Structure, and Catalytic Activity

“…It is known that variations of the nature of alkaline metal ions strongly influence the structural features of phenylsurrounded CLMSs, especially in the context of supramolecular aggregation observed for large-sized ions (K, Rb, Cs) [ 16 , 23 , 25 , 47 , 60 ]. For the method of synthesis of methylsurrounded Cu-CLMSs, a universal approach that included alkaline hydrolysis [ 61 , 62 , 63 ] of MeSi(OMe) 3 assisted by the action of corresponding hydroxide MOH (M = Na, K, Rb, or Cs), was chosen. Then in situ formed alkaline metal siloxanolate [PhSi(O)OM] x species were brought into the exchange interaction with copper(II) chloride ( Scheme 1 ).…”

Ultrafast synthesis of silicone elastomers using silsesquioxane cages as crosslinkers

“…9,10 POSS has a cage-like structure, and is often used as a building block to modify materials' properties to achieve high surface area, fire-resistance, low heat conduction, inertness or even to increase the robustness of a material. [11][12][13] So far, the synthesis of silicone elastomers from the above mentioned materials has required several steps, the requirement of a template, fillers, and a long reaction time. [14][15][16][17][18] Herein, a superfast combination reaction between a cyclic tetrasiloxane and POSS can form a silicone elastomer via an anionic ring-opening polymerization.…”

Development of a fluoride-anion sensor based on aggregation of a dye-modified polyhedral oligomeric silsesquioxane

“…[17][18][19][20] As POSS molecules contain silicon atoms, they exhibit a unique affinity for fluoride anions and their functions such as fluoride encapsulation [21][22][23][24] and rearrangement reaction have been widely studied. 25,26 POSS derivatives have been also incorporated in several fluoride sensors for their chemical and thermal stability and versatile molecular designs towards various detection modes such as turn-on 27 and turn-off responses 28,29 and color changes. [30][31][32][33][34] In these studies, decomposition of the POSS nanocage by fluoride anions is a key step.…”

“…From the integration ratio of the signal peak from the triplet amide proton (8.81 ppm), it was confirmed that eight C343 units can be covalently attached to the POSS moiety. The signal at À66.9 ppm in the 29 Si NMR spectrum indicates that the cubic T8 POSS cage should remain intact (Fig. S3, ESI †).…”

“…S12, ESI †). Moreover, in 29 Si NMR spectra, slightly shifted peak as well as the new peak were observed after addition of TBAF, and they should be originated from C343-POSS and damaged POSS (Fig. S13, ESI †).…”