Fluorescence‐Tuned Polyhedral Oligomeric Silsesquioxane‐Based Porous Polymers

Abstract

Two series of new polyhedral oligomeric silsesquioxane (POSS)-based fluorescent hybrid porous polymers, HPP-1 and HPP-2, have been prepared by the Heck reaction of octavinylsilsesquioxane with 2,2',7,7'-tetrabromo-9,9'-spirobifluorene and 1,3,6,8-tetrabromopyrene, respectively. Three sets of reaction conditions were employed to assess their effect on fluorescence. These materials exhibit tunable fluorescence from nearly no fluorescence to bright fluorescence both in the solid state and dispersed in ethanol under UV light irradiation by simply altering the reaction conditions. We speculated that the difference may be attributable to the fluorescence quenching induced by Et3 N, P(o-CH3 Ph)3 , and their hydrogen bromide salts employed in the reactions. This finding could give valuable suggestions for the construction of porous polymers with tunable/controllable fluorescence, especially those prepared by Heck and Sonogashira reactions in which these quenchers are used as organic bases or co-catalysts. In addition, the porosities can also be tuned, but different trends in porosity have been found in these two series of polymers, which suggests that various factors should be carefully considered in the preparation of porous polymers with tunable/controllable porosity. Furthermore, HPP-1 c showed moderate CO2 uptake and fluorescence that was efficiently quenched by nitroaromatic explosives, thereby indicating that these materials could be utilized as solid absorbents for the capture and storage of CO2 and as sensing agents for the detection of explosives.

Octa[4‐(9‐carbazolyl)phenyl]silsesquioxane‐Based Porous Material for Dyes Adsorption and Sensing of Nitroaromatic Compounds

“…The crude product was purified by recrystallization from methanol to get al ight gray powder. 1 HNMR (8.2-6.2 ppm, broad), 29 Si MAS NMR (À79.1 ppm), 13 CC P/MAS NMR(CÀSi:1 06.8, CÀH: 118.1,121.9, CÀN: 138.0 ppm), FT-IR (n SiÀOÀSi, 1117cm À1 , n CÀN ,1450 cm À1 )( Figure S13). HPP was synthesized by the oxidative coupling polymerization (Scheme 1).…”

“…Some silses-quioxanes-based hybrid fluorescent porous polymers were prepared by combining silsesquioxane unit with different organic chromophores and their potentials in detecting nitroaromatic explosives were explored due to high sensitivity,c onvenience and low-cost. [13] Carbazole-basedp orouso rganic polymers have been widely investigateds ince they possess large specific surfacea reas and an intrinsic photoluminescence chromophore. [4f, 14] By far,t here is no report on silsesquioxane-based carbazole-functionalized porousp olymer.I nt he present study, we utilize octa[4-(9-carbazolyl)phenyl]silsesquioxane (OCPS) as ap rimary buildingu nit for the synthesis of an ew hybrid fluorescent porous polymer (HPP)v ia FeCl 3 -mediated oxidative cross coupling reaction( Scheme 1).…”

The Role of Polyhedral Oligomeric Silsesquioxanes in Optical Applications

“…[ 47,49,56,64 ] Moreover, in solid‐state probes, the POSS unit may be used to control the 3D structure of the bulk material, increasing the internal porosity and thus sensitivity of the resultant sensor. [ 49,56,64–66 ]…”

“…A POSS‐spirobifluorene‐based HPP later developed by the same group showed further improved fluorescence quenching efficiency in the presence of nitroaromatic analyte solutions, with increased Stern–Volmer constants reaching 16 344 M −1 for TNT. [ 66 ]…”

“…Moving away from PNCs, polyfunctional POSS‐based polymers, referred to as fluorescent HPPs, have been synthesized with potential applications in light‐emitting devices. [ 32,66 ] Wang et al demonstrated the synthesis of a series of two HPPs synthesized via the Heck reaction of octavinylsilsesquioxane with 2,2′,7,7′‐tetrabromo‐9,9′‐spirobifluorene and 1,3,6,8‐tetrabromopyrene. [ 66 ] Controlling the reaction conditions—such as altering the catalyst used in the Heck reaction—resulted in tunable PL in both solid state and solution.…”