Surfactant structure effects on binding with oppositely charged polyelectrolytes observed by fluorescence of a pyrene probe and label

Effect of Solvent Quality toward the Association of Succinimide Pendants of a Modified Ethylene−Propylene Copolymer in Mixtures of Toluene and Hexane

“…Although the fluorescence spectrum of a pyrene molecule is known to provide information about the polarity of its microenvironment by measuring the I 3 / I 1 ratio of the third ( I 3 ) to the first ( I 1 ) vibronic band of the fluorescence spectrum, this effect is usually much less pronounced with pyrenyl pendants such as those of Py−EP . Nevertheless there have been several examples in the literature where the I 3 / I 1 ratio of pyrene labeled polymers has been reported in order to provide information about the micropolarity of the environment surrounding the pyrenyl pendants. − When the I 3 / I 1 ratio is recorded in Figure as a function of the hexane content of the mixtures, it shows a significant increase from 0.85 in toluene up to 1.15 in hexane. This is a rather unexpected result because the I 3 / I 1 ratio is supposed to depend on the polarity of the microenvironment experienced by the pyrenyl pendant.…”

Encapsulating Pyrene in a Metal–Organic Zeolite for Optical Sensing of Molecular Oxygen

“…As shown in Figure S8, pyrene@MAF-4 had no luminescence change when exposed in the vapors of nitroaromatic compounds such as nitrobenzene, 2,6-dinitrotoluene, and 2,4-dinitrotoluene, confirming that the small apertures of MAF-4 can allow the oxygen molecules but prevent other larger molecules to interact with the encapsulated pyrene molecules. On the contrary, when pyrene molecules are dissolved in solvents or dispersed in other porous matrixes such as mesoporous ormosil and organic polymers, their fluorescence can be effectively quenched by both oxygen and nitroaromatic compounds and cannot distinguish these guests, − because oxygen molecules enhance the intersystem crossing of pyrene excitons, while nitroaromatic compounds can break the π–π* stacking of pyrene excimers. − , …”

“…Optical chemical sensors get more and more attention for their advantages of high sensitivity, fast response, no analyte consumption, and no electrical connection. , With high fluorescence quantum yield, suitable oxygen sensitivity, and fairly good photostability, pyrene is a widely used oxygen-sensing probe, even though it must be dispersed in gas permeable organic polymers to allow effective interaction with oxygen molecules. − The pyrene–polymer composites are usually coated on solid surfaces to serve as pressure-sensitive paints (PSPs) for studies of aerodynamics and fluid mechanics, as the fluorescence image directly correlates with the spatial distribution of air (oxygen) pressure and wind speed according to the Dalton partial pressure law and the dynamic pressure function. − Unfortunately, pyrene is a carcinogen and environmental pollutant, and the pyrene-based paints are easy to degrade because pyrene molecules tend to aggregate and evaporate especially at high temperatures and low pressures. , Some pyrene derivatives having good affinity or covalently connected with the polymer matrixes (including organic polymers and coordination polymers) were prepared to reduce the aggregation/leak effects, but complicated organic syntheses are required for these strategies. − ,− Moreover, the fluorescence of pyrene can be quenched by not only oxygen but also many other molecules, such as nitrobenzene and nitro-explosives. − These drawbacks limit the applications of pyrene-based sensors in many environments/situations such as (car) exhaust gases, wind tunnels, heat-vapors sterilization procedures, and wastewater treatment of explosives …”