A color changing sensor for the pollutant perfluorooctanoic acid was developed. The pollutant was visually detected from soil at concentrations as low as 3 ppm.
Schiff base imine condensations are a useful tool for macrocycle synthesis and applications within supramolecular chemistry. Here we address the mixtures of products that can arise from template free synthesis using dicarbonylheterocycles and diamines, and look to develop metal-free template methods for selective macrocycle formation. A range of alkyl α,ω-diamines were combined with phenanthroline and pyridine heterocyclic dicarbaldehydes under standard literature conditions. The reaction conditions were modified to demonstrate a relationship between choice of solvent and product equilibria. It was observed that benzene and toluene could shift a mixture of products and unreacted starting materials to form predominantly one imine product for a number of systems. Once the macrocyclic products had been characterized in selected solvents, iodinated halogen bonding guest molecules were added to direct macrocycle assemblies using non-covalent interactions. Studies to investigate host – guest suitability and halogen bond interactions were conducted, and it was found that tetraiodoethylene had an influence on the formation of a phenanthroline based macrocycle. Proof of concept experiments were performed to show the influence of the guest molecule, tetraiodoethylene, on the macrocyclic products formed under competitive dynamic combinatorial chemistry conditions.
X-ray crystallographic analysis of mono- and di- 2-bromoimidazolium cations as salts with bromide, hexafluorophosphate, or as double salts of the two, have indicated a tendency for disorder around the imidazolium...
Perfluorinated carboxylic acids (PFCAs) are widespread, potentially harmful, and difficult to detect pollutants. Here we investigate the use of three colorimetric porphyrin host molecules with chain lengths derived from different PFCA precursors as visual sensors for a range of different sized perfluorocarboxylates. We found that modifications to the length of the fluorinated chains led to subtleties in binding preferences and the resultant colorimetric (RGB) response. Host-guest interactions were investigated with UV-visible spectroscopy, and ImageJ software analysis was used to relate RGB information from digital photographs with binding and perceived colors. The CIE76 formula for color difference was used for the visual estimation of PFCA concentrations from generated color charts. Color responses were also parameterized to generate calibration curves from known concentrations of perfluorooctanoic acid so that total PFCA concentrations could be estimated with less than 20% error using a phone camera across a 10 ppb (parts per billion) – 16 ppm (parts per million) range.
Perfluorinated carboxylic acids (PFCAs) are widespread, potentially harmful, and difficult to detect pollutants. Here we investigate the use of three colorimetric porphyrin host molecules with chain lengths derived from different PFCA precursors as visual sensors for a range of different sized perfluorocarboxylates. We found that modifications to the length of the fluorinated chains led to subtleties in binding preferences and the resultant colorimetric (RGB) response. Host-guest interactions were investigated with UV-visible spectroscopy, and ImageJ software analysis was used to relate RGB information from digital photographs with binding and perceived colors. The CIE76 formula for color difference was used for the visual estimation of PFCA concentrations from generated color charts. Color responses were also parameterized to generate calibration curves from known concentrations of perfluorooctanoic acid so that total PFCA concentrations could be estimated with less than 20% error using a phone camera across a 10 ppb (parts per billion) – 16 ppm (parts per million) range.
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