Simple perylene dyes, which are known for their high extinction coefficients, are converted into intense and highly fluorescent (at ca. 540 nm) dyes such as 1 by a directed chromophore-chromophore coupling. Molar extinction coefficients of more than 400 000 L mol cm are attained. R = CH(C H ) , CH(C H ) , CH(C H ) .
Aldehydes are usually determined via chemical derivatization using a chromogenic and fluorogenic reagent followed by chromatographic separation and UV-visible detection. As a consequence, continuous on-line monitoring is impossible. Following our concept of reversible chemical reactions as the basis of optical sensors, we have investigated N-amino-N'-(1-hexylheptyl)perylene-3,4:9,10-tetracarboxylbisimide for aldehyde sensing. The fluorogenic reactand has been embedded in plasticized PVC, and the resulting thin layers have been exposed to aqueous samples of aliphatic aldehydes and ketones. The reactand exhibits a pronounced increase in fluorescence upon interaction with aldehydes since the chemical reaction causes a dequenching of perylene fluorescence. Upon interaction with aqueous propionaldehyde, sensor layers typically exhibit a dynamic range from 5 to 100 mM propionaldehyde, and the limit of detection amounts to 0.08 mM. The forward and reverse response time (t95) for a decade change in activity is in the range of 2-7 min, when measured at pH 2.5. The selectivity of sensor layers toward aldehydes correlates with their lipophilicity in that aldehydes with higher lipophilicity are more efficiently extracted into the polymer layer.
Fluorescent hydrazones are afforded by the reaction of the nonfluorescent N-aminoperylene-3,4:9,10-tetracarboxylic-bisimides with ketones and aldehydes; thus we obtain a fluorescent derivatization for the qualitative and semiquantitative determination of carbonyl compounds.
Communications
ExperimentalThe synthesis and purification of bis(dimethylglyoximato)platinum(II) (Pt(dmg) 2 ) has been reported elsewhere [12]. The metal complex was deposited on a cleaved KBr(001) substrate under 4´10 ±7 mbar of residual gas using an organic molecular beam deposition apparatus [29]. The thickness of the evaporated films was controlled by regulating the distance between the substrates and the Knudsen cell in which the metal complex was held. The evaporation temperature was ca. 200 C, and the substrate was kept at room temperature during deposition. The topographic images from atomic force microscopy (AFM) of the evaporated films were measured in air by a Seiko SP-3700 in contact mode. The transmission electron diffraction was taken by a Zeiss CEM-902 with an accelerating voltage of 80 kV. The observed film was stripped from the KBr substrate by immersion in water after being reinforced with an amorphous carbon coating. XRD measurements of the evaporated film on a KBr substrate were performed on a Mac Science MXP-18 diffractometer with Cu Ka radiation source (1.5405 ). Reflections were recorded over a 2y range from 6 to 60.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.