Filtern
Erscheinungsjahr
- 2017 (2) (entfernen)
Dokumenttyp
Sprache
- Englisch (2)
Referierte Publikation
- ja (2) (entfernen)
Schlagworte
- Smartphone (2) (entfernen)
The fluorescence properties of three molecular rotors, related to 4-dimethylamino-4-nitrostilbene (4-DNS), are studied versus different diesel/kerosene blends. In nonviscous solvents, these compounds can populate a twisted intramolecular charge transfer state which deactivates nonradiatively, successfully suppressing fluorescence emission. Solution experiments with diesel/kerosene blends showed a good linear correlation between the fluorescence intensity of the probe molecules and the diesel fraction of the blend. The dyes have been immobilized on paper, retaining their fluorescence behavior, i.e., negligible emission in the presence of nonviscous organic solvents and increasing fluorescence when the environment is increasingly viscous. When the impregnated paper is devised as a test strip, the latter is compatible with a newly designed smartphone reader system, which allows in-the-field measurements. The method can safely detect the presence of kerosene in diesel at ≥7%, which competes favorably with current standard methods for the detection of diesel adulteration.
In this work, a family of pH-responsive fluorescent probes has been designed in a rational manner with the aid of quantum chemistry tools, covering the entire pH range from 0−14. Relying on the boron−dipyrromethene (BODIPY) core, all the probes as well as selected reference dyes display very similar spectroscopic properties with ON−OFF fluorescence switching responses, facilitating optical readout in simple devices used for detection and analysis. Embedding of the probes and reference dyes into hydrogel spots on a plastic strip yielded a test strip that reversibly indicates pH with a considerably small uncertainty of ~0.1 pH units. These strips are not only reusable but, combined with a 3D-printed case that can be attached to a smartphone, the USB port of which drives the integrated LED used for excitation, allows for autonomous operation in on-site or in-the-field applications; the developed Android application software (“app”) further simplifies operation for unskilled users.