Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- 2017 (2) (entfernen)
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A set of highly fluorescent, pH-responsive boron dipyrromethene dyes covering the pH range of 5-12 is presented for broad range pH measurements in mixed aqueous-organic median and polymer matrices. Readout in the intensity Domain with low cost and miniaturized Instrumentation utilizes reversible protonation induced switching ON of their initially completely quenched flourescence mediated by photoinduced electron Transfer. All dyes, rationally designed to reveal closely matching Absorption and Emission properties, are accessible via facile two-step reactions in Overall yields of up to 20%. By modifying the Substitution pattern of the meso-Aryl substiuent, the pKa values could be fine-tuned from 6 to 11. Integration of these molecules into polymeric films by a simple mixing procedure yielded reversible and longterm stable pH sensors for naked eye detection.
Ternary semiconductors Quantum Dots (t-QDs) like AgInS (AIS) QDs are interesting alternatives to Cd-based QDs for applications as optical active materials in light-emitting diodes (LEDs), solar concentrators and solar cells as well as as biodiagnostic tools, respectively.
AIS QDs exhibit broad photoluminescence (PL) spectra in the visible and near infrared, which are tunable by size and chemical composition (ratio of components or doping).
In order to enhance the PL quantum yield (PL QY or Fpl) and prevent material deterioration and oxidation, these QDs are covered by ZnS shell. Here we show a spectroscopic study of differently colored AIS QDs synthesized in water, evaluating their PL properties, their PL QY and their PL decay.
The simple aqueous synthesis that avoids further ligand exchange steps for bioanalytical applications, the tunable emission color, the high PL QY, the high absorption coefficients and the long lifetime make these t-QDs promising Cd-free materials as biodiagnostic tools or optical active materials.