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nanotimes Reports

10-05/06 :: May/June 2010

Dr. rer. nat. K. Rurack (BAM Germany): Steady-State and Time-Resolved Spectroscopy of Ion-Sensitive Fluorescent Probes

Research Report 235, ISBN 3-89701-362-2 Abstract: http://www.bam.de/en/service/publikationen/publikationen_medien/fb235e.pdf

Full text: http://www.bam.de/en/service/publikationen/publikationen_medien/fb235e_vt.pdf

The present work is focused on the study of the spec- troscopic and complexometric behavior of different ion- sensitive fl uorescent probes. Three of the four types of probes studied follow a conventional prin- ciple of signal generation and their molecular consti- tution corresponds to either a fl uorescent ligand ( BP(OH)2), so-called intrinsic charge transfer (ICT) fluorescent probes (donor-acceptor-substituted chal- cones), or electron transfer (ET) fl uorescent probes (substituted triaryl-Δ2-pyrazolines).

The latter two systems are designed in a modular way and thus, both the signal generating fluorophore and the complexing receptor can be carefully tuned. Whereas in the case of the ICT probes both units are electronically conjugated, these moieties are more or less electronically decoupled in the ET probes and signal generation is based on the modification of a long range electron transfer process. The fourth type of probe investigated, a boron dipyrromethene

derivative (BDP), is also designed in a modular way. But here, due to the highly pretwisted constitution of the molecule, fluorophore and receptor are only “virtually” decoupled. Besides employing this alter- native mechanism of signal generation, control of the selectivity by carefully directed receptor design and improvement of the selectivity and sensitivity of fl uorometric metal ion analysis by recording time resolved emission spectra (TRES) were the main aims of these investigations.

Furthermore, with the aid of various model com- pounds, NMR spectroscopy as well as quantum chemical calculations, a fundamental understanding of the photophysical behavior of the different classes of dyes was obtained.