Skip to main content

Rational design of long-wavelength chromo- and fluorogenic chemosensors and composite materials for ionic analytes

Final Activity Report Summary - LOWCHEMOSMAT (Rational design of long-wavelength chromo- and fluorogenic chemosensors and composite materials for ionic analytes)

In optical sensing of chemical species, the performance of a sensor strongly depends on selectivity, sensitivity and the suitability of the wavelength range of communication. Fluorescence methods are very sensitive. However, in many environmental and biochemical applications the matrix can auto-fluoresce or absorb the light used for probing the sensor's response. Working in the red / near-infrared (NIR) region of the spectrum for optical sensing can improve the sensitivity of assays, since biological matrices are optically silent above 650 nm. These facts, together with the current availability of cheap excitation sources for the red region of the spectrum, have recently fuelled the development of red / NIR probes for different analytical applications.

In this project, a remarkable contribution to chemical, photophysical and mechanistical knowledge on new red/NIR fluorescent probes has been made. Several families of dyes have been investigated and characterized, and important and novel results have been achieved. For example, a series of highly emissive boron-dipyrromethene (BODIPY) dyes have been studied and successfully included in polymer nanoparticles, yielding highly emissive and photo / chemically stable beads for applications in fluorescence confocal microscopy or multiplexing. The new BODIPY dyes investigated include styryl-substituted and aromatic ring-fused BODIPYs (with phenantherene or dihydronaphthalene ring fusion) with quantum yields of fluorescence approaching 100 %.

Other remarkable results include the development of a rubyrin with ever-red shifted spectra, that has been applied as optode for Hg(II) detection in water when included in a polyurethane film, or expanded porphyrins core-modified with different heteroatoms. On the other hand, the synthesis of (hemi) cyanine dyes has also been explored and a meso-cyclam-substituted cyanine chromophore has been employed as NIR probe for the detection of the citrate anion following a displacement assay. Additionally, and in order to get some insight into the response mechanism of functional meso-substituted heptamethine cyanines, quantum mechanical calculations and photophysical studies with several model compounds were carried out.