Research
Lanthanide coordination chemistry
Since 2011 we have been exploring the intricate that determines the structure and properties of lanthanide complexes. We are building tools to study lanthanide coordination chemistry focusing on optical spectroscopy and x-ray scattering. Understanding lanthanide coordination chemistry will allow us to address lanthanide metals as a resource and as functional materials in energy and health.
The development of equipment and of lanthanide coordination chemistry has come to a point, where it is prudent to revisit the fundamental aspects of lanthanide chemistry and photophysics. Kinetically stable lanthanide complexes can readily be made, even in conformationally locked forms. That is, the kinetically stable complexes allows for investigations, in which the speciation is known. All in all, the tools are at hand to instigate a step-change in our understanding of lanthanide solution phase chemistry. This is one of our long-term goals.
The association between lanthanide complexes and selected guests can be considered a set of alternative tools to study the conformation and structure of lanthanide complexes in solution. Tools, which themselves open interesting possibilities for applications as well as open windows into the conformational space of lanthanide complexes. The work of using lanthanide complexes as anions sensors, and to create large assemblies continues in the group of Professor Stephen Faulkner, while we work on projects towards more focused on understanding lanthanide self-assembly and use it as a tool to probe solution structure of lanthanide complexes.
Physical unclonable functions
'Anti-fake' and 'anti-counterfeiting' are often mentioned in papers on lanthanide luminescence in the solid state. We decided to investigate, and found that lanthanide luminescence may provide the means to develop next generation data encryption anti-counterfeiting systems. Random features or physical unclonable functions contain so much randomness that they are unique, and cannot be recreated. We are working on exploiting this randomness to make new solutions for encryption and anti-counterfeiting.
Dyes for bioimaging and bioassay
Fluorescence microscopy has revolutionized science by allowing visualization of micro- and nano-scopic structures, while fluorescence detection/spectroscopy has done the same for DNA sequencing, and enabled high throughput screening. The scope and at the same time the limitation on these fluorescence based techniques is primarily found in the dyes used to stain/label the studies systems. In commercial terms, the golden standard for traditional fluorescent dyes is set by a single patent filed by molecular probes (now Invitrogen), the patent describing the Alexa dyes. This patent covers the most extensive study, where dyes have had their physical chemical and photophysical behavior optimized, in order to be the best possible for biological and medical applications. We aim towards replicating this impressive effort for a new and unique group of fluorophores: the triangulenium dyes.
Responsive luminescent dyes
Considerable effort has been focused on the development of responsive probes able to exploit the affinity of mononuclear lanthanide complexes for anions such as phosphate, lactate and citrate, and such probes have been shown to be promising diagnostics for prostate cancer. Anion responsive molecules have been designed, synthesized and investigated vigorously for several decades. Receptors capable of binding anions selectively and strongly in organic solvents and solvent mixtures have been achieved, while anion binding in water remains a challenge.
Kinetically stable lanthanide complex based receptors have recently shown potential in the binding anions in aqueous solution. We aim to exploit multinuclear lanthanide complexes to create molecules that show a ratiometric to simple analytes such as DO and pH, while exploited organic dyes to make responsive systems for sensors and imaging.
Porous materials for optical sensors
Materials for sensing applications are important for monitoring production processes and investigating biological processes. Of the many analytes, which can be monitored, pH is still the most essential as it yields direct as well as indirect information as to the well-being of cells and the status of a production line. Fluorescence offers an ideal solution for detection and sensing, as addressing and reading out the probe is done by light. The probe can be read out using a microscopy, a spectrometer or through fiber optics. The latter, in combination with miniaturized light-sources and detectors allow for the construction of a robust fluorescence based fluorescence based pH sensor. Fabrication of a fluorescence-based sensor is not trivial. We work with dyes encapsulated in an ORMOSIL-matrices. We can routinely produce mesoporous materials for pH and DO sensors, and are working on developing macroporous materials for sensors that detect larger analytes.
Monitoring structural change
We work towards understanding the effect of exciting molecules with light for instance the structural signature of intramolecular vibrational redistribution (IVR) and vibrational cooling (VC). To do so we use time-resolved wide angle x-ray diffraction (TRWAXS).
The lanthanide ions have partially filled 4f-orbitals; which, among others interesting phenomena, result in complexes that can be probed with paramagnetic NMR, luminescence and chiroptical spectroscopy. Lanthanide complexes with cyclen derived ligands with acid or amide pendant arms are kinetically stable, and allow for creation of large lanthanide containing molecules as the speciation is simple—the lanthanide will always be in the binding pocket, but the conformational space available to these complexes is still large. We wish to determine the properties and dynamics of this conformational space.