Dr Mike Coogan - BSc PhD MRSC CChem
Research Interests
The groups research areas are mainly based around organometallics, coordination chemistry, fluorescence cell imaging and esoteric aspects of chirality. Current research projects on organometallics involve applications of rhenium carbonyl bisimine complexes in biological imaging, and structural and synthetic studies.
fac-Rhenium tricarbonyl bisimine complexes in biological imaging
Luminescent d6 transition metal complexes have often been proposed as useful fluorophores for cell imaging due to their attractive photophysical attributes, but until very recently their actual applications have been scarce, and largely limited to ruthenium complexes in DNA and oxygen sensing. In the last few years, however, there has been an increasing number of reports of the design and application in cellular studies of a diverse range of Ir, Re and Ru complexes tailormade for imaging applications. This group has been at the forefront of the development of the use of rhenium fac-tricarbonyl polypyridyls as lumophores for this purpose. Typically these species have, by comparison to organic fluorophores, large Stokes shifts (hundreds of nm), long luminescence lifetimes (100 ns to ms), and enhanced photostability (lower photobleaching) due to the 3MLCT nature of their luminescence. By using a range of synthetic approaches to vary the charge, lipophilicity, polarity and reactivity of rhenium complexes we have developed agents which are taken up well by a variety of cells and can specifically target different cellular regions, e.g. mitochondria, nucleoli, membranes. More recently we have started to develop Ir and Ru species for similar applications.
Molecular vessels and structures.
By applying the ‘complex as ligand’ approach and taking advantage of the intrinsic geometrical preferences of various stable transition metal organometallic fragments we have successfully developed a range of trimeric vessels and cages based around transition metal polypyridyl systems. In the cases in which these are based around luminescent polypyridyl complexes, in addition to the intrinsic academic and aesthetic appeal of these structures there is the possibility to apply them as luminescent sensors in host-guest chemistry. This has been realized in the case of a trimeric rhenium terpyridine species which forms a luminescent vessel which can capture a silver ion, and signal its presence with a modulation of luminescence.
