Luminescent d(6) 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 tailor-made for imaging applications. The design principles, uptake and cellular localisation of this new class of imaging agents are presented in context in this feature article.

A series of lipophilic and hydrophilic fac tricarbonyl rhenium bisimine complexes have been prepared, their membrane-permeabilities explored in liposomes and their potential for application in fluorescence microscopy cell imaging demonstrated in the first application of MLCT-fluorescent rhenium complexes in cell imaging.

No abstract

No abstract

The synthesis of a series of rhenium fac tricarbonyl bisimine complexes and their application as lumophores in fluorescence imaging of yeast and human adenocarcinoma cells is reported. A wide range of complexes are synthesised with varying charges and lipophilicities, all of which have photophysical properties which make them suitable as cell imaging agents. After attempts to apply these as imaging agents in various strains of yeast which showed limited uptake, an investigation was undertaken of their applications as imaging agents in mammalian cells. In general the uptake was high and short-term toxicity and photobleaching appear to be low. The patterns of uptake and localisation are correlated with structural and electronic features of the complexes in an attempt to establish ground-rules for the design and application of rhenium complexes in imaging of eukaryotes.