Bifunctional transition metal complexes as nucleic acid photoprobes and photoreagents

Transition metal complexes that bind to DNA have been the focus of extensive research aimed at increasing the understanding of genetic information processing and at developing ways to interfere with these mechanisms. Beside the continuous development of “dark reacting” artificial metallonucleases and metal-based chemotherapeutics such as cisplatin, photo-active octahedral metal complexes have been successfully used as DNA luminescent probes and light-driven reactive agents during the last decades. A recent emerging trend to improve their potential as molecular tools for studies of the genetic material is the design of bifunctional assemblies where the photo-active metal center is tethered through a flexible linker to a nucleic acid recognition or reactive moiety. This mini-review highlights some recent progresses in developing such bifunctional complexes through derivatization strategies ranging from the design of dimeric complexes and chromophore-quencher systems to the development of biotin–metal complex conjugates for avidin-mediated detection of biomolecules.