A Molecular System for Controlled Release of Iron Developed
Researchers integrated ferrocene (Fe-containing molecular sandwich) with carbon nanohoops to create a system releasing Fe2+ ions when activated by green light.
In an international cooperation, researchers at the Universities of Amsterdam and Zurich have developed a molecular system for controlled release of iron. They integrated ferrocene, a molecular sandwich that encloses an iron atom, with a carbon ‘nanohoop’. As a result, the system allows for the release of Fe2+ ions upon activation with benign green light.
It has recently been presented in a paper in the Journal of the American Chemical Society (“Strain-Induced Photochemical Opening of Ferrocene[6]cycloparaphenylene: Uncaging of Fe2+ with Green Light”).
The research was carried out by the groups of Dr Tomáš Šolomek at the University of Amsterdam’s Van ‘t Hoff Institute for Molecular Sciences and Dr Peter Štacko at the University of Zurich (Department of Chemistry). Their expertise is in photo cages, molecular photochemical tools that offer precise control over substrate activity in time and space using light as a bio-orthogonal stimulus. Photo cages permit activation of biologically significant molecules such as proteins, nucleotides, or drugs. Not only are they a great tool to study mechanisms and dynamics of biochemical processes, they also have potential for therapeutic applications such as photo activated chemotherapy.
In the research now published in JACS, the researchers shifted their focus from controlling the activity of organic molecules to another crucial component in many biological systems: iron. Renowned for its role in oxygen transport in the human body, it also has a pivotal role in the energy-providing redox processes in mitochondria, in the synthesis of deoxyribonucleotides, or in protecting cells from oxidative stress.
Strain-induced photo release
Nature has developed a protein-based system to tightly regulate iron’s uptake and balance. In their paper, the researchers present a less sophisticated yet fully functional synthetic equivalent that stores iron and releases it ‘on demand’.
The system is based upon the use of ferrocene as the iron carrier, and enables controlling its function by integrating it into a carbon nanohoop. Ferrocene is an organ metallic ‘sandwich complex’ that tightly holds an iron atom between two cyclopentadienyl rings. On itself, it is chemically rock stable and resistant to light. Incorporating it into a molecular nanohoop, however, changes this. When the two cyclopentadienyl rings are connected by means of six coupled benzene rings (a cycloparaphenylene nanohoop), a system emerges that enables control over the iron containment. Although conformationally stable, the integration twists the entire nanohoop structure and exerts a large mechanical stress on the ferrocene. As a result, the system becomes susceptible to irradiation with green light, which results in release of the iron.
In their paper, the researchers describe how the iron can be released with high efficiency upon irradiation. They expect this strategy of introducing mechanical stress in molecules to offer great promise also beyond the realm of photo cages. For instance, it can potentially enable the development of new responsive materials in supramolecular, organ metallic, or polymer chemistry.
Source: University of Amsterdam
