The Rybak-Akimova Group

Molecular Tweezers

One of the problems facing modern supramolecular chemistry is the design of selective receptors and reagents for bifunctional and polyfunctional organic substrates. These are essential for the effective design of enzyme mimics. Our work has involved the design, synthesis, and characterization of compounds that incorporate both a reactive center and a receptor center into saddle-shaped organic molecules, called "molecular tweezers." A veriety of modifications can be made; the macrocycle ring can be expanded from a flat 14-membered ring to a saddle-shapped 16-membered ring, for example. We are currently perfecting techniques to attach cyclam, cyclene, a variety of amino pyridines, and carboxylic acids to the periphery of Jager Platforms.
Two receptor sites attached to a folded scaffold are expected to selectively bind the substrate, which can then be released by regulated conformational changes in the scaffold. Saddle-shaped macrocyclic Jäger and cyclidene complexes have been explored by our group as platforms for molecular tweezers. Cyclidens are relatively conformationally flexible, thus allowing for switching between open and closed forms. Two receptor sites attached to a folded platform would pick and hold the substrate, which can then be released by regulated conformational changes in the platform. Also, it is possible to regulate the shape of the macrocycle through change in metal oxidation state and reversible axial coordination of bulky ligands to the fifth position of the metal. Different functional groups can be attached to the platform, allowing us to study host-guest interaction with different types of substrates. Currently, tweezers for dicarboxylates and tweezers for alkyl diammonium salts have been prepared and characterized. Immediate plans include expanding the range of the substrates, switching between binding and non-binding conformations of the tweezers, and exploring catalytic shape-selective redox reactions.

Cyclidene-Based Molecular Receptors

Coming soon!

Complexation Between Crown-Containing Ditopic Receptors And Diammonium Salts

Coming soon!