syn-(Me,Me)bimane: A Fluoroscent Ligand for Biologically Important Alkali and Alkaline Earth Metal Cations

syn-Bimanes have been used in biological systems as fluorescent-labeling agents for various biomolecules (e.g., proteins, amino acids, glutathione), due to their non-toxicity, low molecular weight and strong fluorescence. We have recently shown that one of these heterobicyclic compounds, syn-(Me,Me)bimane, coordinates Pd(II) in a chelating fashion through its two carbonyl oxygens.^[1] This was the first reported case of metal-bimane coordination, to the best of our knowledge.

We have since expanded our investigations to examine the coordination chemistry of syn-(Me,Me)bimane with different biologically important alkali and alkaline earth metal cations (e.g., Na⁺, K⁺ Li⁺, Ca²⁺, Mg²⁺).

Our study reveals that syn-(Me,Me)bimane exhibits several binding modes. The strongly fluorescent syn-(Me,Me)bimane binds M⁺ and M²⁺ cations via its carbonyl oxygens, leading to changes in its fluorescent properties. Spectroscopic evidence (NMR, UV-Vis, fluorescence) demonstrates that bimane coordination is reversible in solution.

The syntheses of these metal-bimane complexes, as well as their spectroscopic and crystallographic data, will be presented.

1. Das, P. J.; Diskin-Posner, Y.; Firer, M.; Montag, M.; Grynszpan, F., Dalton Trans. 2016, 45, 17123-17131