Recently, it has emerged a great interest on organic materials displaying room temperature phosphorescence. Within this family, the hexathiobenzene chromophore is not phosphorescent in fluid solution and becomes highly phosphorescent upon crystallization or rigidification of the matrix. We thus investigated this chromophore for sensing applications. First of all, the hexathipbenzene chromophore can be used as oxygen sensor since its phosphorescence is quenched by the presence of oxygen. The chromophore can also be modified by appending six terpyridine units at its periphery: as expected the supramolecular system is non-emissive in solution, but displays a green phosphorescence emission in the solid state due to the restriction of intermolecular motion in the solid state.Upon addition of Mg2+ to an air-equilibrated THF solution of the hexaterpyridine ligand, a supramolecular polymer is formed, in which a polymeric structure is formed in which a Mg2+ ion is coordinated by two terpyridine units of two different molecules. The reduced mobility of the organic moiety in the polymeric structure is reflected by the appearance of a bright phosphorescence (Φ = 0.10, τ = 5.3 µs) with band shape very similar to that of the ligand in the solid state. The light-harvesting polymeric antenna can be disassembled upon fluoride ions addition, thereby switching off luminescence and offering a new tool for fluoride ion sensing.

Phosphorescent chromophores as sensors of metal ions and oxygen

256th National Meeting (2018)

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