The interest in organic chromophores is driven by their utility toward the manufacture of cheap and efficient electronic devices. Most organic chromophores are highly emissive in solution but become non-emissive in the solid state due to aggregation-caused quenching. Some chromophores, however, display the opposite effect: they show no emission in dilute solutions but are brightly fluorescent upon concentration. This phenomenon of aggregation-induced emission (AIE) is characteristic of molecules which emission manifold involves orbitals on fast rotating groups. We have shown that coordinative immobilization of functionalized tetraphenylethylene within metal-organic frameworks (MOFs) turns on fluorescence in the non-emissive tetraphenylethylene core. Despite the large interchromophore distances imposed by coordination to metal ions, a carboxylate analogue of tetraphenylethylene inside MOFs shows fluorescence lifetimes in line with those of molecular aggregates. As shown by 2H NMR studies, the dynamics of an AIE-type molecule can be controlled through coordination to metal ions in a porous framework.

Turn-on sensors based on framework-trapped molecular rotors

245th National Meeting (2013)

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