Photophysical study of [Ru(2,2′-bipyridine)3]2+ and [Ru(1,10-phenanthroline)3]2+ encapsulated in the Uio-66-NH2 metal organic framework

Confinement of Luminescent Guests in Metal–Organic Frameworks: Understanding Pathways from Synthesis and Multimodal Characterization to Potential Applications of LG@MOF Systems

“…Similarly, the confinement of the metal complex ZnQ in the OX-1 MOF structure, enhances the luminescence quantum yield (from Φ = 35% in DMF suspension to 44% in the MOF) and extends the lifetime of the fluorophore . Another typical example of confinement effect has been described for the metal–organic complex Ru­(II)­tris­(2,2′-bipyridine) (Rubpy) after its encapsulation into different MOFs. − In all these examples, the caging of the Rubpy by the MOF host prevents its expansion, increasing the energy barrier to populate the 3 LF state, suppressing the major nonradiative deactivation pathway, and therefore, resulting in a rise of the emission lifetime. − This confinement effect has also been reported for Cu nanoclusters incarcerated into ZIF-8, where it was observed a 20-fold increase of the luminescence quantum yield (from 0.5% to 11%) accompanied by a substantial rise of emission lifetime (from 1.3 to 11 μs) . Surprisingly, the role of the confinement effect has been neglected in many other reports, where the increment of the emission lifetime of the encapsulated guests is solely attributed to an energy transfer process, while it was not considered as a possibility that the guest entrapment or caging phenomenon may contribute even more importantly to the rise of the emission lifetime value. ,,, …”

Modulation of Osmium(II) Tris(2,2′-bipyridine) Photophysics through Encapsulation within Zinc(II) Trimesic Acid Metal Organic Frameworks

“…The encapsulation of ruthenium­(II) polyimines has been reported for a variety MOF frameworks including HKUST-1­(Zn), USF-2, Uio-66, Uio-67, oxalate polymers, and RuBpy templated frameworks RWLC-1, -2, -3, and -5. − Encapsulation of the ruthenium complexes within MOF materials generally results in increased excited state lifetimes and shifted emission spectra that are attributed to confinement that restricts population of a nonradiative triplet ligand field state (LF) and solvent reorganization in response to the large excited state dipole of the 3 MLCT state. Ruthenium­(II) polypyridyls have also been encapsulated in zirconium phosphate matrixes, Zeolite-Y, and sol–gels all exhibiting similar photophysical features as RuBpy encapsulated MOFs. , …”