Three Robust Blue-Emitting Anionic Metal-Organic Frameworks with High Stability and Good Proton Conductivities

Three anionic luminescent metal-organic frame-works (LMOFs; [M(tcbpe)(CH3)(2)NH2]center dot H2O; M = In3+, Eu3+, Gd3+; tcbpe = 4',4''',4''' '',4''' ''' '-(ethene-1,1,2,2-tetrayl)tetrakis-[(1,1'-biphenyl)-4-carboxylic acid]) are synthesized by employing the tetraphenylethene core ligand H-4 tcbpe with M3+ ions. They stack in the similarly 4-fold-interpenetrated three-dimensional porous structure. All give blue emission when excited at 365 nm, with fluorescence quantum yields of 34.8% (MOF-In), 7.1% (MOF-Eu), and 28.1% (MOF-Gd). Somewhat surprisingly, these three complexes are extremely stable both in various solvents and across a broad pH range: MOF-In is stable between pH = 0 and 14, and MOF-Eu and MOF-Gd are stable between pH = 0 and 13. Additionally, they also show good proton conductivities of 2.29 X 10(-5) S.cm(-1) (MOF-In), 2.02 X 10(-4)S.cm(-1) (MOF-Eu), and 1.24 X 10(-4) S.cm(-1) MOF-Gd at high temperature under 98% relative humidity. To the best of our knowledge, this is the first reported LMOF series combining aggregation-induced emission behavior with good proton conductivities.

Automated summary

This study presents a novel series of anionic luminescent metal-organic frameworks with high fluorescence quantum yields and good proton conductivities, showing stable properties in various solvents and across a broad pH range.