Two Terbium Metal-Organic Frameworks Showing Fluorescence Sensing and Proton Conductivity

Two new terbium-based metal-organic frameworks, {[Tb(ADBA)(CH3COO)(H2O)]<middle dot>H2O}(n) (<bold>MOF 1</bold>) and [Tb(ADBA)(HCOO)(DMF)](n) (<bold>MOF 2</bold>) (H(2)ADBA = 4,4 '-(9,10-anthracenediyl) benzoic acid), were synthesized by the solvothermal method. Structural analysis indicates that the Tb-III ions in <bold>MOFs 1</bold> and <bold>2</bold> are coordinated to acetic and formic acids, respectively, leading to differences in the structures. Fluorescence measurements show that both <bold>MOFs 1</bold> and <bold>2</bold> are fluorescence sensors for Al3+ and Ga3+ with fluorescence enhancement and a blue shift. The detection limits of <bold>MOF 1</bold> are 0.067 mu M for Al3+ and 0.093 mu M for Ga3+, and the detection limits of <bold>MOF 2</bold> are 0.064 for Al3+ and 0.086 mu M for Ga3+. The proton conductivity measurements of <bold>MOFs 1</bold> and <bold>2</bold> indicate that the proton conductivities of <bold>MOFs 1</bold> and <bold>2</bold> increase in resistance with increasing humidity. <bold>MOF 1</bold> is more sensitive to humidity with a maximum conductivity of 1.07 x 10(-5) S<middle dot>cm(-1) under 40 degrees C and 98% RH. Therefore, <bold>MOFs 1</bold> and <bold>2</bold> are potential multifunctional MOF materials.