Turn-on and blue-shift fluorescence sensor toward L-histidine based on stable Cd metal-organic framework with tetranuclear cluster units.

A novel Cd-based two-fold interpenetrated metal-organic framework (MOF), namely {[Cd(BTDB)(4,4-bpy)]·DMF} (JXUST-14), (H2BTDB = 4,4'-(benzo[][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid and 4,4-bpy = 4,4-bipyridine), has been prepared and characterized. Single-crystal structure determination reveals that JXUST-14 has a tetranuclear cluster based 6-connected topological network with Schlafli symbol {4·6}. When soaked in common organic solvents and aqueous solutions with diverse pH values of 2-12 for 48 h, JXUST-14 remains stable. JXUST-14 is a highly selective and sensitive luminescent sensor for L-histidine (His) with a detection limit of 11.1 ppm. JXUST-14 is the first Cd-based MOF for the detection of His turn-on and fluorescence blue-shift effects. Experimental study and theoretical calculation suggest that the sensing process can be mainly attributed to a charge transfer and energy transfer mechanism. More interestingly, LED lamps of JXUST-14 and JXUST-14@His were successfully developed, which endowed efficient sensitivity for His detection and thus provide great potential for future applications.