Thermal and Gas Dual-Responsive Behaviors of an Expanded UiO-66-Type Porous Coordination Polymer

摘要

Through a modified solvothermal reaction using benzoic acid as an additive, the fcu-type framework [Zr6O4(OH)(4)(edba)(6)] (H(2)edba=4,4'-(ethyne-1,2-diyl)dibenzoic acid), an expanded version of UiO-66, is synthesized as high-quality single crystals, which can retain their single-crystallinity after solvent exchange and degas treatments. In situ variable-temperature single-crystal X-ray diffraction measurements show that the guest-free framework exhibits a remarkably large isotropic negative thermal expansion (alpha=-11.0 x 10(-6) K-1) as a result of the transverse vibrational bending of the long organic ligand. By virtue of the relatively large p-conjugation system of the organic ligand, [Zr6O4(OH)(4)(edba)(6)] also exhibits bright blue luminescence, which can be quenched efficiently by gaseous O-2 (K-sv=2.4 bar(-1)).