Structure and characterisation of a novel 3-D Ba(II)-MOF based on the {Ba4O7} core

A novel three-dimensional barium metal-organic framework [Ba 3 (btc) 2 (H 2 O) 4 ].0.5H 2 O (H 3 btc = 1,3,5-benzenetricarboxylic acid) has been synthesised under hydrothermal conditions, and characterised by single-crystal X-ray structure determination, thermogravimetric analysis, X-ray powder diffraction, IR, and photoluminescence studies. The volume of the tunnel formed by the two-dimensional layers is 341.9 A 3 per unit cell using PLATON based on the crystal structures, comprising 14.3% of the crystal volume 2387.2 A 3 . The solid-state fluorescence measurement of this compound at room temperature reveals a fluorescent emission band at 454.5 nm under the excitation of 337 nm, assigned to a charge-transfer transition.