Three luminescent metal-organic frameworks constructed from trinuclear zinc(II) clusters and furan-2,5-dicarboxylate

Three metal-organic frameworks based on trinuclear building blocks, isomeric alpha-{[NH2(CH3)(2)](2)[Zn-3(FDA)(4)]center dot 2DMF}(n) (1) and beta-{[NH2(CH3)(2)](2)[Zn-3(FDA)(4)]center dot 2DMF}(n) (2), as well as {[NH2(CH3)(2)][Zn-3(FDA)(2)(mu(2)-OH)(2)(mu(3)-OH)]center dot 1.03H(2)O}(n) (3) (H(2)FDA = furan-2,5-dicarboxylic acid), have been obtained under solvothermal conditions by adjusting the anions of zinc salts and solvents. These compounds are characterized by single-crystal X-ray diffraction, thermogravimetric analysis and luminescence measurements. The building blocks of the three MOFs are trinuclear clusters stabilized by carboxylic groups, and the resulting three-dimensional frameworks are differentiated by the structural nature of the secondary building units (SBU). MOFs 1 and 2 display pcu and bcu nets, respectively. MOF 3 exhibits a new topology, which is a 3,8-connected net with the point symbol of (3.4.5)(2)(3(4).4(4).5(2).6(6).7(10).8(2)). The photoluminescence spectra of 1-3 are reported for the first time, and all the Zn(II) complexes emit blue luminescence.