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

Abstract

Three metal–organic frameworks based on trinuclear building blocks, isomeric α-{[NH₂(CH₃)₂]₂[Zn₃(FDA)₄]·2DMF}_n (1) and β-{[NH₂(CH₃)₂]₂[Zn₃(FDA)₄]·2DMF}_n (2), as well as {[NH₂(CH₃)₂][Zn₃(FDA)₂(μ₂-OH)₂(μ₃-OH)]·1.03H₂O}_n (3) (H₂FDA = 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(3⁴·4⁴·5²·6⁶·7¹⁰·8²). The photoluminescence spectra of 1–3 are reported for the first time, and all the Zn(II) complexes emit blue luminescence.