The 3D porous metal–organic frameworks based on bis(pyrazinyl)–trizole: structures, photoluminescence and gas adsorption properties

Abstract

Two novel 3D porous metal–organic frameworks, {[Zn₂(bpt)(btc)]·4H₂O}_n (1) and {[Cd₂(bpt)(btc)(H₂O)]·(DMA)₂}_n (2) (DMA = N,N-dimethylacetamide), were prepared based on 3,5-bis(pyrazinyl)-1,2,4-trizole (Hbpt) with the auxiliary ligand 1,3,5-benzenetricarboxylic acid (H₃btc). Complex 1 could be described as a (3,6)-connected binodal 3D network with rutile topology and Schläfli symbol of (4.6²)₂(4².6¹⁰.8³), where its coordination framework exhibits a high thermal stability up to 420 °C as well as excellent boiling-water resistance. Complex 2 shows a (3,6,8)-connected trinodal 3D framework with a Schläfli symbol of (4.6²)₂(4¹⁴.6¹².8²)(4⁴.6¹⁰.8), which has not been reported previously. Interestingly, the gas-adsorption investigation discloses that complex 1 possesses a high enthalpy of H₂ adsorption (9.6 kJ mol⁻¹). Intensive solid-state fluorescence spectra of complexes 1 and 2 have also been determined.