Syntheses, crystal structures and thermal decomposition studies of two novel Mn(ii)-MOFs with tetrazole-based carboxylic acids

Abstract

The tetrazole-based carboxylic acids can be used as difunctionalized ligands for the preparation of functional MOFs with novel topologies. Herein we chose two tetrazole-based carboxylic acids, 1,3-bis(2-carboxymethyltetrazol-5-yl)benzene (H₂L¹) and 2-(5-(3-pyridyl)tetrazol-2-yl)propionic acid (HL²), as ligands and synthesized two novel Mn(II)-MOFs: [Mn(L¹)(DMF)(H₂O)]·0.375H₂O (1) and [Mn(L²)₂] (2) (DMF = N,N-dimethylformamide). These MOFs have been characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. MOF 1 displays a 2D network with an sql topology, while MOF 2 shows a novel binodal 5,6-connected 3D framework with the Schläfli symbol of (3²·4⁴·6⁴)(3⁴·4⁶·6⁴·7). Differential scanning calorimetry and thermogravimetric analyses were adopted to investigate the thermal decomposition processes of the MOFs and the thermodynamic parameters (ΔH, ΔS and ΔG) were obtained.