Selective CO₂ uptake in a bi-pillared layer 3D metal-organic framework of Zn(II)

Abstract

A new two-fold interpenetrated 3D bi-pillared framework, {[Zn(1,4-bdc)(azbpy)]?DMF}_n (1), where 1,4-bdc = 1,4-benzene dicarboxylic acid, azbpy = 4,4′-azobipyridine and DMF = N,N-dimethyl formamide, has been synthesized from a mixed ligand system and characterized by single crystal as well as powder X-ray diffraction and thermogravimetric analysis. The metal center, Zn(II), having a trigonal bi-pyramidal geometry, is connected to the three different 1,4-bdc linkers in the equatorial positions while the axial positions are occupied by the two different 4,4?-azbpy pillars. The framework contains one-dimensional rectangular shaped channels along the c axis and the channel surfaces are decorated with the nitrogen atoms of -N=N-functional group from azbpy ligand. The desolvated framework has a specific surface area of ∼ 40 m²g^-1 and shows excellent selective uptake of CO₂ at 195 K among other small gases like Ar, N₂ and H₂. (1) also adsorbs acetonitrile and benzene solvent vapors at 298 K.