Synthesis and structural investigation of two metal-organic frameworks constructed from alkaline earth metal cations and organic ligand 5-nitroisophthalic acid (5-NO2-H2BDC)

Two supermolecular co-ordination polymers [M(5-NO₂-BDC)(H₂O)₆] [M = Sr(1), Ba(2)] were prepared by the assembly of alkaline earth metal cations and symmetric organic ligand 5-NO₂-H₂BDC, respectively. These two complexes have been characterized with the aid of elemental analysis, thermal analysis, infrared spectroscopic and X-ray crystallography. Both 1 and 2 have a similar 3D flowerlike supramolecular assembled by multiple interpenetration of the 1D chains where 12-membered rings share common C–O–M edges with each other extended by O–H···O hydrogen bonds. The co-ordination geometry around M (II) ions could be described as distorted tricapped trigonal prism arrangements.