Supplementary material from "Gas adsorption and structural diversity in a family of Cu(II) Pyridyl-isophthalate metal-organic framework materials"

A family of Cu(II)-based metal-organic frameworks (MOFs) has been synthesized using three pyridyl-isophthalate ligands, H₂L¹ (4'-(pyridin-4-yl)biphenyl-3,5-dicarboxylic acid), H₂L² (4''-(pyridin-4-yl)-1,1':4',1''-terphenyl-3,5-dicarboxylic acid) and H₂L³ (5-[4-(pyridin-4-yl)naphthalen-1-yl]benzene-1,3-dicarboxylic acid). Although in each case the pyridyl-isophthalate ligands adopt the same pseudo-octahedral [Cu₂(O₂CR)₄N₂] paddlewheel coordination modes, the resulting frameworks are structurally diverse, particularly in the case of the complex of Cu(II) with H₂L³, which leads to three distinct supramolecular isomers, each derived from Kagomé and square nets. In contrast to [Cu(L²)] and the isomers of [Cu(L³)], [Cu(L¹)] exhibits permanent porosity. Thus, the gas adsorption properties of [Cu(L¹)] were investigated with N₂, CO₂ and H₂, and the material exhibits an isosteric heat of adsorption competitive with leading MOF sorbents for CO₂. [Cu(L¹)] displays high H₂ adsorption, with the density in the pores approaching that of liquid H₂.