New Interpenetrated Copper Coordination Polymer Frameworks having Porous Properties

Two new 3-fold inter-penetrated 3D microporous metal-organic coordination polymers (MOCPs) of Cu(II), [Cu-3(blpy)(1.5)(2,6-ndc)(3)](n) (1) and {[Cu(bpe)0.5(2,6-ndc)]center dot 0.5H(2)O}(n) (2) (bipy = 4,4'-bipyridine; bpe 1,2-bis(4-pyridyl)ethane; and 2,6-ndc = 2,6-naphthalenedicarboxylate), have been synthesized using a mixed-ligand system and Structurally characterized by single-crystal X-ray diffraction study. Room-temperature reaction of Cu(II) with bipy and 2,6-ndc affords 1, whereas reaction with bpe and 2,6-ndc yields 2. Structure determination reveals that in both cases, a 2D square grid made by Cu(II) and 2,6-ndc with the aid Of Cu-2(CO2)(4) paddlewheel building block is connected by bipy (1) or bpe (2) organic pillar results 3D alpha-polonium type frameworks. Framework I is rigid and robust without any guest molecules, whereas 2 is flexible, realized by the guest induced structural transformations. Both the frameworks show high thermal stability. Framework I and dehydrated form of 2, i.e 2'contains 16.6% and 21.4% void space, respectively and Langmuir surface area calculated from nitrogen adsorption study for 1 and 2' is 113.0 and 337.5 m(2)/g, respectively. Both the frameworks can store approximately 1 wt% of molecular hydrogen at 77 K and 15 bar, in particular, the density of adsorbed hydrogen in 1 is one of the highest reported so far in porous MOCPS. Compounds 1 and 2' can also store 11.0 and 13.2 wt % carbon dioxide at 195 K.