Enhancement of H-2 Adsorption in Coordination Framework Materials by Use of Ligand Curvature

Solvothermal reaction of the ligands H4L110 ((2,7-phenanthrenediyl)diisoplithalic acid) and H4L111 ([2,7-(9,10-dihydrophenanthrenediyl)jdiisophthalic acid) with Cu(NO3)(2)center dot 2.5H(2)O in a slightly acidified mixture of DMF/1,4-dioxane/H2O afforded the solvated framework compounds [Cu-2(L-110)(H2O)(2)](DMF)(7.5)(H2O)(5) (NOTT-110) and [Cu-2(L-111)(H2O)(2)](DMF)(7.5)(H2O)(5) (NOTT-111) respectively. Crystal structure determinations confirmed that NOTT-110 and N017-111 have the same NbO framework structure, differing only at the 9 and 10 positions of the phenanthrene group. The BET surface areas for desolvated NOTT-110 and NOTT-111 were estimated to be 2960 and 2930 m(2) g(-1), respectively. Compared with their phenyl analogues, introduction of phenanthrene groups to these porous CO-carboxylate framework materials leads to an enhancement of H-2 adsorption. Thus, the H-2 isotherms for desolvated NOTT-110 and NOTT-111 confirm 2.64 and 2.56 wt% total H-2 uptake, respectively, at 1 bar and 78 K. NOTT-110 shows a high total H2 storage capacity of 7.62 wt% at 55 bar and 77 K (8.5 wt% at saturation) with a total volumetric capacity of 46.8 g L-1 at 55bar and 77 K.