Synthesis and hydrogen gas storage properties of metal complexes including dicarboxylic acid derivatives

• In this study, five new porous metal complexes were synthesized.
• The porous complexes were characterized by spectroscopic methods.
• The gas adsorption capacities of the synthesized complexes have been examined.
• The adsorption isotherm, surface area, porous size of complexes were analyzed.

New porous metal–organic coordination polymers (CPs) were synthesized by condensation of 4,5-imidazole dicarboxylic acid ligand (L) with Mo(III), W(VI), Ce(III), Sm(III), and Sn(IV) metal ions. Synthesized complexes were successfully characterized by elemental analysis, FT-IR, 1H NMR, LC–MS, ICP-MS. Gas storage and adsorption properties of these complexes were investigated via BET measurements after calculating micro–meso pore volume of the complexes. Sorption property of N2 was performed at temperature of 77 K and pressure of 0.6 bar. Observations depicted that the size of pore was “meso” and the specific surface area determined from nitrogen adsorption was 90 m2 g−1. On the other hand, BET measurements indicated that all of these complexes were capable of occluding optimal amount of gas. In general, hydrogen-storage behavior of the synthesized complexes showed a higher surface area and larger pore volumes in which L1Sm had more storage capacity due to its larger surface area and pore size than others. The amounts of hydrogen adsorbed at 298 K and 200 bar reached approximately value of 2.85 wt.%.

New porous coordination polymers were synthesized with 4,5-imidazole-dicarboxylic acid ligand (L) and Mo(III), W(VI), Ce(III), Sm(III), Sn(IV). Nitrogen gas adsorption–desorption of complexes were carried out on surface area measurement device. Then, hydrogen gas storage capacities of complexes were carried out on high-pressure volumetric device at 298 K and 200 bar in the figure. Gas volume–relative pressure isotherms and specific surface areas of complexes were evaluated by BET technique.Figure optionsDownload as PowerPoint slide