Improvement of Methane–Framework Interaction by Controlling Pore Size and Functionality of Pillared MOFs

Abstract

The rational design of functionalized porous metal-organic frameworks (MOFs) for gas adsorption applications has been applied using three spacer ligands HDPT (3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine), DPT (3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine), and BPDH (2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) to synthesize TMU-34, [Zn(OBA)(HDPT)]·DMF, TMU-34(-2H), [Zn(OBA)(DPT)]·DMF, and TMU-5, [Zn(OBA)(BPDH)]·1.5DMF, respectively. By controlling the pore size and chemical functionality of these three MOFs, we can improve the interactions between CO and especially CH with the frameworks. Calculated Q(CH) for TMU-5, TMU-34, and TMU-34(-2H) are 27, 23, and 22 kJ mol, respectively. These Q values are among the highest for CH-framework interactions. For systematic comparison, two reported frameworks, TMU-4 and TMU-5, have been compared with TMU-34 and TMU-34(-2H) in CO adsorption.

Stimuli‐Responsive Metal–Organic Framework (MOF) with Chemo‐Switchable Properties for Colorimetric Detection of CHCl3

“…The MOF, [Zn(OBA)(H 2 DPT) 0.5 ] ⋅ DMF (TMU‐34), was easily synthesized on a large scale at low cost by a sonochemical reaction, as described in detail in the Experimental Section, starting from zinc acetate, H 2 OBA, and H 2 DPT (Scheme ). A powder XRD pattern of the obtained TMU‐34 showed that the sonochemical synthesis gave a material that was structurally identical to that prepared by a solvothermal method (Figure S1) …”

“…TMU‐34 is based on a binuclear Zn 2 unit, which is tetrahedrally coordinated by six carboxylate O atoms from OBA ligands to construct 2D sheets. The 2D sheets are connected through the linear H 2 DPT, extending the structure in three dimensions (Scheme ) . TMU‐34 is doubly‐interpenetrated and shows one‐dimensional 5.4×6.2 Å pores including the van der Waals radii.…”

“…TMU‐34 is doubly‐interpenetrated and shows one‐dimensional 5.4×6.2 Å pores including the van der Waals radii. The internal surface of these pores is functionalized with the dihydrotetrazine groups of the H 2 DPT ligands . To study the porosity of TMU‐34, N 2 adsorption–desorption measurements were carried out at 77 K and 1 bar on the sonochemically synthesized sample.…”

Ultrasonic‐Assisted Linker Exchange (USALE): A Novel Post‐Synthesis Method for Controlling the Functionality, Porosity, and Morphology of MOFs

“…Synthesis of pillar spacers : 3,6‐Di(4‐pyridyl)‐1,4‐dihydro‐1,2,4,5‐tetrazine (H 2 DPT) and 1,4‐bis(4‐pyridyl)‐2,3‐diaza‐1,3‐butadiene (BPDB), used as spacers, were synthesized according to the procedures reported previously …”

“…General procedure for the Henry condensation reaction : To examine the roles of porosity and functionality of the synthesized frameworks, TMU‐4, TMU‐34, SALE‐TMU‐34, and USALE‐TMU‐34, were employed in Henry condensation reactions. All the samples were activated before the catalytic tests according to the reported procedure …”