Metal Doping Induced Formation and Dynamic Gas Sorption of a Highly Porous Mesoporous MetalOrganic Framework

Abstract

A new high-porosity MOF of [Ni2.3Zn0.7(tzba)3 (H2 O)6 ]·12DMF (NiZn-MOF) processes 2D (3,6)-grid layers constructed from rare [M2 (tz)3 (H2 O)3 ] and [M(COO)3 ] nodes. The metal doping of Ni2+ and Zn2+ are crucial for the formation of the two kinds of metal nodes and subsequent synergistical assembly into the mesoporous MOF, in contrast to the formation of MIL-88-topology resembled compound of {(Me2 NH2 )[Ni3 (μ3 -OH)(tzba)3 (H2 O)3 ]·8DMF (Ni3-MOF) using single Ni2+ as metal source. The regular 2D layers stacked in parallel and ABAB fashion through interlayer hydrogen bonding, leading to a neutral framework with void fraction up to 72.1% and 1D mesoporous hexagonal channels sized at 24.0 Å in diameter. The large gas accessible porosity was revealed by the saturated N2 and CO2 uptake of 720 and 708 cm3 g-1, at 77 K and 195 K, respectively, giving a high Langmuir surface area of 2066 m2 g-1. The varying gas sorption amounts dependent on accommodated solvents and activation temperature, as well as the gate-opening behaviors in sorption isotherms, well confirm the dynamic structure response to guest species of the flexible framework.