Synthesis and Characterization of Polyhedral-Based Metal–Organic Frameworks Using a Flexible Bipyrazole Ligand: Topological Analysis and Sorption Property Studies

Six
porous metal–organic frameworks (MOFs), {[Ni­(BTC)0.66­(BPz)2]­·2MeOH­·4H2O}n (1), {[Co­(BTC)0.66­(BPz)2]­·2MeOH­·4H2O}n (2), {[Mn­(BTC)0.66­(BPz)2]­·2MeOH­·4H2O}n (3), {[Cd­(BDC)­(BPz)­(H2O)]­·2MeOH­·DMF}n (4), {[Cd2(NH2-BDC)2­(BPz)­(H2O)]­·MeOH­·H2O­·DMF}n (5), and {[Co­(BDC)­(BPz)­(H2O)]}n (6) (where H3BTC = 1,3,5-benzenetricarboxylic
acid, H2BDC = 1,4-benzenedicarboxylic acid, NH2-H2BDC = 2-amino-1,4-benzenedicarboxylic acid, and BPz
= 3,3′,5,5′-tetramethyl-4,4′-bipyrazole), were
obtained through a solvent diffusion technique and characterized.
The networks exhibit a variety of topologies: 1, 2, and 3 are isostructural and possess octahedral
and cuboctahedra type cages and exhibit 3,6-c binodal net having loh1 topology, 4 is
a two-dimensional MOF having one-dimensional open channels with a
4-c uninodal net having sql topology, 5 exhibits a three-dimensional (3D) porous MOF having a 3,3,4,8-c
net with a new topology having the name, skr1, whereas 6 discloses a 3D nonporous network
which exhibits a 4-c uninodal net having CdSO4 topology.
Being isostructural, gas sorption studies of 1–3 show nearly the same CO2 sorption at 195 K of
∼90 mL g–1, whereas 4 and 5 show a maximum uptake of 42 and 37 mL g–1 at 195 K. Vapor sorption studies of 1–3 reveal stepwise uptake of water with a final amount reached
to nearly 350 mL g–1, whereas 4 and 5 show maximum uptake of 110 and 90 mL g–1, respectively. Compared to the free ligand BPz, photoluminescence
studies of 4 and 5 show red shifts and emit
in the blue-green region with λmax at 430 and 472
nm for 4 and 5, respectively.

六种多孔金属-有机框架（MOF），包括 {[Ni(BTC)0.66(BPz)2]·2MeOH·4H2O}n (1)、{[Co(BTC)0.66(BPz)2]·2MeOH·4H2O}n (2)、{[Mn(BTC)0.66(BPz)2]·2MeOH·4H2O}n (3)、{[Cd(BDC)(BPz)(H2O)]·2MeOH·DMF}n (4)、{[Cd2(NH2-BDC)2(BPz)(H2O)]·MeOH·H2O·DMF}n (5) 和 {[Co(BDC)(BPz)(H2O)]}n (6)（其中 H3BTC 代表 1,3,5-苯三羧酸，H2BDC 代表 1,4-苯二甲酸，NH2-H2BDC 代表 2-氨基-1,4-苯二甲酸，BPz 代表 3,3′,5,5′-四甲基-4,4′-双吡唑），通过溶剂扩散技术制备并进行了表征。这些网络结构呈现出多样化的拓扑结构：1、2 和 3 具有相同的结构，并拥有八面体和立方八面体类型的笼状结构，展现出 3,6-c 双结点网络，具有 loh1 拓扑，4 是一种二维 MOF，具有一维开放式通道，拥有 4-c 单结点网络，拓扑为 sql，5 展示了一种三维（3D）多孔 MOF，具有 3,3,4,8-c 网络和名为 skr1 的新型拓扑，而 6 则揭示了具有 CdSO4 拓扑的 3D 非多孔网络。由于结构相同，1-3 的气体吸附研究显示在 195 K 下 CO2 吸附量相近，约为 90 mL g–1，而 4 和 5 在 195 K 下分别显示出最大吸附量为 42 和 37 mL g–1。1-3 的蒸汽吸附研究揭示了逐步的水分吸附，最终吸附量接近 350 mL g–1，而 4 和 5 分别显示出最大吸附量为 110 和 90 mL g–1。与游离配体 BPz 相比，4 和 5 的光致发光研究显示出红移，分别在 430 nm 和 472 nm 处发射蓝绿色光。}