A Metal–Ligand Layer Compatible with Various Types of Pillars for New Porous Coordination Polymers
journal contribution
posted on 2020-09-15, 21:03 authored by Yun Li, Zong-Wen Mo, Xue-Wen Zhang, Kai Zheng, Dong-Dong Zhou, Jie-Peng ZhangPillared-layer
structures are classic for porous coordination polymers
(PCPs), but suitable metal–ligand
layers for such structures are rare. Here, we report a cationic {Zn2(pzdc)}+ (H3pzdc = 3,5-pyrazoledicarboxylic
acid) layer compatible with various types of pillar ligands. Solvothermal
reactions of Zn(NO3)2·6H2O and
H3pzdc with 4-(pyridin-4-yl)-1H-pyrazole
(Hpypz), 1,4-benzenedicarboxylic acid (H2bdc), or 2-amino-1,4-benzenedicarboxylic
acid (H2abdc) in a mixed solvent of H2O and N,N-dimethylformamide (DMF) produced three pillared-layer
PCPs, namely [Zn4(pzdc)2(pypz)2]·guest
(1), [Zn4(pzdc)2(bdc)(H2O)1.53(DMF)0.47]·guest (2), and [Zn4(pzdc)2(abdc)(H2O)1.52(DMF)0.48]·guest (3), respectively.
Single-crystal X-ray analyses revealed that the {Zn2(pzdc)}+ layers are fully pillared by pypz− in 1 and half pillared by bdc2− and abdc2− in 2 and 3, because the
anionic pillars possess different charges. Consequently, 1 shows one-dimensional (1D) channels with a small porosity and 2 and 3 show 2D channels with large porosities,
both of which were verified by N2 and CO2 adsorption
isotherms. While 1 has no coordinated solvent molecules
and exhibits a high water stability, 2 and 3 possess coordinated solvent molecules and quickly transform to crystals
of 2D coordination networks in water, [Zn4(pzdc)2(OH)2(H2O)6]·H2bdc·4H2O (4) and [Zn4(pzdc)2(H2abdc)(OH)2(H2O)5]·2H2O (5), respectively, which can be further exfoliated
into ultrathin nanosheets in an ammonia solution.
