Synthesis, Structures, and Properties of Two Three-Dimensional Metal–Organic Frameworks, Based on Concurrent Ligand Extension

A tritopic carboxylate ligand, tris­(4′-carboxybiphenyl)­amine
(L-H3), has been synthesized
and applied in the construction of microporous metal–organic
frameworks (MOFs). Two novel metal–organic frameworks (MOFs),
{[Zn2(L)­(OH)]·2DMF·H2O}∞ (1) and {[Cu­(L-H)­(DMA)]·DMA·2H2O}∞ (2), have been constructed
out of L-H3, Zn2+,
and Cu2+, respectively. 1 has a 2-fold interpenetrating
three-dimensional framework formed by L connectors and
the [Zn2(CO2)3] secondary building
units (SBUs). As for 1, it is worth pointing out that
one μ2–OH group links two Zn atoms between
two neighboring SBUs to produce interesting Zn–O–Zn
zigzag chains in the structure. 2 has a two-dimensional
grid sheet formed by L-H connectors and the typical paddle-wheel
[Cu2(CO2)4] SBUs. Two-dimensional
(2D) sheets nest with each other, which finally forms a three-dimensional
(3D) nested framework. Two MOFs are characterized by infrared (IR)
spectroscopy, thermogravimetry, single-crystal and elemental analyses,
and powder X-ray diffraction methods. Framework 1′
exhibits high permanent porosity (Langmuir surface area = 848 m2/g), high thermal stability (up to 450 °C), highly active
properties for Friedel–Crafts alkylation reaction, as well
as the potential application for the CO2 gas storage and
luminescent material. The catalytic results reveal that 2′ is indeed an efficient heterogeneous catalyst for olefin
epoxidation reactions.