Correlation of Mesh Size of Metal–Carboxylate Layer with Degree of Interpenetration in Pillared-Layer Frameworks

Two porous cobal–organic frameworks
showing threefold interpenetration
of pillared-layer structures, constructed from two-dimensional (2D)
neutral metal–carboxylate layers and neutral bis-pyridyl-bis-amide
pillars, were hydro­(solvo)­thermally synthesized and structurally characterized
by single-crystal X-ray diffraction. Compound {[Co2(thdc)2(bpda)2(DMF)]·2DMF}n (1, thdc = 2,5-thiophenedicarboxylate; bpda = N,N′-bis­(4-pyridinyl)-1,4-benzenedicarboxamide) adopts
a uninodal 6-connected three-dimensional (3D) framework with a {412·63}-pcu topology in which 2D
rhomboid-like 44-sql Co–thdc layers
are pillared by bpda ligands. While compound {[Co3(btc)2(bpda)3]·2DMF·9H2O}n (2, btc = 1,3,5-benzenetricarboxylate)
is composed of a binodal (3,4)-connected 3D framework with a (63)2(64·8·10)3 topology
that can be described in terms of two building subunitsa 2D
porous honeycomb-like 63-hcb Co–btc
layer and a bpda pillar. An in-depth analysis showed that the mesh
size of the metal–carboxylate layer, in addition to the pillar
length, is highly correlated with the degree of interpenetration in
the pillared-layer framework. The structural characteristics of frameworks 1 and 2 fully support this relationship.