A series of entangled MOFs constructed from flexible dipyridyl piperazine and rigid dicarboxylate: interpenetration, self-penetration, and polycatenation

By employing a flexible dipyridyl piperazine and a rigid linear dicarboxylate, four MOFs with different entangled structures involving a 3D inclined polycatenane and a 3D self-penetrated framework incorporating cyclic [3]catenane were isolated.

Poly[(μ(2)-4,4'-bipyridine-κN:N')bis-(μ(2)-2-phen-oxy-propionato-κO:O')cobalt(II)]

In the polymeric title compound, [Co(C₉H₉O₃)₂(C₁₀H₈N₂)]_n, the Co^II ion is located on a twofold rotation axis and is six-coordinated by two N atoms from two 4,4′-bipyridine (4,4′-bipy) ligands in axial positions and by four O atoms from four 2-phen­oxy­propionate (POPA) anions in equatorial positions, defining a slightly distorted octa­hedral geometry. The carboxyl­ate group of the POPA anion displays a bis-monodentate mode, linking pairs of Co^II ions into a chain parallel to [001]. Adjacent chains are connected in a perpendicular manner through 4,4′-bipy ligands into layers parallel to (100). The 4,4′-bipy ligand is likewise located on a twofold rotation axis, with a dihedral angle between the two pyridine rings of 57.05 (7)°. C—H⋯O hydrogen-bonding inter­actions are present within the layers. π–π stacking inter­actions between the POPA benzene rings of neighbouring layers [centroid-to-centroid distance = 3.976 (3) Å and plane-to-plane distance = 3.618 (3) Å] stabilize the packing of the structure.

A series of lanthanide-organic polymers incorporating nitrogen-heterocyclic and aliphatic carboxylate mixed-ligands: structures, luminescent and magnetic properties

Seven new lanthanide-organic coordination polymers incorporating both nitrogen heterocyclic dicarboxylate and various auxiliary ligands, {[Ln(3)(Hpimda)(4)(mu(2)-HCOO).5H(2)O].H(2)O}(n)} Ln = Sm (1), Ln = Eu (2), Ln = Gd (3), Ln = Dy (4), Ln = Ho (5), {[Ce(2)(Hpimda)(2)(mu(4)-C(2)O(4)).8H(2)O].2H(2)O}(n) (6), {[Yb(2)(pyda)(mu(4)-C(2)O(4))(2).4H(2)O].3H(2)O}(n) (7) (H(3)pimda = 1H-2-propyl-4,5-imidazoledicarboxylic acid, H(2)pyda = 2,6-pyridinedicarboxylic acid) have been fabricated successfully and characterized systematically. Complexes 1-5 are isomorphous and isostructural, and are built from two-dimensional (2-D) double-decker networks based on the tetranuclear basic carboxylate as a secondary building unit (SBU). Both polymers 6 and 7 feature a (3,4)-connected 3-D framework consisting of 2-D lanthanide-organic hexagonal grids, which are further interlinked via the mu(4)-oxalate ligand. The results of magnetic determination show the same end-to-end bridging fashion of formate group results in different magnetic properties occurring between lanthanide centers. The luminescence emission spectra of the complexes vary depending on the lanthanide ion present.