New Coordination Polymers and Porous Supramolecular
Metal Organic Network Based on the Trinuclear Triangular Secondary
Building Unit [Cu<sub>3</sub>(μ<sub>3</sub>‑OH)(μ-pz)<sub>3</sub>]<sup>2+</sup> and 4,4′-Bypiridine. 1°
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Abstract
The
trinuclear triangular Cu<sup>II</sup> complex [Cu<sub>3</sub>(μ<sub>3</sub>-OH)(μ-pz)<sub>3</sub>(HCOO)<sub>2</sub>(Hpz)<sub>2</sub>] (Hpz = pyrazole) reacts with 4,4′-bipyridine (bpy) yielding
a two-dimensional (2D) waved sheets, two three-dimensional (3D) coordination
polymers (CPs), as well as a hexanuclear Cu<sup>II</sup> cluster,
depending on the reagent ratios and reaction conditions. Single crystal
X-ray diffraction (XRD) determinations point out that, while CPs crystal
structures are not porous, the hexanuclear Cu<sup>II</sup> clusters
are packed in the solid state generating a stable porous 3D supramolecular
network, where two kinds of perpendicular, hydrophobic channels (ca.
4.83 × 5.86 Å<sup>2</sup> and 4.99 × 4.79 Å<sup>2</sup>, corresponding to the 24.7% of the total crystal volume)
are present. In the “as-synthesized” compound, channels
of one kind are empty, while the other ones are occupied by guest
bpy molecules which can be removed by soaking the crystals in suitable
solvents (benzene, toluene, <i>c</i>-hexane) maintaining
intact the crystal skeleton. Moreover, two of the above complexes
act as catalysts (or catalyst precursors) in the peroxidative oxidation
of cyclohexane