Heterometallic Copper(II)–Potassium 3D Coordination Polymers Driven by Multifunctionalized Azo Derivatives of β-Diketones

New 3D Cu(II)-K coordination polymers (CPs), [CuK(μ7-L1)(H2O)]n·nH2O (1), and [CuK(μ5-L2)(H2O)]n·2nH2O (2), were easily generated by self-assembly from copper(II) nitrate, potassium hydroxide, and azo derivatives of β-diketones, namely 3-(2-hydroxy-3-sulfo-5-chlorophenylhydrazo)pentane-2,4-dione (H3L1) or 3-(2-hydroxy-3-sulfo-5-nitrophenylhydrazo)pentane-2,4-dione (H3L2). The single-crystal structures of 1 and 2 disclose similar 3D metal–organic networks, driven by the 5-connected potassium, 6-connected L1, or 5-connected L2 nodes. The topological analysis of 1 reveals a rare binodal 5,6-connected underlying net with an unprecedented topology defined by the point (Schläfli) symbol of (3·45·53·6)(32·46·53·64), while 2 features a uninodal 5-connected net with the bnn (hexagonal boron nitride) topology and the point symbol of (46·64). Both networks possess voids filled by crystallization water molecules, the reversible escape and binding of which was studied by thermal analyses. Upon a dehydration–adsorption cycle, 1 undergoes structural changes, although without loss of crystallinity, while 2 basically preserves its initial structure, as confirmed by X-ray powder diffraction analyses. Besides, 1 and 2 act as catalyst precursors for the aerobic TEMPO-mediated selective oxidation of benzyl alcohol to benzaldehyde in aqueous medium.