Pillared, 3D Metal-Organic Frameworks with Rectangular Channels. Synthesis and Characterization of Coordination Polymers Based on Tricadmium Carboxylates

Hydro(solvo)thermal reactions between cadmium(II) perchlorate and 4-pyridinecarboxaldehyde in the presence
of various guest molecules have resulted in a series of 3-D coordination polymers based on tricadmium carboxylates
[Cd6(isonicotinate)10(H2O)2](ClO4)2(EtOH)4(H2O)4, 1, [Cd3(isonicotinate)5(EtOH)](ClO4)(EtOH)(4-nitroaniline)0.5,
2, and [Cd6(isonicotinate)11](ClO4)(EtOH)2(H2O)2(4-cyanopyridine)0.5, 3. X-ray single crystal structure determinations show that they exhibit similar pillared, 3D framework structures based on tricadmium carboxylate building
blocks. Rectangular channels are clearly present in these polymeric networks and are occupied by perchlorate
anions and disordered guest molecules. Quantitative NMR and X-ray powder diffraction studies and thermogravimetric analyses (TGA) reveal that these coordination networks are capable of accommodating different guest
molecules. More significantly, the guest molecules can be readily removed via evacuation to result in nanoporous
polymeric coordination networks retaining the framework structures of the pristine solids. Crystal data for 1: 
monoclinic space group P21/n, a = 19.041(1) Å, b = 23.654(1) Å, c = 21.568(1) Å, β = 95.440(1)°, and Z =
4. Crystal data for 2:  triclinic space group P1̄, a = 12.050(1) Å, b = 12.277(1) Å, c = 19.103(1) Å, α =
91.669(1)°, β = 96.850(1)°, γ = 117.945(1)°, and Z = 2. Crystal data for 3:  monoclinic space group P21/n, a
= 19.038(1) Å, b = 23.834(1) Å, c = 21.756(1) Å, β = 97.580(1)°, and Z = 4.