1D and 2D Thiazole-Based Copper(II) Coordination Polymers: Synthesis and Applications in Carbon Dioxide Capture

The reaction of different copper(II) salts with a class of thiazole-based ligands under solvothermal conditions produces three crystalline 1D/2D coordination polymers: [Cu(κ-N-thiazole)4(SiF6)]∞ (1 (1D)), {Cu[μ-(κ-N:κ-COO)-L1]2⋅(H2O)}∞ (2 (2D); HL1=2-aminothiazole-5-carboxylic acid), and {Cu[μ-(κ-N:κ-COO)-L2]2⋅1.5 (H2O)}∞ (3 (2D); HL2=thiazole-5-carboxylic acid). All the materials have been characterized through common solid-state techniques: single-crystal (XRD) and (variable-temperature) powder X-ray diffraction (PXRD), infrared spectroscopy (IR), thermogravimetric analysis combined with mass spectrometry (TGA-MS), and BET surface area and pore-size distribution measurements. Polymer 3 shows a porous structure made of squared channels formed by the ordered stacking of the planar sheets along the a crystallographic axis (inner surface area equal to 15 m2 g−1, as inferred from N2 adsorption at T=77 K on the pre-activated form), and it has been exploited for CO2 physisorption at ambient temperature (T=303 K) and pressure (pinline image max.=920 torr). A remarkable CO2 uptake equal to 9.0 wt % was recorded under these mild conditions, thereby making the material promising for carbon dioxide capture in post-combustion flue gas, in which the key factor for a successful performance is the high chemical selectivity for CO2 over N2.