Synthesis, crystal structure, and two-dimension correlation infrared spectroscopy on two novel Pr carboxylic acid coordination polymers.

Two new coordination polymers [Pr(PCPA)(HO)]1 and [Pr(PCPA)(HO)]·nHO 2(PCPA = p-chlorophenoxyacetic acid) have been synthesized under similar conditions by the hydrothermal method and characterized by single-crystal X-ray diffraction, elemental analyses, powder X-ray diffraction (PXRD) analysis, IR spectroscopy, two-dimensional correlation infrared spectroscopy(2D-IR COS) and ultraviolet-visible diffuse reflection integral spectroscopy (UV-Vis DRIS). 1 displays a 1D infinite chain, which is further linked by O/CH⋯O hydrogen bonds to form a 3D supra-molecular architecture. 2 shows a 2D layer structure, which is extended by CH⋯Cl hydrogen bonds generating a 3D network. Noteworthy, we also studied 2D-IR COS under the thermal perturbation to contribute to the development of theory. The 2D-IR correlation spectroscopy analysis is consistent with the analysis of structure and it is superior to 1D IR spectroscopy especially in the coordinated carboxyl group.