Study of structure and two-dimension correlation infrared spectroscopy on three rare-earth/3-methylbenzoic acid complexes

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS), part I. Yesterday and today

This comprehensive survey review, as the first of three parts, compiles past developments and early concepts of two-dimensional correlation spectroscopy (2D-COS) and subsequent evolution, as well as its early applications in various fields for the last 35 years. It covers past review articles, books, proceedings, and numerous research papers published on 2D-COS. 2D-COS continues to evolve and grow with new significant developments and versatile applications in diverse scientific fields. The healthy, vigorous, and diverse progress of 2D-COS studies in many fields confirms that it is well accepted as a powerful analytical technique to provide the in-depth understanding of systems of interest.

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

Two new coordination polymers [Pr(PCPA)₃(H₂O)]_n1 and [Pr₂(PCPA)₆(H₂O)₃]_n·nH₂O 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.

Post-Synthetic Shaping of Porosity and Crystal Structure of Ln-Bipy-MOFs by Thermal Treatment

The reaction of anhydrous lanthanide chlorides together with 4,4′-bipyridine yields the MOFs ∞2[Ln₂Cl₆(bipy)₃]·2bipy, with Ln = Pr − Yb, bipy = 4,4′-bipyridine, and ∞3[La₂Cl₆(bipy)₅]·4bipy. Post-synthetic thermal treatment in combination with different vacuum conditions was successfully used to shape the porosity of the MOFs. In addition to the MOFs microporosity, a tuneable mesoporosity can be implemented depending on the treatment conditions as a surface morphological modification. Furthermore, thermal treatment without vacuum results in several identifiable crystalline high-temperature phases. Instead of collapse of the frameworks upon heating, further aggregation under release of bipy is observed. ∞3[LaCl₃(bipy)] and ∞2[Ln₃Cl₉(bipy)₃], with Ln = La, Pr, Sm, and ∞1[Ho₂Cl₆(bipy)₂] were identified and characterized, which can also exhibit luminescence. Besides being released upon heating, the linker 4,4′-bipyridine can undergo activation of C-C bonding in ortho-position leading to the in-situ formation of 4,4′:2′,2′′:4′′,4′′′-quaterpyridine (qtpy). qtpy can thereby function as linker itself, as shown for the formation of the network ∞2[Gd₂Cl₆(qtpy)₂(bipy)₂]·bipy. Altogether, the manuscript elaborates the influence of thermal treatment beyond the usual activation procedures reported for MOFs.

catena-Poly[[bis-(3-methyl-benzoato-κO,O')lead(II)]-μ-4,4'-bipyridine-κN:N']

In the title complex, [Pb(C₈H₇O₂)₂(C₁₀H₈N₂)]_n, the Pb^II atom is located on a twofold rotation axis and is six-coordinated by four carboxyl­ate O atoms from two 3-methyl­benzoate ligands and two N atoms from two 4,4′-bipyridine (4,4′-bpy) ligands, displaying a hemi-directed coordination. The 4,4′-bpy ligand has an inversion center at the mid-point of the central C—C bond. The Pb^II atoms are linked by bidentate bridging 4,4′-bpy into a chain along [101]. These chains are further connected into layers via C—H⋯O hydrogen bonds.