The roles of H-bonding, π-stacking, and antiparallel CO ⋯ CO interactions in the formation of a new Gd(III) coordination polymer based on pyridine-2,6-dicarboxylic acid

Crystal structures of two SmIII complexes with dipicolinate [DPA]2- ligands: comparison of luminescent properties of products obtained at different pH values

The formation of the two title compounds, Na3[Sm(DPA)3]·14H2O tris-odium tris-(pyridine-2,6-di-carboxyl-ato-κ3 O 2,N,O 6)samarate(III) tetra-deca-hydrate, Na3[Sm(C7H3NO4)3]·14H2O, and catena-poly[[[di-aqua-(6-carb-oxy-pyridine-2-carb-oxyl-ato-κ3 O 2,N,O 6)samarium(III)]-μ-pyridine-2,6-di-carboxyl-ato-κ4 O 2,N,O 6:O 2] tetra-hydrate], {[Sm(C7H3NO4)(C7H4NO4)(H2O)2]·4H2O}n, depends on the pH value adjusted with NaOH solution. In both crystal structures, the coordination spheres of the SmIII cations were found to be best described by a tricapped trigonal prism (TTP), with a more regular O6N3 donor set for Na3[Sm(DPA)3]·14H2O than that of O7N2 for [Sm(DPA)(HDPA)(H2O)2]·4H2O. The supra-molecular features of both crystal structures are dominated by O-H⋯O hydrogen bonds between water mol-ecules and the O atoms of the dipicolinato ligands. Samples were made from solutions at pH = 2, pH = 5, pH = 7, and pH = 10, and the crystals present in each sample were ground to a powder. The powder samples were analyzed with powder X-ray diffraction and luminescence spectroscopy. The splitting of the bands in the luminescence spectra recorded on powders at 77 K was observed to vary with the pH.

Developing a magnetic metal organic framework of copper bearing a mixed azido/butane-1,4-dicarboxylate bridge: magnetic and gas adsorption properties

A magnetic metal organic framework {[Cu(but-1,4-dc)0.5(N3)(H2O)]·H2O}n (MFUM-1(Cu)) (but-1,4-dc = butane-1,4-dicarboxylate) was synthesized and characterized structurally and magnetically. In MFUM-1(Cu), each CuII ion has a distorted octahedral geometry with an obvious Jahn-Teller distortion, where the coordination environment is composed of mixed EO-azido/aliphatic based carboxylate/H2O threefold bridges. These bridges extend the structure of MFUM-1(Cu) in two dimensions by covalent connectivity and form square-shaped channels. Also, a study was done to determine the effectiveness of sonochemical synthesis for the preparation of nano-sheets of MFUM-1(Cu) and subsequently the influence of particle size on physical properties such as magnetic behavior and thermal stability. The particles were characterized by elemental analyses, infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD) analyses. The effects of parameters such as concentration, solvent, and reaction time on the size distribution, morphology, and yield of product were carefully studied. The magnetic properties of MFUM-1(Cu) and corresponding nano-structure were examined which indicated metamagnetism with strong intrachain ferromagnetic coupling versus the weak interchain antiferromagnetic coupling. Finally, the application of MFUM-1(Cu) in the separation of carbon dioxide from nitrogen and also from methane was theoretically investigated. High calculated selectivity of CO2 over N2 and CH4 reveals the potential application of MFUM-1(Cu) in practical systems of gas separation.