Synthesis, crystal structure and magneto-structural studies of 2D copper(II) coordination polymer containing l -alanine amino acid

Spherulite-like Ni(II)(l-glutaminato·H2O)2 Complex: Morphological Microstructure, DFT-Assisted Crystal Structure Determination, and Vibrational Analysis

l-glutamine complexes with transition metals have already been reported in the literature, but there have been no studies on l-glutamine complexes with Ni2+. Here, the new polycrystalline spherulite-like Ni(II)(l-glutaminato·H2O)2 complex was synthesized, and powder X-ray diffraction (PXRD) measurements and density functional theory (DFT) calculations were performed to determine its crystal structure. SEM images revealed the beautiful morphological microstructure of the new spherulite-like complex's surface and internal region. Thermogravimetric analysis (TGA) and vibrational spectroscopic techniques (infrared and Raman) were also performed. A mass loss observed at around 160 °C, equivalent to the mass of two water molecules, was determined by TGA. DFT calculations were initially performed to generate the most stable molecule and assist in crystal structure determination using the PXRD data. Five conformations of the complex were established, and these structures were optimized with the B3LYP hybrid functional and Def2-tzvp basis function for the nickel atom and 6-311++G(d,p) for the other atoms. Scanning calculations were performed to construct the potential energy surfaces and identify the most stable structure. From a PXRD measurement and the possible configurations of the optimized molecules, the Ni(II)(l-glutaminato·H2O)2 crystal structure was solved using a simulated annealing approach. The new compound crystallized in a triclinic system with a P1̅ space group.

Copper(II) coordination polymer based on l-arginine as a supramolecular hybrid inorganic–organic material: synthesis, structural, spectroscopic and magnetic properties

We report the synthesis and structural, spectroscopic and magnetic properties of new 1D coordination polymeric complex {[Cu(μ-l-Arg)2]SO4⋅1.5H2O}n (1) that contains asymmetric μ−O,O’ carboxylic bridge linking distorted square-pyramidal [Cu(μ-l-Arg)2]2+ coordination units. In 1D, the syn−anti−μ2−η1:η1zigzag polymer conformation, the adjacent Cu(II) ions are distanced by 5.707 Å, and the subsequent Cu∙∙∙Cu proximity in 1D-coordination chain equals 6.978 Å. Detailed interpretation of IR and Raman spectra of l-arginine and 1 was performed. The principal components of the g tensor determined from EPR experiments (gx = 2.059, gy = 2.075, gz = 2.228) indicate nearly axial symmetry of Cu(II) coordination sphere and correspond to the unpaired electron occupying the dx2–y2 orbital. The single broad band at 16,200 cm–1, characteristic of d−d transition, is assigned to the dominant dublet-dublet 2B1g(dx2–y2)→ 2Eg(dyz≈dxz) transition. Magnetic susceptibility measurements have revealed ferromagnetic coupling between the Cu(II) ions within the 1D-coordination chain, while the intermolecular coupling is antiferromagnetic.

Graphical Abstract

A new mixed-valence CuI/CuII three-dimensional coordination polymer constructed with an N,O-donor ligand generated via solvothermal synthesis: structural features and magnetic properties

A new mixed-valence CuI/CuII three-dimensional coordination polymer, poly[[diaquabis[μ4-2-(pyrazin-2-yl)quinoline-4-carboxylato]dicopper(I)copper(II)] bis(tetrafluoridoborate)], {[Cu3(C14H8N3O2)2(H2O)2](BF4)2} n , was synthesized and characterized, with 2-(pyrazin-2-yl)quinoline-4-carboxylic acid being employed as a linker ligand. The ligand was isolated as its hydrochloride salt, 4-carboxy-2-(pyrazin-2-yl)quinolin-1-ium chloride dihydrate, C14H10N3O2 +·Cl−·2H2O. The compounds show luminescence at 550 nm for the ligand and at 565 nm for the polymer at 297 K. The ligand structure was rationalized by means of quantum-chemical calculations, which led to a similar conformation to that determined from X-ray diffraction studies.

A tryptophan-based copper(ii) coordination polymer: catalytic activity towards Suzuki–Miyaura cross-coupling reactions

An unusual tryptophan coordination mode with copper(ii) wherein l-tryp is coordinated through the carboxylate and amine groups. A heterogeneous catalyst for the Suzuki cross-coupling reaction with ∼98% yield under normal reaction conditions.

Ferromagnetically Coupled Copper(II) Clusters Incorporated in Functionalized Boltorn H30 Hyperbranched Polymer Architecture: ESR, Magnetic Susceptibility Measurements, and Quantum-Chemical Calculations

The unusual temperature behavior of the electron spin resonance (ESR) spectra and magnetic properties are experimentally observed in copper(II) complexes with a dendritic ligand based on the Boltorn H30 polymer (Perstorp Specialty Chemicals AB, Sweden) functionalized with fumaric acid residues in a molar ratio of 1:6. The ESR spectra at low temperatures show signs of transition to higher spin states at temperatures below 8-10 K, and the temperature dependences of the integral ESR signal intensities and magnetic susceptibility show the positive deviation from the Curie-Weiss law, thereby pointing to the presence of ferromagnetic exchange interactions in the system under study. The values of the exchange interaction parameters are calculated by quantum-chemical simulation of the possible structure of the copper(II) complex when assuming the formation of trinuclear coordination sites embedded in the hyperbranched polymer structure. The results of density functional theory calculations indicate the possibility of ferromagnetic exchange through carboxylate bridges in the trinuclear magnetic clusters, and the calculated values of the exchange interaction parameters make it possible to construct theoretical curves of the temperature dependence of the effective magnetic moment, which satisfactorily fit the experimental data, especially considering that polymers are characterized by disperse molecular weights and chemical structures.