Interactions of Alkali and Alkaline-Earth Metals in Water-Soluble Heterometallic Fe^III/M (M = Na⁺, K⁺, Ca²⁺)-Type Coordination Complex

Abstract

A water-soluble hexadentate ligand H4bedik was reproduced and employed to synthesize the corresponding mononegative [FeIIIbedik]− complex core. In the complex formation process, NaOH, KOH, and Ca­(OH)2 bases were used in order to have the corresponding cations as the counterpart of the mononegative complex core. Thus, formed complexes were designated as complex 1·H2O, Na+ ion as the countercation; complex 2, K+ ion as the countercation; and complex 3·H2O, 1/2 Ca2+ ion as the countercation. Complexes were characterized by IR and mass spectrometric techniques. Additionally, the complexes were structurally characterized by single crystal X-ray diffraction analysis. In complex 1·H2O, where the Na+ ion was present as a countercation, a two-dimensional (2D) zigzag layer structure was formed along the bc plane. The two adjacent layers were parallel to each other and propagated along the same direction, and the adjacent layers were connected to each other by H-bonding. Thus, a three-dimensional (3D) network was found. A K+ ion-containing complex 2 formed a one-dimensional (1D) linear network that propagated along the b axis. H-bonding driven 3D layers were also found in complex 2. Akin to complex 1·H2O, complex 3·H2O also formed a 2D layers structure; however, the structure was planar and not zigzag as observed in complex 1·H2O. In complex 3·H2O, two adjacent parallel layers were propagated along two opposite directions. Thermogravimetric analyses indicated that the stability of the complexes and the [FeIIIbedik]− complex core depended on the nature of the countercation. Longitudinal (r 1) and transverse relaxivity (r 2) measurements of aqueous solutions of the complexes have been performed. The value was cation-dependent and thus emphasized different interactions between [FeIIIbedik]− units in the presence of different cations.

Water-soluble chiral coordination polymers of Li+, Na+, K+, and Ba2+ with an anionic iron(iii) complex of a l-threonine derivative and a significant red shift of visible spectra with Al3+ salt

“…They show strong and sharp asymmetric carboxylate stretches 1600–1628 cm −1 , the same region where reported complexes with similar ligands (1580–1630 cm −1 ) were observed. 30–33,39,40…”

“…Earlier, our interest was in forming larger chiral assemblies from rigid metal complexes of relatively flexible amino acidderived ligands. [30][31][32][33]39,40 Other forms of assemblies, such as coordination networks, were mostly ignored because of their poor solubility in most common solvents, which limited experiments with guest molecules. 31 However, we did find that bis-complexes of Cu(II) and Ni(II) with amino acid derived ligands themselves can act as ligands to alkali metal ions, but the structural motif of the complex was not suitable for network formation.…”

“…They show strong and sharp asymmetric carboxylate stretches 1600-1628 cm −1 , the same region where reported complexes with similar ligands (1580-1630 cm −1 ) were observed. [30][31][32][33]39,40 All four complexes are soluble in water and methanol and could be recrystallized in crystalline from either of the solvents. The crystals were dried inside a vacuum desiccator for several days before analysis and bulk measurements.…”

Synthesis, Structures, and Properties of Five Metal‐Organic Frameworks Based on Oxidized 3,3′‐Azodibenzoic Acid and Different N‐Donor Ligands

“…It is well known that the structure of MOFs is usually influenced by many factors, for example metal ions, organic ligands, the ratio of metal/ligand, reaction temperatures, pH, and solvents. [7][8][9][10] Among them, the organic ligands paly an extremely important role because they are highly tunable, and even small changes can result in significant variousness for both architectures and properties. [9] This work is mainly devoted to exploring the effects of ligands with different length and configuration for regulating the structural assembly, which may provide further insight into the design of new functional crystalline materials.…”

“…However, the rational design and synthesis of MOFs with desired structures and properties is still a long‐term challenge. It is well known that the structure of MOFs is usually influenced by many factors, for example metal ions, organic ligands, the ratio of metal/ligand, reaction temperatures, pH, and solvents . Among them, the organic ligands paly an extremely important role because they are highly tunable, and even small changes can result in significant variousness for both architectures and properties .…”