2D Coordination Polymer Built from Lithium Dimethylmalonate and Co^II Ions: The Influence of Dehydration on Spectral and Magnetic Properties

Abstract

2D coordination polymer [Li 2 Co(H 2 O) 4 (Me 2 Mal) 2 ] n (1) was synthesized by interaction of lithium dimethylmalonate (Li 2 Me 2 mal) and cobalt(II) acetate. The structure of 1 can be described as {Li(H 2 O) 2 (Me 2 Mal-κ-O,O′)} anions linked by Co II cations through bridging water molecules and Me 2 Mal 2dianions. Upon heating to 130-190°C, compound 1 loses water molecules and transforms into [Li 2 Co(Me 2 Mal) 2 ] n (2). Compound 2 is non-porous and amorphous, its rehydration by water leads to formation of 1, as shown by powder XRD. Dehydration of 1 is associated with a drastic color change from pink to violet. The temperature dependency of magnetic susceptibility M for Coordination polymers (CP) have unique potential to prepare compounds with desired optical, magnetic, sorption or catalytic properties, because the metal ions, polynuclear building blocks, and bridging ligands can be varied over a wide range. [1][2][3] Combination of several properties in one compound, especially the ability to change certain characteristic under the action associated with another property, can be utilized for creation of materials with tunable properties, which can be used as active bodies for optical, magnetic or conducting sensors, displays, indicators, etc. [4,5] For example, the reversible uptake of guest molecules can lead to a change of optical (color), [6][7][8] magnetic properties (magnetic susceptibility, temperature of spin-crossover, or magnetic ordering), [8][9][10][11] or luminescence. [12][13][14] Such changes are often associated with structural transformations, [a] N.1396 Figure 2. Topological representations of the underlying network (a) and further simplified binodal 3,6-connected net 3 2 6 1 topology kgd (b) for 1. Key: Li I : yellow, Co II : pink, Me 2 Mal 2-: blue.

Hexanuclear 3d − 4f metal–organic cages assembled from a carboxylic acid‐functionalized tris‐triazamacrocycle for highly selective fluorescent sensing of picric acid

“…The bathochromic shift of the π − π* transition with respect to the free ligand is an indication of the complexation of the ligand with metals, which seems to bring about a significant impact on the electronic properties of the aromatic core in the ligand. The 4 T 1g → 4 T 1g (P) transition of the high‐spin Co II in octahedral geometry appears as a weak broad band at 514 nm ( ε = 1.56 × 10 3 M −1 cm −1 ) and 547 nm ( ε = 1.65 × 10 3 M −1 cm −1 ) for 1 and 2 , respectively …”

Cobalt(II) Complexes Based on Benzylmalonate Anions Exhibiting Field-Induced Single-Ion Magnet Slow Relaxation Behavior

“…Cobalt coordination complexes exhibit redox [1,2], optical [3,4], and magnetic [5,6] properties that can be attractive for application in catalysis [7,8], biology, and medicine [9,10]. The magnetic behavior of cobalt(II) ions depends on the coordination environment, crystal field, and interaction with nearby paramagnetic ions [11].…”

CoIIComplexes with a Tripyridine Ligand, Containing a 2,6-Di-tert-butylphenolic Fragment: Synthesis, Structure, and Formation of Stable Radicals

“…Coordination polymers are considered as the basis for creation of new sorbents, catalysts, and luminescent and magnetic materials. 1−5 The specific feature of such systems is their capacity to combine several physical properties, which can find application in practice, such as nontrivial magnetism and luminescence, 6−8 catalytic activity along with the ability to adsorb certain substrates, 9−11 and the ability to change the physical property upon interaction with different compounds 7,12,13 or action of external factors (irradiation, pressure, etc.). 14−17 For creation of materials with tunable properties, metal–radical complexes are promising objects because free radical generation or disappearance can make significant influence on electric conductivity 18,19 and can be an instrument for luminescence control.…”

“…Coordination polymers are considered as the basis for creation of new sorbents, catalysts, and luminescent and magnetic materials. − The specific feature of such systems is their capacity to combine several physical properties, which can find application in practice, such as nontrivial magnetism and luminescence, − catalytic activity along with the ability to adsorb certain substrates, − and the ability to change the physical property upon interaction with different compounds ,, or action of external factors (irradiation, pressure, etc. ). − For creation of materials with tunable properties, metal–radical complexes are promising objects because free radical generation or disappearance can make significant influence on electric conductivity , and can be an instrument for luminescence control. − In addition, unique spin transitions were found in transition metal complexes with free radicals, which resembled spin-crossover and were caused by rearrangement of the crystal structure at certain temperature. , Thus, studies of the structure and physical and chemical properties of the transition metal compounds with stable free radicals are an actual task of modern inorganic and physical chemistry, as well as materials science.…”