Mechanochemical Synthesis of 3d Transition-Metal-1,2,4-Triazole Complexes as Precursors for Microwave-Assisted and Thermal Conversion to Coordination Polymers with a High Influence on the Dielectric Properties

The complexes [MCl2 (TzH)4] (M=Mn (1), Fe (2); TzH=1,2,4-1H-triazole) and [ZnCl2 (TzH)2] (3) have been obtained by mechanochemical reactions of the corresponding divalent metal chloride and 1,2,4-1H-triazole. They were successfully used as precursors for the formation of coordination polymers either by a microwave-assisted reaction or by thermal conversion. For manganese, the conversion directly yielded 1∞ [MnCl2 TzH] (4), whereas for the iron-containing precursor, 1∞ [FeCl2 TzH] (6), was formed via the intermediate coordination polymer 1∞ [FeCl(TzH)2]Cl (5). For cobalt, the isotypic polymer 1∞ [CoCl(TzH)2]Cl (7) was obtained, but exclusively by a microwave-induced reaction directly from CoCl2 . The crystal structures were resolved from single crystals and powders. The dielectric properties were determined and revealed large differences in permittivity between the precursor complexes and the rigid chain-like coordination polymers. Whereas the monomeric complexes exhibit very different dielectric behaviour, depending on the transition metal, from "low-k" to "high-k" with the permittivity ranging from 4.3 to >100 for frequencies of up to 1000 Hz, the coordination polymers and complexes with strong intermolecular interactions are all close to "low-k" materials with very low dielectric constants up to 50 °C. Therefore, the conversion procedures can be used to deliberately influence the dielectric properties from complex to polymer and for different 3d transition-metal ions.

N-donor ligands enhancing luminescence properties of seven Zn/Cd(ii) MOFs based on a large rigid π-conjugated carboxylate ligand

Aggregation-induced emission (AIE) has been identified and studied based on a bulky π-conjugated ligand (H₂IDPA) with Zn/Cd^II metals.

Assembly of noncentrosymmetric coordination polymers by the integration of acentric Ba(ii)/Sr(ii) and Li(i) coordination polyhedra

Presented is a strategy to construct noncentrosymmetric CPs through the integration of acentric [LiO_xN_4−x] and [BaO_xN_y] coordination polyhedraviabridging organic ligands.

Magnetic and luminescent properties of lanthanide coordination polymers with asymmetric biphenyl-3,2′,5′-tricarboxylate

An asymmetric ligand was employed to construct eight (3,6)-connected lanthanide complexes exhibiting slow magnetization relaxation behaviour and characteristic luminescent properties.

Tuned synthesis of two coordination polymers of Cd(ii) using substituted bent 3-pyridyl linker and succinate: structures and their applications in anion exchange and sorption properties

Two new coordination polymers of Cd(ii) have been synthesized using disodium succinate and a substituted bent N,N'-donor ligand where the substitution on N,N'-donor ligand controlled the formation of the product.

A two-dimensional Cd(II) coordination polymer with 2,2'-(disulfanediyl)dibenzoate and 1,10-phenanthroline ligands

In poly[[μ3-2,2'-(disulfanediyl)dibenzoato-κ(5)O:O,O':O'',O'''](1,10-phenanthroline-κ(2)N,N')cadmium(II)], [Cd(C14H8O4S2)(C12H8N2)]n, the asymmetric unit contains one Cd(II) cation, one 2,2'-(disulfanediyl)dibenzoate anion (denoted dtdb(2-)) and one 1,10-phenanthroline ligand (denoted phen). Each Cd(II) centre is seven-coordinated by five O atoms of bridging/chelating carboxylate groups from three dtdb(2-) ligands and by two N atoms from one phen ligand, forming a distorted pentagonal-bipyramidal geometry. The Cd(II) cations are bridged by dtdb(2-) anions to give a two-dimensional (4,4) layer. The layers are stacked to generate a three-dimensional supramolecular architecture via a combination of aromatic C-H···π and π-π interactions. The thermogravimetric and luminescence properties of this compound were also investigated.

Eu@COK-16, a host sensitized, hybrid luminescent metal–organic framework

Host sensitized Eu@COK-16 demonstrates a novel strategy for material design combining the advantages of luminescent MOFs with those of luminescent host–guest materials.

Structures and properties of coordination polymers involving asymmetric biphenyl-3,2′,5′-tricarboxylate

The conformation stability and coordination modes of an asymmetric polycarboxylate ligand (H₃bptc) and the properties of its compounds have been investigated.