Solid-State Structural Transformation and Photoluminescence Properties of Supramolecular Coordination Compounds

The combination of strong coordination bonds and hydrogen bonding interactions were used to generate a series of supramolecular coordination materials (SCMs), which was achieved by reacting a bis-pyridyl amide ligand, namely N-(4-pyridyl)nicotinamide (4PNA) with copper(II), zinc(II), and cadmium(II) benzoates. The SCMs were structurally characterized using X-ray diffraction and the key intermolecular interactions were identified via Hirshfeld surface analysis. The role of solvent molecules on the supramolecular architecture was analyzed by synthesizing the SCMs in different solvents/solvent mixtures. A solvent-mediated solid-state structural transformation was observed in copper(II) SCMs and we were able to isolate the intermediate form of the crystal-to-crystal transformation process. The luminescence experiments revealed that complexation enhanced the fluorescence properties of 4PNA in the zinc(II) and cadmium(II) SCMs, but a reverse phenomenon was observed in the copper(II) SCMs. This work demonstrated the tuning of supramolecular assembly in coordination compounds as a function of solvents for generating SCMs with diverse properties.

Polyoxometalate-based metal–organic frameworks for heterogeneous catalysis

POM-based MOFs simultaneously possessing the virtues of POMs and MOFs exhibit excellent heterogeneous catalytic properties.

Syntheses, structures and catalytic properties of Evans–Showell-type polyoxometalate-based 3D metal–organic complexes constructed from the semi-rigid bis(pyridylformyl)piperazine ligand and transition metals

Two 3D Evans–Showell-type POM-based different transition metals–bis-pyrazine–bis-amide complexes act as heterogeneous catalysts for the oxidation of benzyl alcohol.

Three novel and various isopolymolybdate-based hybrids built from the carboxyl oxygen atoms of in situ ligands: substituent-tuned assembly, architectures and properties

Three isopolyoxometalate-based hybrids assembled from in-situ generated ligands reveal that the N-donor groups of ligands may play key roles in the self-assembling process and various structures of the title compounds.

Influence of pendant 2-[1,2,4]triazol-4-yl-ethylamine and symmetrical bis(pyrazol) ligands on dimensional extension of POM-based compounds

By using pendant tea and bis(pyrazole) ligands H₂bdpm and H₂bhpe, five new Mo₈-based compounds have been synthesized. The tea induces low dimensional subunits of 1–3, while the H₂bdpm and H₂bhpe ligands induce high dimensional structures of 4 and 5.

A series of Keggin-based compounds constructed by conjugate ring-rich pyrazine and quinoxaline derivatives

Ligands L¹ and L² are utilized in POM chemistry for the first time. Different Keggin anions induce distinct 2D structures of compounds 1/2 and 3/4 in Ag–L¹ and Ag–L² systems, respectively. By adding Ag^I and Cu^I to the PMo₁₂–L² system different 3 and 5 were formed.