Synthesis and Crystal Structure of a Heptanuclear and an Octanuclear Copper(II) Complex Derived from α-D-Glucofuranoses

Self-Assembly of Antiferromagnetically-Coupled Copper(II) Supramolecular Architectures with Diverse Structural Complexities

The self-assembly of 2,6-diformyl-4-methylphenol (DFMP) and 1-amino-2-propanol (AP)/2-amino-1,3-propanediol (APD) in the presence of copper(II) ions results in the formation of six new supramolecular architectures containing two versatile double Schiff base ligands (H₃L and H₅L1) with one-, two-, or three-dimensional structures involving diverse nuclearities: tetranuclear [Cu₄(HL²⁻)₂(N₃)₄]·4CH₃OH·56H₂O (1) and [Cu₄(L³⁻)₂(OH)₂(H₂O)₂] (2), dinuclear [Cu₂(H₃L1²⁻)(N₃)(H₂O)(NO₃)] (3), polynuclear {[Cu₂(H₃L1²⁻)(H₂O)(BF₄)(N₃)]·H₂O}_n (4), heptanuclear [Cu₇(H₃L1²⁻)₂(O)₂(C₆H₅CO₂)₆]·6CH₃OH·44H₂O (5), and decanuclear [Cu₁₀(H₃L1²⁻)₄(O)₂(OH)₂(C₆H₅CO₂)₄] (C₆H₅CO₂)₂·20H₂O (6). X-ray studies have revealed that the basic building block in 1, 3, and 4 is comprised of two copper centers bridged through one μ-phenolate oxygen atom from HL²⁻ or H₃L1²⁻, and one μ-1,1-azido (N₃⁻) ion and in 2, 5, and 6 by μ-phenoxide oxygen of L³⁻ or H₃L1²⁻ and μ-O²⁻ or μ₃-O²⁻ ions. H-bonding involving coordinated/uncoordinated hydroxy groups of the ligands generates fascinating supramolecular architectures with 1D-single chains (1 and 6), 2D-sheets (3), and 3D-structures (4). In 5, benzoate ions display four different coordination modes, which, in our opinion, is unprecedented and constitutes a new discovery. In 1, 3, and 5, Cu(II) ions in [Cu₂] units are antiferromagnetically coupled, with J ranging from −177 to −278 cm⁻¹.

Stabilization of Cu7 clusters in azide networks: syntheses, structures and magnetic behaviour

Two new azide bridged copper(II) coordination polymer compounds, [Cu7(N3)14(C3H10N2)(C4H13N3)]n (I) and [Cu7(N3)14(C3H10N2)(C5H15N3)2]n (II) [where C3H10N2 = 1,2-diaminopropane (1,2-DAP); C4H13N3 = diethylenetriamine (DETA); C5H15N3 = N-2-aminoethyl-1,3-propanediamine (AEDAP)] were prepared by employing a room temperature diffusion technique involving three layers. Single crystal studies reveal that both compounds I and II, have similar connectivity forming Cu7 clusters through end-on (EO) bonding of the azide. The Cu7 clusters are connected through end-to-end (EE) connectivity of the azides forming three-dimensional structures. Magnetic studies confirmed the ferromagnetic interactions within the Cu7 units and revealed the occurrence of concomitant ferro- and antiferro-magnetic interactions between these clusters. As a result I behaves as a weak-ferromagnet with TC = 10 K.

Prospects of metal complexes peripherally substituted with sugars in biomedicinal applications

Metal complexes possess unique tunable properties, such as radioactivity, cytotoxicity or photophysical features, enabling them to act as diagnostic tracers or therapeutic agents. In applying them in biological systems, it is often necessary to enhance their solubility and biocompatibility. To achieve such goals, like the targeting of binding domains, transport systems and enzyme activities, the attachment of carbohydrate moieties appears to be suitable. Sugar-substitution in the periphery of metal complexes has therefore become a strongly growing field of research. Outlined herein is a selection of recent examples.