Constantinos G. Efthymiou

A high-nuclearity 3d/4f metal oxime cluster: an unusual Ni(8)Dy(8) "core-shell" complex from the use of 2-pyridinealdoxime.

The initial employment of 2-pyridinealdoxime in 3d/4f chemistry has led to a Ni(II)(8)Dy(III)(8) cluster with an unprecedented metal topology; the compound has an unusual structure, is the highest-nuclearity metal oxime cluster to date, and exhibits slow magnetization relaxation.

In search of 3d/4f-metal single-molecule magnets: Nickel(II)/lanthanide(III) coordination clusters

The importance of 3d/4f-metal cluster chemistry is outlined, and the employment of 2-pyridyl ketone- and 2-pyridyl oxime-based ligands for the preparation of low-nuclearity NiII/LnIII complexes (Ln = lanthanide) is reviewed. The synthetic utility of the “metal complexes as ligands” and “one-pot” approaches is critically discussed. The small nuclearity of the products permits the in-depth analysis of their magnetic properties.

Flexible lanthanide MOFs as highly selective and reusable liquid MeOH sorbents

A series of new 3-D Ln3+ metal–organic frameworks (MOFs), which are based on the semi-rigid ligand H3CIP [H3CIP = 5-(4-carboxybenzylideneamino)isophthalic acid], [Ln2(CIP)2(DMF)4−x(H2O)x] (Ln3+ = La3+, Ce3+, Pr3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+; x = 0–2) are reported. Magnetic susceptibility data for selected compounds indicated the presence of antiferromagnetic interactions, while the photoluminescence properties of the MOFs revealed emission peaks that are red-shifted compared to the emission (405 nm) of the uncoordinated H3CIP ligand, whereas the Eu3+ and Tb3+ analogues showed emission peaks typical of these lanthanide ions. Single-Crystal-to-Single-Crystal (SCSC) coordinating solvent exchange experiments with acetone and methanol for the Ce3+ analogue afforded compounds that are isostructural with the pristine material and contain one acetone and one water or 1.25 methanol and 0.75 water ligated molecules per Ce3+ respectively. The capability of activated Ce3+ MOF to absorb liquid MeOH was evaluated by means of 1H NMR spectroscopy. The results of the sorption experiments indicated a maximum absorption capacity of 96(2) mg g−1 and fast kinetics, while the sorbent is reusable and is also capable of highly selective sorption of MeOH over EtOH. Overall this work emphasizes the multifunctional nature of lanthanide MOFs and provides insight into the liquid-phase sorption of small organic molecules by such materials demonstrating their high potential as sorbents.

Synthesis and Structural Characterization of a New Tetranuclear Nickel(II) Sulfato Complex Containing the Anionic Form of Di-2-Pyridyl Ketone Oxime

The preparation and crystal structure of a tetranuclear Ni(II) sulfato cluster containing the anion of di-2-pyridyl ketone oxime, (py) 2CNO −, are reported. Treatment of NiSO 4·6H 2O with one equivalent of (py) 2CNOH and one equivalent of NEt 3 in MeOH leads to the compound [Ni 4{(py) 2CNO} 4(SO 4) 2(MeOH) 4] ( 1) in moderate yield. The metal ions are linked together by two 3.2111 and two 2.1110 (Harris notation) (py) 2CNO − ligands, as well as two 2.1100 SO 4 2− ions to create a rare metallacrown-type (12-MC-4) ring. Strong H-bond intermolecular interactions in 1 lead to the formation of a 1D chain along the 𝑐 axis. Characteristic IR bands are discussed in terms of the known structure of 1.

Mononuclear and Dinuclear Manganese(II) Complexes from the Use of Methyl(2-pyridyl)ketone Oxime

The reactions of methyl(2-pyridyl)ketone oxime, (py)C(Me)NOH, with manganese(II) sulfate monohydrate have been investigated. The reaction between equimolar quantities of MnSO4 · H2O and (py)C(Me)NOH in H2O lead to the dinuclear complex [Mn2(SO4)2{(py)C(Me)NOH}4] · (py)C(Me)NOH, 1 · (py)C(Me)NOH, while employment of NaOMe as base affords the compound [Mn(HCO2)2{(py)C(Me)NOH}2] (2). The structures of both compounds have been determined by single crystal X-ray diffraction. In both complexes, the organic ligand chelates through its nitrogen atoms. The IR data are discussed in terms of the nature of bonding and the structures of the two complexes.