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The potential use of bis(methylene)bis(5-bromo-2-hydroxylsalicyloylhydrazone) as a multifunctional fluorescence sensor for Cu2+, Ni2+, Co2+ and Fe2+ ions was investigated. The optical behaviour shows an increase in an absorption band at 408 nm which can be ascribed to the d–d transition (UV-vis) of the metal ions and a concomitant decrease in fluorescence intensity at 507 nm. The crystallographic analysis shows the binding site of the sensor to two Cu2+ ions and confirms the stoichiometry of 1 : 2 (ligand to metal) which is in good agreement with a Job plot analysis. Furthermore the Cu2+-complex catalyses A3 coupling reactions at 1 mol% catalytic loading; chiral propargylamine derivatives were obtained in high yield after 24 h reaction time under ambient conditions.

The purpose of the present contribution is to illustrate how to design and grow crystals of POMOFs based on POM-hybrid linkers with lanthanide ions as nodes. Thus, the Mn$^{III}$-centered Anderson���Evans polyoxometalate (Mn-A-E-POM) was functionalized with 4-(((1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)amino)methyl)benzoic acid (H$_{4}^{-}$L) to afford the hybrid inorganic���organic POM [N(n-C$_{4}$H$_{9}$)$_{4}$]$_{4}$[(MnMo$_{6}$O$_{18}$)(HL)(L)] (1), which in turn reacts with lanthanide salts and yields two three-dimensional frameworks with the general formulas Ln(DMF)$_{6}$Ln(DMF)$_{5}$Ln$_{3}$(DMF)$_{10}$[(MnMo$_{6}$O$_{18}$)(L)$_{2}$]$_{3}$��xDMF (2; Ln = La���Nd) and [Ln(DMF)4(H2O)]2[Ln3(DMF)6][(MnMo6O18)(L)2]3��xDMF (3; Ln = Y, Sm���Lu). The differentiation in these two families results from the lanthanide contraction. The crystallization process is crucial for obtaining these two families in a bulk pure phase. Family 2 can be obtained by stirring, while for family 3 the less energy demanding layering method proved to be the most efficient pathway. Notably, the change in the ionic radii causes a change in space group (from P2$_{1}$ (family 2) to P2$_{1}$/c (family 3); however, the topology of the frameworks is unaffected.

We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6-bis((E)-1-(2-(pyridin-2-yl)-hydrazineylidene)ethyl)pyridine (H2dapp) [Dy(H2dapp)(NO3)2]NO3 (1), [Dy(H2dapp)(OAc)2]Cl (2) and [Dy(H2dapp)(NO3)2]Cl0.92(NO3)0.08 (3). The (H2dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N−H group of the (H2dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds1 and 2 is the presence of short nitrate-nitrate intermolecular ligand contact opening further lattice relaxation pathways.

The goal of this study was to design a ligand system which can accommodate single lanthanide(III)-ions and investigate the properties of the resulting complexes. The complexes of all the accesible lanthanides and yttrium with the new ligand LH6 = N,N′-dimethyl-N,N′-ethylene-bis(5-bromo-3-(1H-benzimidazol-2-yl)hydrazineylidene)-2-hydroxybenzylamine) were obtained in high yield at room temperature under aerobic reaction conditions. The corresponding compounds were characterised using X-ray diffraction, FT-IR, elemental analysis and the optical properties of all complexes were investigated using UV-vis and fluorescence spectroscopy. The air stable complexes efficiently transform biomass furfural to trans-4,5-cyclopentenones in high yield.

We present the synthesis and characterization of heterometallic compounds with a very large azide to metal ratio. Their interesting structures give rise to fascinating magnetic properties.