Inorganics, Volume 9, Issue 1 (January 2021) – 8 articles

An overview is presented of the crystal structures of transition metal, main group element, and lanthanide compounds containing poly-functional dithiocarbamate ligands, namely species containing two or more connected NCS₂⁻ residues. In all, there are 40 different ligands of this type that have been characterised crystallographically in their heavy-element compounds with up to six NCS₂⁻ residues; all are bridging. In most cases, the resulting aggregates are zero-dimensional, often di-nuclear, but aggregates of up to 36 metal (gold) atoms are noted. There are smaller numbers of one-, two-, and three-dimensional architectures sustained by poly-functional dithiocarbamate ligands in their respective crystals. The survey highlights the opportunities afforded by this generally under-studied class of ligand. Full article

Following the “Molybdenum and Tungsten Enzyme conference—MoTEC2019” and the satellite meeting on “Iron–Sulfur for Life”, we wanted to emphasize the link between iron–sulfur clusters and their importance for the biosynthesis, assembly, and activity of complex metalloenzymes in this Special Issue of Inorganics, entitled “Transition Metals in Catalysis: The Functional Relationship of Fe–S Clusters and Molybdenum or Tungsten Cofactor-Containing Enzyme Systems” [...] Full article

Breast cancer stem cells (CSCs) are a sub-population of tumour cells that can promote breast cancer relapse and metastasis. Current treatments are unable to completely remove breast CSCs, therefore it is essential to develop new chemotherapeutics that can remove breast CSCs at clinically compatible doses. Here we present the synthesis, characterisation, and anti-breast CSC properties of copper(II) complexes, [Cu(L²)(1,10-phenanthroline)]PF₆ (2) and [Cu(L³)(1,10-phenanthroline)]PF₆ (3) comprising of a tridentate (O,N,S) coordinated naphthol Schiff base ligand (L² = (E)-1-(((2-(methylthio)ethyl)imino)methyl)naphthalen-2-ol or L³ = (E)-1-(((2-(ethylthio)ethyl)imino)methyl)naphthalen-2-ol and 1,10-phenanthroline. The copper(II) complexes (2 and 3) kill breast CSCs, cultured in monolayer and three-dimensional systems, in the micromolar range. Notably, 2 and 3 are more potent towards breast CSC mammospheres than salinomycin (up to 4.5-fold), an established anti-breast CSC agent. Further, cell-based studies indicate that 2 and 3 are readily taken up by breast CSCs and elevate intracellular reactive oxygen species (ROS) levels upon short exposure times (0.5–1 h). The latter is likely to be the underlying mechanism by which 2 and 3 induces breast CSC death. Full article

The synthesis of new porous materials with desired properties is a challenging task. It becomes especially difficult if you need to combine several metals in one framework to obtain a heterometallic node. The use of presynthesized complexes for obtaining of new heterometallic metal–organic frameworks could be essential to solve the problem of tailored synthesis. In our study we use presynthesized heterometallic pivalate complex [Li₂Zn₂(piv)₆(py)₂] to obtain new MOFs with heterometallic core as a node of the framework. We are managed to obtain four new heterometallic MOFs: [H₂N(CH₃)₂]₂[Li₂Zn₂(bdc)₄]·CH₃CN·DMF (1), [Li₂Zn₂(H₂Br₂-bdc)(Br₂-bdc)₃]·2DMF (2), [H₂N(CH₃)₂][LiZn₂(ndc)₃]·CH₃CN (3) and [{Li₂Zn₂(dmf)(py)₂}{LiZn(dmf)₂}₂ (NO₂-bdc)₆]·5DMF (4). Moreover three of them contain starting tetranuclear core {Li₂Zn₂} and saves its geometry. We also demonstrate the influence of substituent in terephthalate ring on preservation of tetranuclear core. For compound 1 it was shown that luminescence of the framework could be quenched when nitrobenzene is included in the pores. Full article

Poly(lactic acid) (PLA)/palygorskite (Paly) nanocomposites were prepared using the melt compounding technique. Paly modified by 3-aminopropyltriethoxysilane (APTES) and vinyltrimethoxysilane (VTMS) was used as nanofiller for PLA with concentrations in the 1–7 wt% range. It has been found that the functionalization allows a covalent bond between the hydroxyl groups of the Paly and the PLA matrix, evidenced by the improvement in mechanical properties. Paly modification with VTMS has better properties compared with Pale modification with APTES. This indicates a better adhesion between the Paly-VTMS and PLA matrix, and a good dispersion of the nanofiller in the polymer matrix. Full article

Nanoconfinement is an effective strategy to tune the properties of the metal hydrides. It has been extensively employed to modify the ionic conductivity of LiBH₄ as an electrolyte for Li-ion batteries. However, the approach does not seem to be applicable to other borohydrides such as NaBH₄, which is found to reach a limited improvement in ionic conductivity of 10⁻⁷ S cm⁻¹ at 115 °C upon nanoconfinement in Mobil Composition of Matter No. 41 (MCM-41) instead of 10⁻⁸ S cm⁻¹. In comparison, introducing large cage anions in the form of Na₂B₁₂H₁₂ naturally formed upon the nanoconfinement of NaBH₄ was found to be more effective in leading to higher ionic conductivities of 10⁻⁴ S cm⁻¹ at 110 °C. Full article

The adsorption of benzene, toluene, ethylbenzene, and xylene isomers, also known as BTEX, from the gas phase into porous thin films of the metal–organic framework UiO-66-X, where X = H, NH₂, and NO₂, was measured to quantify adsorption capacity. The thin films were grown by a vapor-conversion method onto Au-coated quartz microbalance crystals. The MOF thin films were characterized by IR and Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The thin films were activated by heating under high vacuum and exposed to each gas to calculate the Henry’s constant. The results demonstrate that the functional groups in the organic linker and missing-linkers both play important roles in the adsorption capacity. Several trends can be observed in the data. First, all the compounds in the BTEX family have lower Henry’s constants in the UiO-66-H films compared to the UiO-66-NH₂ and UiO-66-NO₂ films, which can largely be attributed to the absence of a functional group on the linker. Second, at 25 °C, the Henry’s constants for all the BTEX compounds in UiO-66-NO₂ films are larger than UiO-66-NH₂ films. Third, the role of missing linkers is addressed by comparing the measured adsorption capacity to ideal pore filling. The results show that the UiO-66-H films are the most defect-free and the UiO-66-NO₂ films have the most missing linker defects. Full article