Coordination Architectures of Lanthanum Complexes Based on Bifunctional 5-Substituted Tetrazolecarboxylate Ligands

Bifunctional tetrazole-carboxylate ligand based Zn(ii) complexes: synthesis and their excellent potential anticancer properties

Transition metal coordination complexes have provided cancer treatment with new insights to overcome the limitations of current chemotherapeutic agents. Utilization of bifunctional tetrazole-carboxylate ligands with Zn(ii) obtained two self-assembled complexes [Zn(HL¹)(bipy)_3/2(H₂O)]·CH₃OH·4(H₂O) (1) (H₃L¹ = 1,3,5-tri(2-carboxymethyltetrazol-5-yl) benzene) and [Zn(L²)₂(H₂O)₂]₂·2H₂O (2) (HL² = (5-pyridin-3-yl-tetrazol-2-yl)-acetic acid). The X-ray diffraction results showed that the two complexes displayed a two-dimensional (2D) layer structure and a one-dimensional (1D) layer structure. Nanocoprecipitation with DSPE-PEG-2000 resulted in the formation of complex nanoparticles (NPS) with excellent water dispersion. In vitro CCK-8 assay indicated the two NPs exert high cytotoxicity and sensitivity and a low half-maximum inhibitory concentration (IC₅₀) towards HeLa than HepG2 cells. In addition, the cytotoxicity was also confirmed by live/dead co-stained experiments. The presented experimental results showed the 1 and 2 NPs were capable of inhibiting cell proliferation in vitro and may help design coordination complex-based anticancer candidates for cancer cells.

Ba-MOFs with tetrazole-based acetic acids: unusual configuration, novel topology and high proton conductivity

Metal-organic frameworks (MOFs) as proton-conductive materials have attracted increasing attention due to their applications in proton-exchange membrane fuel cells. While the majority of the MOFs are based on transition metals, group II metals with unusual configurations have received relatively less attention. In this work, we selected three tetrazole-based acetic acids, N,N-di(2-carboxymethyltetrazol-5-yl)amine (H₂L¹), 1,3,5-tri(2-carboxymethyltetrazol-5-yl)benzene (H₃L²), and 4,5-di(tetrazol-5-yl)imidazolylacetic acid (H₃L³), as ligands and prepared three MOFs with barium(ii) ions: [Ba₂(L¹)₂(H₂O)₅]·2H₂O (1), (Me₂NH₂)[Ba(L²)(H₂O)]·3H₂O (2), and [Ba₃(μ₂-H₂O)(L³)₂(H₂O)₃]·2H₂O (3). Ba-MOFs have been unambiguously characterized by elemental, FT-IR spectroscopy and single-crystal X-ray diffraction analyses. In the solid state, 2D MOF 1 with two nine-coordinated Ba(ii) centers shows a rare hula hoop-like geometry at the Ba1 atom and a distorted tricapped trigonal prismatic geometry around the Ba2 one. Unusual sphenocorona geometry is also found in MOF 2 with a ten-coordinated Ba(ii) ion. In MOF 3, three different Ba(ii) ions coexist with two nine-coordinated Ba1 and Ba2 displaying a muffin-like configuration and a distorted tricapped trigonal prism geometry, respectively, and an eight-coordinated Ba3 having a distorted biaugmented trigonal prism geometry. In addition, MOF 2 exhibits an unprecedented trinodal 3,7,7-connected 3D network with the Schläfli symbol (3⁷·4⁶·5²·6²·7⁴)(3⁷·4⁶·5²·6³·7³)₂(6³) and MOF 3 displays a novel trinodal 4,5,9-connected 3D framework with the Schläfli symbol (4²¹·6¹⁵)(4⁵·6)(4⁸·6²). Due to the presence of extensive hydrogen bonded networks consisting of dimethyl ammonium and water molecules in the 1D channels, MOF 2 shows a high proton conductivity of 4.47 × 10^-3 S cm^-1 at 85 °C and 98% relative humidity (RH).

A Surface Coordination Interphase Stabilizes a Solid-State Battery

Solid-state electrolytes (SSEs) show potential in addressing the safety issues of liquid batteries, but the poor interface contact between them and the electrodes hinders practical applications. Here, coordination chemistry of nitrile groups based on succinonitrile (SCN) and polyacrylonitrile (PAN) is studied on the surface of Li_6.4 La₃ Zr_1.4 Ta_0.6 O₁₂ (LLZTO) SSE to build the chemical bonded electrolyte/electrode interfaces. The coordination of the nitrile group and LLZTO is clarified. A deformable PAN-modifying SCN electrolyte (PSE) interphase with stable ionic conductivity (10^-4  S cm^-1 ) and high lithium-ion transference number (0.66) is fabricated on the surface of LLZTO electrolyte based on the coordination competition of nitrile groups. Once applied to SSBs, it endows low interface resistance and strong bonding for the electrolyte/electrode interfaces so that the initial Coulomb efficiency reaches 95.6 % and the capacity remains 99 % after 250 cycles at 25 °C.