A tetrameric uudd type water cluster encapsulated in a dinuclear vanadium(V) Schiff base complex and its role in the formation of supramolecular assemblies: A joint experimental and theoretical study

Vanadium complexes as potential metal-based antimicrobial drugs

Radical increase of antibiotic resistance among microbes has become a serious problem for clinics all over the world that has led to the need for search of novel types of antimicrobial drugs. Each year, researchers synthesize a multitude of compounds in pursuit of identifying potential chemotherapeutic agents through diverse methodological evaluations. Among the vast array of biologically significant compounds, coordination compounds exhibit a broad range of activities within biological systems. Chelation, in particular, induces significant alterations in the biological properties of ligands and the metal component, contributing to their efficacy. Chelation increases the lipophilicity of metal complexes as a result of which they are easily absorbed by the microorganisms, thus leading to their easy passage across cell membrane. The research and development in the field of metallodrugs can be advantageous to overcome the problem encountered in antibiotic resistance. The multifaceted involvement of vanadium relative to other biometals within biological systems, coupled with its comparatively lower toxicity, underscores its utility in the advancement of novel metal-based therapeutic agents. This review aims to delineate the biological significance of V(V/IV/III) complexes as antimicrobial agents. The amassed data indicate a correlation between the potency of vanadium complexes as antimicrobial agents and the oxidation state of the metal, with III being the least toxic and V representing the most toxic oxidation state of vanadium.

Large interaction energy for the homodimer and the heterodimer extracted from the supramolecular chain of a bent trinuclear zinc(ii) complex with a reduced Schiff base ligand

The coordinated amino groups in a trinuclear zinc complex participate in strong H-bonding interactions that have been analysed. The dimerization energy is very large for both the homodimer and the heterodimer in the 1D supramolecular chain.

Synthesis and crystal structure of catena-poly[[hexa-aqua{μ3-2-[bis-(carboxyl-atometh-yl)amino]-terephthalato}dicobalt(II)] penta-hydrate] containing water tapes and penta-mers

The title coordination polymer, {[Co2(C12H7NO8)(H2O)6]·5H2O} n , was crystallized at room temperature from an aqueous solution of 2-aminodi-acetic terephthalic acid (H4adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp4- ligand, one and two half CoII ions, six water ligands coordinated to CoII ions and five uncoordinated water mol-ecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octa-hedral O2(OH2)4 environments, whereas the other adopts a slightly distorted octa-hedral NO3(OH2)2 environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co2(C12H7NO8)(H2O)6]} n , which assemble into a three-dimensional supra-molecular architecture via networks of hydrogen bonds involving the coordinated and free water mol-ecules. One-dimensional 'water tapes' are formed, containing alternating six-membered and twelve-membered rings of water mol-ecules, together with water penta-mers, in which a central uncoordinated water mol-ecule is hydrogen bonded to two coordinated and two free water mol-ecules in a tetra-hedral arrangement.

Stabilization of Near Identical Hydrogen Bonded Octameric Water Clusters in Crystal Structures of Three Distinct Non-Charged Polyamide Macrocyclic Host Molecules

In this paper, we present a comparative analysis of the solid state structures of three well-resolved hydrates of macrocyclic host molecules 1a, 1b, and 2 containing an intrannular amide-aryl substituent (lariat arm) connected to a fixed 26-membered ring in a normal (-NHCOAr, hosts 1a and 1b) or reverse manner (-CONHAr, host 2). Despite different chemical structures, these hosts crystallize as isostructural tetrahydrates in the same P-1 space group. Moreover, their crystals exhibit identical hydrogen bond motifs resulting in a stabilization of an almost identical unusual octameric water cluster built from the cyclic tetramer core and four water molecules, attached sequentially in an "up-and-down" manner. Further analysis reveals that, among the series, the structure of host 2 provides the most suitable environment for the accommodation of this type of water cluster.