Generation of well-defined potential metallotherapeutics for cancer treatment, one of the most population-threatening diseases, is challenging and an active area of modern research in view of their unique properties and thus multiple possible pathways of action in cells. Specifically, Schiff base ligands were recognized as very promising building blocks for the construction of stable and active complexes of numerous geometries and topologies. Incorporation of Ag(I) ions allows for the formation of flat complexes with potential unoccupied coordination sites, thus giving rise to specific interactions between the metallotherapeutic and biomolecule of interest. Herein, we present the design, synthesis and characterization of new Schiff base ligand L and its Ag(I) bimetallic complex [Ag₂L₂]²⁺ with two planar moieties formed around the metal ions and connected through cyclohexane rings, confirmed by X-ray measurements. The compounds were described in context of their potential use as anticancer drugs through DNA and BSA binding pathways by several spectroscopic methods (CD, UV-Vis, fluorescence). We revealed that both, L and [Ag₂L₂]²⁺, interact with similar affinity with CT-DNA (K_b~10⁶ M⁻¹), while they differ in the type and strength of interactions with the model albumin–BSA. [Ag₂L₂]²⁺ binds BSA in both a dynamic and static manner with the K_sv = 8.8 × 10⁴ M⁻¹ in the Trp-134 and Trp-213 sites, whereas L interacts with BSA only dynamically (K_SV = 2.4 × 10⁴ M⁻¹). This found further confirmation in the CD studies which revealed a reduction in α-helix content in the albumin of 16% in presence of [Ag₂L₂]²⁺.

Elucidation of the structure and function of biomolecules provides us knowledge that can be transferred into the generation of new materials and eventually applications in e.g., catalysis or bioassays. The main problems, however, concern the complexity of the natural systems and their limited availability, which necessitates utilization of simple biomimetic analogues that are, to a certain degree, similar in terms of structure and thus behaviour. We have, therefore, devised a small library of six tridentate N-heterocyclic coordinating agents (L¹–L⁶), which, upon complexation, form two groups of artificial, monometallic non-heme iron species. Utilization of iron(III) chloride leads to the formation of the 1:1 (Fe:L_n) ‘open’ complexes, whereas iron(II) trifluoromethanosulfonate allows for the synthesis of 1:2 (M:L_n) ‘closed’ systems. The structural differences between the individual complexes are a result of the information encoded within the metallic centre and the chosen counterion, whereas the organic scaffold influences the observed properties. Indeed, the number and nature of the external hydrogen bond donors coming from the presence of (benz)imidazole moieties in the ligand framework are responsible for the observed biological behaviour in terms of mimicking phenoxazinone synthase activity and interaction with DNA.

Generation of well-defined organic–inorganic hybrid materials with controllable size and morphology is challenging and an active area of modern research in view of their unique properties and thus multifunctional applications. Specifically polyoxometalates (POMs) were recognized as a very promising group for the construction of those systems, nonetheless there are domains where the profound understanding of hierarchical mutual interactions and assembly are lacking. We present an efficient approach towards the synthesis of a novel group of POM-based nanocomposites that we name Complex-Decorated Surfactant Encapsulated-Clusters (CD-SECs). In the investigated system the organic surfactant may behave as a metal-coordinating agent, thus allowing for derivatization of the synthesized SECs via utilization of the non-covalent interactions. We demonstrate possibilities and limitations of three types of hybrid systems (H1–H3) generated via seven distinct constructing approaches (routes A–G). These systems have the potential to exhibit multiresponsive functions depending on the nature of their building blocks and could find many potential applications in biology or materials science.

The present work reports the synthesis of new N4-donor compounds carrying p-xylyl spacers in their structure. Different Schiff base aliphatic N-donors were obtained synthetically and subsequently evaluated for their ability to interact with two models of nucleic acids: calf-thymus DNA (CT-DNA) and the RNA from yeast Saccharomyces cerevisiae (herein simply indicated as RNA). In more detail, by condensing p-xylylenediamine and a series of aldehydes, we obtained the following Schiff base ligands: 2-thiazolecarboxaldehyde (L1), pyridine-2-carboxaldehyde (L2), 5-methylisoxazole-3-carboxaldehyde (L3), 1-methyl-2-imidazolecarboxaldehyde (L4), and quinoline-2-carboxaldehyde (L5). The structural characterisation of the ligands L1-L5 (X-ray, ¹H NMR, ¹³C NMR, elemental analysis) and of the coordination polymers {[CuL1]PF₆}_n (herein referred to as Polymer1) and {[AgL1]BF₄}_n, (herein referred to as Polymer2, X-ray, ¹H NMR, ESI-MS) is herein described in detail. The single crystal X-ray structures of complexes Polymer1 and Polymer2 were also investigated, leading to the description of one-dimensional coordination polymers. The spectroscopic and in silico evaluation of the most promising compounds as DNA and RNA binders, as well as the study of the influence of the 1D supramolecular polymers Polymer1 and Polymer2 on the proliferation of Escherichia coli bacteria, were performed in view of their nucleic acid-modulating and antimicrobial applications. Spectroscopic measurements (UV–Vis) combined with molecular docking calculations suggest that the thiazolecarboxaldehyde derivative L1 is able to bind CT-DNA with a mechanism different from intercalation involving the thiazole ring in the molecular recognition and shows a binding affinity with DNA higher than RNA. Finally, Polymer2 was shown to slow down the proliferation of bacteria much more effectively than the free Ag(I) salt.