Self-Assembled Manganese(I)-Based Selenolato-Bridged Tetranuclear Metallorectangles: Host–Guest Interaction, Anticancer, and CO-Releasing Studies

Abstract

Supramolecular one-step self-assembly of dimanganese decacarbonyl, diaryl diselenide, and linear dipyridyl ligands (L = pyrazine (pz), 4,4′-bipyridine (bpy), and trans-1,2-bis­(4-pyridyl)­ethylene (bpe)) has resulted in the formation of selenolato-bridged manganese­(I)-based metallorectangles. The synthesis of tetranuclear Mn­(I)-based metallorectangles [{(CO)3Mn­(μ-SeR)2Mn­(CO)3}2(μ-L)2] (1–6) was facilitated by the oxidative addition of diaryl diselenide to dimanganese decacarbonyl with the simultaneous coordination of linear bidentate pyridyl linker in an orthogonal fashion. Formation of metallorectangles 1–6 was ascertained using IR, UV–vis, NMR spectroscopic techniques, and elemental analyses. The molecular mass of compounds 2, 4, and 6 were determined by ESI-mass spectrometry. Solid-state structural elucidation of 2, 3, and 6 by single-crystal X-ray diffraction methods revealed a rectangular framework wherein selenolato-bridges and pyridyl ligands define the shorter and longer edges, respectively. Also, the guest binding capability of metallorectangles 3 and 5 with different aromatic guests was studied using UV–vis absorption and emission spectrophotometric titration methods that affirmed strong host–guest binding interactions. The formation of the host–guest complex between metallorectangle 3 and pyrene has been explicitly corroborated by the single-crystal X-ray structure of 3•pyrene. Moreover, select metallorectangles 1–4 and 6 were studied to explore their anticancer activity, while CO-releasing ability of metallorectangle 2 was further appraised using equine heart myoglobin assay.

Silver(I) Complexes with Mefenamic Acid and Nitrogen Heterocyclic Ligands: Synthesis, Characterization, and Biological Evaluation

“…Furthermore, many drugs contain N-heterocycles, and some have shown biological activity. − When N-heterocyclic compounds form complexes with metals, they also exhibit a variety of biological activities; nitrogen heterocyclic complexes have shown their ability to bind with DNA/BSA and exhibited anticancer activity. − Among them, the metal complexes formed by pyridine derivatives demonstrate good antitumor activity and multiple forms of antitumor applications. − A small amount of metal complexes produced by pyrazine derivatives also display anticancer activity. − …”

Self-assembly of thiolato-bridged ester-functionalized Re(i)-based tetranuclear spiro-metallacyclophanes

“…In earlier reports from our group, several types of di-, tetra-, and hexanuclear metallacyclophanes of fac-M(CO) 3 -core (M = Mn/Re) with many kinds of bridging and chelating ligands have been explored using a library of mono-, bi-, and tridentate pyridyl linkers. [81][82][83][84][85][86] In order to extend the chemistry of tetradentate ligands with a facial tricarbonyl rhenium core, we intended to exploit the coordination of the pentaerythritol tetra pyridine carboxylate ligand for developing the scope of tetra ester functionalities in host-guest and molecular recognition studies. Spiro-metallacyclophanes are of particular interest owing to their additional structural features and potential for developing supramolecular photoswitches, trapping of halide ions, and exhibiting luminescent properties.…”