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Abstract: A series of artificial metal–base tetrads composed of a CuII cation coordinating to four pyridines, covalently attached to the ends of tetramolecular G‐quadruplex DNA strands [LA–Dd(G4)]4 (LA–D=ligand derivatives), was systematically studied. Structurally, the square‐planar [Cu(pyridine)4] complex behaves analogously to the canonical guanine quartet. Copper coordination to all studied ligand derivatives was found to increase G‐quadruplex thermodynamic stability, tolerating a great variety of ligand linker lengths (1–5 atoms) and thus demonstrating the robustness of the chosen ligand design. Only at long linker lengths, the stabilizing effect of copper binding is compensated by the loss of conformational freedom. A previously reported ligand LE with chiral backbone enables incorporation at any oligonucleotide position. We show that ligand chirality distinctly steers CuII‐induced G‐quadruplex stabilization. 5′‐End formation of two metal–base tetrads by tetramolecular G‐quadruplex [LE2d(G)4]4 shows that stabilization in the presence of CuII is not additive. All results are based on UV/Vis thermal denaturation, thermal difference, circular dichroism experiments and molecular dynamics simulations. [ABSTRACT FROM AUTHOR]

The combination of pyridyl ligands and square-planar Pd(II) or Pt(II) cations has proven to be a very reliable recipe for the realization of supramolecular self-assemblies. This tutorial review deals with the design, synthesis and host-guest chemistry of discrete coordination cages built according to this strategy. The focus is set on structures obeying the formula [PdnL2n] (n = 2-4). The most discussed ligands are bent, bis-monodentate bridges having their two donor sites pointing in the same direction. The structures of the resulting cages range from simple globules over intertwined knots to interpenetrated dimers featuring three small pockets instead of one large cavity. The cages have large openings that allow small guest molecules to enter and leave the cavities. Most structures are cationic and thus favour the uptake of anionic guests. Some examples of host-guest complexes are discussed with emphasis on coencapsulation and allosteric binding phenomena. Aside from cages in which the ligands have only a structural role, some examples of functional ligands based on photo- and redox-active backbones are presented. [ABSTRACT FROM AUTHOR]

Review: [54 refs. [ABSTRACT FROM AUTHOR]