Solid-state interconversions of coordination networks and hydrogen-bonded salts

Thermal or chemical treatment of crystalline 4,4-bipyridinium salts of [MCl4]2- (M=Co, Zn, Fe, or Pt) leads to HCl loss and formation of coordination network solids [{MCl2(4,4-bipy)}n]. For M=Co, Zn, and Fe, these solids can also be prepared by mechanochemical means. Their exposure to HCl vapor or the mechanochemical reaction of metal dichlorides with [4,4-H2bipy]Cl2 gives [4,4-H2bipy]2+ salts of [CoCl4]2-, [ZnCl4]2-, and, for the first time, [FeCl4]2-.

Alkene-arene meta photocycloadditions with a four-carbon-atom tether: efficient approach toward the polycyclic ring systems of aphidicolin and stemodinone

At the end of its tether! The fusion of a six-membered ring onto the four-carbon-atom tether of substrate 1 provides an efficient approach toward the polycyclic ring systems of the natural products aphidicolin and stemodinone. The reaction represents a unique example of a preference for product formation from an endo exciplex in an intramolecular system (exo:endo 2:3=1.0:1.2).

Ligand bridging of the DNA Holliday junction: molecular recognition of a stacked-X four-way junction by a small molecule

Planning a Holliday: A new mode of binding to a stacked-X, four-way Holliday junction is described in which a chromophore molecule binds across the center of the junction and two adenine residues are replaced by the acridine chromophores at either side of the crossover. This binding mode is specific for the Holliday junction and does not cause unwinding of the DNA helices.

Recognition of polyimide sequence information by a molecular tweezer

Specific monomer sequences in aromatic copolyimides are recognized through their -stacking and hydrogen-bonding interactions with a sterically and electronically complementary molecular tweezer. These interactions enable the tweezer molecule to read monomer sequences comprising up to 27 aromatic rings by multiple adjacent binding to neighboring sites on the polymer chain.

Peptide fibrillization

An important factor in many diseases based on the deposition of amyloids is the fibrillization of peptides. Furthermore, fibril formation also promises applications in bionanotechnology: fibrillar peptide hydrogels can be made for cell scaffolds and as substrates for functional and responsive biomaterials, biosensors, and nanowires. The mechanisms and kinetics of fibril formation are discussed.

Biological soft materials

The soft side of life: Recent insights into the self-assembly of biological materials, including proteins, DNA, lipids, and blood cells, are reviewed. The particular focus is on applying concepts from soft-matter physics and chemistry to understand structural self-organization.