Photoproduction of Proton Gradients with π-Stacked Fluorophore Scaffolds in Lipid Bilayers

Rigid-rod anion–π slides for multiion hopping across lipid bilayers

Shape-persistent oligo-p-phenylene-N,N-naphthalenediimide (O-NDI) rods are introduced as anion-pi slides for chloride-selective multiion hopping across lipid bilayers. Results from end-group engineering and covalent capture as O-NDI hairpins suggested that self-assembly into transmembrane O-NDI bundles is essential for activity. A halide topology VI (Cl > F > Br approximately I, Cl/Br approximately Cl/I > 7) implied strong anion binding along the anion-pi slides with relatively weak contributions from size exclusion (F >or= OAc). Anomalous mole fraction effects (AMFE) supported the occurrence of multiion hopping along the pi-acidic O-NDI rods. The existence of anion-pi interactions was corroborated by high-level ab initio and DFT calculations. The latter revealed positive NDI quadrupole moments far beyond the hexafluorobenzene standard. Computational studies further suggested that anion binding occurs at the confined, pi-acidic edges of the sticky NDI surface and is influenced by the nature of the phenyl spacer between two NDIs. With regard to methods development, a detailed analysis of the detection of ion selectivity with the HPTS assay including AMFE in vesicles is provided.

Synthetic pores with sticky π-clamps

In this report, we describe design, synthesis, evaluation and molecular dynamics simulations of synthetic multifunctional pores with pi-acidic naphthalenediimide clamps. Experimental evidence is provided for the formation of unstable but inert, heterogeneous and acid-insensitive dynamic tetrameric pores that are sensitive to base and ionic strength. Blockage experiments reveal that the introduction of aromatic electron donor-acceptor interactions provides access to the selective recognition of pi-basic intercalators within the pore. This breakthrough is important for the application of synthetic pores as multianalyte sensors.

Synthetic functional π-stack architecture in lipid bilayers

Neglected until recently, pi-stack architecture is rapidly emerging as a powerful strategy to create function in lipid bilayer membranes. Recent reports describe supramolecular rosettes acting as hosts of intercalating guests, to assemble in bilayer membranes and, in the case of stacked guanosine and folate quartets, to form ion channels. The introduction of rigid-rod pi-stack architecture allowed us to address one of the great challenges in the field, i.e. ligand gating. Inspiring pi-stack chemistry from related fields, covering rainbow coloration, conductivity, as well as the critical dependence of charge mobilities on the precision of supramolecular organization is summarized to zoom in on arguably the most promising application of functional pi-stack architecture in lipid bilayers, that is the creation of multifunctional photosystems.

Dibenzopentarylenebis(dicarboximide)s: Novel near-infrared absorbing dyes

The facile synthesis of the new class of core-extended rylene chromophores, dibenzopentarylenebis(dicarboximide)s, having an intense absorption at 1020-1040 nm, is presented.