In this communication, we introduce transmembrane anion transport with pnictogen-bonding compounds and compare their characteristics with chalcogen-and halogen-bonding analogs. Tellurium-centered chalcogen bonds are at least as active as antimony-centered pnictogen bonds, whereas iodine-centered halogen bonds are three orders of magnitude less active. Irregular, voltage-dependent single-channel currents, high gating charges, efficient dye leakage and small Hill coefficients support the formation of bulky, membrane-disruptive supramolecular amphiphiles by tris(perfluorophenyl)stibanes that bind anions "too strongly." In contrast, the chalcogen-bonding bis(perfluorophenyl)tellanes do not cause leakage and excel as carriers with nanomolar activity, P(Cl/Na) = 10.4 for anion/cation selectivity and P(Cl/NO3) = 4.5 for anion selectivity. Selectivities are lower with pnictogen-bonding carriers because their membrane-disturbing 3D structure affects also weaker binders (P(Cl/Na) = 2.1, P(Cl/NO3) = 2.5). Their 2D structure, directionality, hydrophobicity and support from proximal anion-π interactions are suggested to contribute to the unique power of chalcogen bonds to transport anions across lipid bilayer membranes. The integration of unorthodox interactions into functional systems is of fundamental importance because it promises access to new activities. 1 Synthetic transport systems 2 have emerged as an attractive tool to assess the functional relevance of such interactions. Realized examples include anion-π interactions in many variations, 1 halogen bonds 3,4 and, more recently, also chalcogen bonds. 5,6 In the following, we elaborate on anion transport with pnictogen bonds in direct comparison to chalcogen and halogen bonds. These so-called s-hole interactions 7,8 originate from highly localized areas of highly positive charge density that appear on heavier and p-block elements. Associated with s* orbitals, the s holes appear at the opposite side of the covalent bonds and deepen with increasing electron deficiency of the atom. As a result, there is one s hole available per atom for halogen bonds, 9 two for chalcogen, 10 three for pnictogen 11,12 and four for tetrel bonds (Figure 1). 7,8 Increasing with polarizability, the depth of the s holes

This article describes four fluorescent membrane tension probes that have been designed, synthesized, evaluated, commercialized and applied to current biology challenges in the context of the NCCR Chemical Biology. Their names are Flipper-TR®, ER Flipper-TR®, Lyso Flipper-TR®, and Mito Flipper-TR®. They are available from Spirochrome.

The design, synthesis, and evaluation of multifunctional dithieno[3,2‐b;2′,3′‐d]thiophene (DTT) trimers is described. Twisted push‐push‐pull or donor‐donor‐acceptor (DDA) trimers composed of one DTT acceptor and two DTT donors show strong mechanochromism in lipid bilayer membranes. Red shifts in excitation rather than emission and fluorescence recovery with increasing membrane order are consistent with planarization of the twisted, extra‐long mechanophores in the ground state. The complementary pull‐pull‐pull or AAA trimers with deep σ holes all along the scaffold are not mechanochromic in membranes but excel with submicromolar anion transport activity. Anion transport along membrane‐spanning strings of chalcogen‐bond donors is unprecedented and completes previous results on transmembrane cascades that operate with equally unorthodox interactions such as halogen bonds and anion‐π interactions.