Error Bounds: Necessary and Sufficient Conditions

The paper presents a general classification scheme of necessary and sufficient criteria for the error bound property incorporating the existing conditions. Several derivative-like objects both from the primal as well as from the dual space are used to characterize the error bound property of extended-real-valued functions on a Banach space.     

A Versatile Approach Towards Nucleobase‐Modified Aptamers

A novel and versatile method has been developed for modular expansion of the chemical space of nucleic acid libraries, thus enabling the generation of nucleobase‐modified aptamers with unprecedented recognition properties. Reintroduction of the modification after enzymatic replication gives broad access to many chemical modifications. This wide applicability, which is not limited to a single modification, will rapidly advance the application of in vitro selection approaches beyond what is currently feasible and enable the generation of aptamers to many targets that have so far not been addressable.     

Reverse Engineering of Conjugated Microporous Polymers: Defect Structures of Tetrakis(4‐ethynylphenyl)stannane Networks

Two different conjugated microporous polymers (CMPs) based on tetrakis(4‐ethynylphenyl)stannane as the repeating unit were synthesized and their BET surfaces and thermal properties were investigated. The first direct method to elucidate the molecular structure of the organic linkers between the tin centers by digestion of the CMP is described. Selective cleavage of the tin–carbon bonds with chloroacetic acid afforded the isolated bridging units and provided insight into the surprisingly varied chemical composition of these networks.     

Redox and Coordination Behavior of the Hexaphosphabenzene Ligand in [(Cp*Mo)2(μ,η6:η6‐P6)] Towards the “Naked” Cations Cu+, Ag+, and Tl+

Although the cyclo‐P₆ complex [(Cp*Mo)₂(μ,η⁶:η⁶‐P₆)] ( 1 ) was reported 30 years ago, little is known about its chemistry. Herein, we report a high‐yielding synthesis of 1 , the complex 2 , which contains an unprecedented cyclo‐P₁₀ ligand, and the reactivity of 1 towards the “naked” cations Cu⁺, Ag⁺, and Tl⁺. Besides the formation of the single oxidation products 3 a,b which have a bisallylic distorted cyclo‐P₆ middle deck, the [M( 1 )₂]⁺ complexes are described which show distorted square‐planar (M=Cu( 4 a ), Ag( 4 b )) or distorted tetrahedral coordinated (M=Cu( 5 )) M⁺ cations. The choice of solvent enabled control over the reaction outcome for Cu⁺, as proved by powder XRD and supported by DFT calculations. The reaction with Tl⁺ affords a layered two‐dimensional coordination network in the solid state.     

Naphthalenebisimides as photofunctional surfactants for SWCNTs – towards water-soluble electron donor–acceptor hybrids

A water soluble naphthalenebisimide derivative (NBI) was synthesized and probed to individualize, suspend, and stabilize single wall carbon nanotubes (SWCNTs). Besides a comprehensive photophysical and electrochemical characterization of NBI, stable suspensions of SWCNTs were realized in buffered D₂O. Overall, the dispersion efficiency of the NBI surfactant was determined by comparison with naphthalene based references. Successful individualization of SWCNTs was corroborated in several microscopic assays. In addition, emission spectroscopy points to the strong quenching of SWCNT centered band gap emission, when NBIs are immobilized onto SWCNTs. The origin of the quenching was found to be strong electronic communication, which leads to charge separation between NBIs and photoexcited SWCNTs, and, which yields reduced NBIs as well oxidized SWCNTs. Notably, electrochemical considerations revealed that the energy content of these charge separated states is one of the highest reported for SWCNT based electron donor–acceptor hybrids so far.     

Syntheses,Crystal Structures,and Properties of the Isotypic Pair [Cr(H2O)6]2[B12H12]3·15H2O and [In(H2O)6]2[B12H12]3·15H2O

Single crystals of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O and [In(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O were obtained by reactions of aqueous solutions of the acid (H₃O)₂[B₁₂H₁₂] with chromium(III) hydroxide and indium metal shot, respectively. The title compounds crystallize isotypically in the trigonal system with space group R$\bar{3}$ c (a = 1157.62(3), c = 6730.48(9) pm for the chromium, a = 1171.71(3), c = 6740.04(9) pm for the indium compound, Z = 6). The arrangement of the quasi‐icosahedral [B₁₂H₁₂]^2– dianions can be considered as stacking of two times nine layers with the sequence …ABCCABBCA… and the metal trications arrange in a cubic closest packed …abc… stacking sequence. The metal trications are octahedrally coordinated by six water molecules of hydration, while another fifteen H₂O molecules fill up the structures as zeolitic crystal water or second‐sphere hydrating species. Between these free and the metal‐bonded water molecules, bridging hydrogen bonds are found. Furthermore, there is also evidence of hydrogen bonding between the anionic [B₁₂H₁₂]^2– clusters and the free zeolitic water molecules according to B–H^δ– ··· ^δ+H–O interactions. Vibrational spectroscopy studies prove the presence of these hydrogen bonds and also show slight distortions of the dodecahydro‐closo‐dodecaborate anions from their ideal icosahedral symmetry (I_h). Thermal decomposition studies for the example of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O gave no hints for just a simple multi‐stepwise dehydration process.     

Structural and Functional Implications of the Interaction between Macrolide Antibiotics and Bile Acids

Macrolide antibiotics, such as azithromycin and erythromycin, are in widespread use for the treatment of bacterial infections. Macrolides are taken up and excreted mainly by bile. Additionally, they have been implicated in biliary system diseases and to modify the excretion of other drugs through bile. Despite mounting evidence for the interplay between macrolide antibiotics and bile acids, the molecular details of this interaction remain unknown. Herein, we show by NMR measurements that macrolides directly bind to bile acid micelles. The topology of this interaction has been determined by solvent paramagnetic relaxation enhancements (solvent PREs). The macrolides were found to be bound close to the surface of the micelle. Increasing hydrophobicity of both the macrolide and the bile acid strengthen this interaction. Both bile acid and macrolide molecules show similar solvent PREs across their whole structures, indicating that there are no preferred orientations of them in the bile micelle aggregates. The binding to bile aggregates does not impede macrolide antibiotics from targeting bacteria. In fact, the toxicity of azithromycin towards enterotoxic E. coli (ETEC) is even slightly increased in the presence of bile, as was shown by effective concentration (EC₅₀) values.     

Metal‐Chelating N,N′‐Bis(4‐dimethylaminophenyl)acetamidinyl Radical: A New Chromophore for the Near‐Infrared Region

A new non‐innocent ligand redox system, N,N′‐bis(4‐dimethylaminophenyl) substituted acetamidinato/acetamidinyl, has been designed and described by example of structurally and spectroscopically characterized ruthenium complexes. The hitherto unreported ligand is responsible for rather intense and narrow absorptions in the near‐infrared region of the one‐ and two‐electron oxidized forms. The spectroscopic, computational, and first structural characterization of an amidinyl radical complex adds to the list of established N‐based radical ligands.