Axially-chiral boramidine for detailed (chir)optical studies.

The inclusion of boron atoms into chiral π-conjugated systems is an effective strategy to unlock unique chiroptical properties. Herein, the preparation and characterization of a configurationally stable axially-chiral boramidine are reported, showcasing absorption in the UV domain, deep-blue fluorescence ( up to 94%), and |10| and values. Detailed photophysical studies and quantum-chemical calculations clearly elucidate the deactivation pathways of the emissive state to triplet excited states, involving increased spin-orbit coupling between the lowest singlet excited state and an upper triplet state.

Localization and Melting of Interfaces in the Two-Dimensional Quantum Ising Model.

We study the nonequilibrium evolution of coexisting ferromagnetic domains in the two-dimensional quantum Ising model-a setup relevant in several contexts, from quantum nucleation dynamics and false-vacuum decay scenarios to recent experiments with Rydberg-atom arrays. We demonstrate that the quantum-fluctuating interface delimiting a large bubble can be studied as an effective one-dimensional system through a "holographic" mapping. For the considered model, the emergent interface excitations map to an integrable chain of fermionic particles.

Recent improvements to the selectivity of extraction-based optical ion sensors.

Optical sensors continue to demonstrate tremendous potential across a wide range of applications due to their high versatility and low cost. This feature article will focus on a number of recent advances made in improving the performance of extraction-based optical ion sensors within our group. This includes the progress of anchored solvatochromic transduction to provide pH and sample volume independent optical responses in nanoemulsion-based sensors.

Protamine/heparin optical nanosensors based on solvatochromism.

Optical nanosensors for the detection of polyions, including protamine and heparin, have to date relied upon ion-exchange reactions involving an analyte and an optical transducer. Unfortunately, due to the limited selectivity of the available ionophores for polyions, this mechanism has suffered from severe interference in complex sample matrices. To date no optical polyion nanosensors have demonstrated acceptable performance in serum, plasma or blood.

Regiodivergent synthesis of pyrazino-indolines triazocines α-imino carbenes addition to imidazolidines.

Hexahydropyrazinoindoles were prepared in a single step from -sulfonyl triazoles and imidazolidines. Under dirhodium catalysis, α-imino carbenes were generated and formed nitrogen ylide intermediates that, after subsequent aminal opening, afforded the pyrazinoindoles predominantly formal [1,2]-Stevens and tandem Friedel-Crafts cyclizations. Of mechanistic importance, a regiodivergent reactivity was engineered through the use of a specific unsymmetrically substituted imidazolidine that promoted the exclusive formation of 8-membered ring 1,3,6-triazocines.

From reactive carbenes to chiral polyether macrocycles in two steps - synthesis and applications made easy?

Chiral polyether macrocycles are versatile molecules. For their preparation, original two-step procedures were recently developed and present the advantages of high concentration conditions and simple starting reagents (stable diazo reagents, small cyclic ethers, aliphatic or aromatic amines). Enantiopure materials are readily afforded by CSP-HPLC on a semi-preparative scale.

Merging polyacenes and cationic helicenes: from weak to intense chiroptical properties in the far red region.

A series of helical tetracenes and pentacenes was synthesized from cationic [6] and [4]helicene precursors. These colorful acenes fluoresce in the far red region. While [4]helicene-based pentacenes exhibit chiroptical properties mainly in the UV region, [6]helicene-derived tetracenes show enhanced ECD in the visible range, in addition to clear CPL responses.

Ligand Migration from Cluster to Support: A Crucial Factor for Catalysis by Thiolate-protected Gold Clusters.

Thiolate protected metal clusters are valuable precursors for the design of tailored nanosized catalysts. Their performance can be tuned precisely at atomic level, e. g.

Core-Substituted Naphthalenediimides: LUMO Levels Revisited, in Comparison with Preylenediimides with Sulfur Redox Switches in the Core.

Core-substituted naphthalenediimides (NDIs) attract increasing attention to bind, transport, and transform electrons, anions, anionic intermediates, and anionic transition states, and to shine as most colorful rainbow fluorophores. The energy level of their lowest unoccupied molecular orbital (LUMO) is decisive for many of these applications. Here, differential pulse voltammetry (DPV) measurements for a consistent series of NDIs are reported to extract exact LUMO levels under identical conditions.

Design and Synthesis of Mixed Oligomers with Thiophenes, Dithienothiophene S,S-Dioxides, Thieno[3,4]pyrazines and 2,1,3-Benzothiadiazoles: Flipper Screening for Mechanosensitive Systems.

Monomers with large surface area and high quantum yield, that is fluorescent flippers, have been engineered into twisted push-pull oligomers to create membrane probes with high mechanosensitivity and long fluorescence lifetime. Here, the synthesis and characterization of thieno[3,4]pyrazines and 2,1,3-benzothiadiazoles are described in comparison with the original dithienothiophene S,S-dioxides. Dithienothiophene S,S-dioxide flippers are confirmed as the best reported so far, and poor results with single flipper probes support that two flippers are needed for the probe to really "swim", that is, for high mechanosensitivity.

Direct coupling of carbenium ions with indoles and anilines for the synthesis of cationic π-conjugated dyes.

A C-C bond forming reaction occurs spontaneously between tris-(2,6-dimethoxyphenyl)carbenium ions and indoles/anilines. The carbocation acts both as an electrophile and an oxidant. Effective cationic π-conjugated dyes are formed resulting in a strong hyper- and bathochromism.

1,2-Sulfone rearrangement in organocatalytic reactions.

The 1,2-sulfone rearrangement resulting from nucleophilic addition to bis activated vinyl-sulfones has been studied in more detail. Various nucleophiles activated by different types of catalysts (enamine, Brönsted base, thiourea) are able to promote such rearrangement in excellent yields and moderate to excellent enantioselectivities (up to 94% ee). Mechanistic studies have led to a better understanding of the mechanism and allowed its application to other electrophiles such as vinyl-sulfone acrylates.