Suzuki-Miyaura cross-coupling reactions are difficult when both reaction partners (boronic acid and halide) are electron-poor. We describe here a system of solvent, catalyst, and ligand with which also electron-poor substrates react, without the necessity to try several conditions. The system consists of N-methylpyrrolidone as solvent, tris(dibenzylidenaceton)dipalladium(0) as catalyst, CuI as cocatalyst, and Davephos as ligand. This combination yields little or no Ullmann product, and the desired cross-coupling product is in moderate to excellent yields.

Hybrid organic-inorganic molecules have recently received great interest due to their unique properties, which give access to their implementation in biological and material sciences. Herein, a new synthetic approach for the direct-linkage of the purely inorganic dodecaborate cluster to organic building blocks through B-C bond is established, using boronic acids as functional groups on the organic moiety, reacting under Suzuki-Miyaura coupling conditions with iodo-undecahydridododecaborate. The choices of ligand (DavePhos) and solvent (N-methylpyrrolidone for electron-poor, CD3 CN for electron-rich groups) are essential for the successful coupling. Ultimately, the newly described methodology is found to be functional-group tolerant covering a wide spectrum of substrates including electron-poor arenes.

A gradient mixer for preparative column chromatography has been developed, using a microcontroller, a three-way solenoid valve, and a one-channel pump of any chosen design, controlled by a microcontroller and with specifications for the gradient entered through a touchscreen. The gradient mixer is economical and can be produced with the design files provided.

Cross-coupling reactions with [B12H11I]2− as one partner have been used successfully for Kumada and Buchwald Hartwig couplings with Pd catalysis. Here, we found that the iodide could be substituted easily, and unexpectedly, with other halides such as Br and Cl, and with pseudohalides such as cyanide, azide, and isocyanate. We found that for Cl, Br, N3, and NCO, tetrabutylammonium salts—or sodium salts—were successful halide sources, whereas for cyanide, CuCN was the only halide source that allowed a successful exchange. The azide could be reacted further in a click reaction with triazoles. While no substitution with fluoride occurred, tetrabutylammonium fluoride in the presence of water led to [B12H11OH]2−. Yields were high to very high, and reaction times were short when using a microwave oven as a heating source.

The toolbox is full of boronic acids for Suzuki–Miyaura coupling. To connect them to the dodecaborate cluster, special tools are necessary: iodine as leaving group on the dodecaborate, DavePhos as special ligand, and solvents that differ for electron-rich and electron-poor boronic acids. With these tools, the coupling can be carried out successfully. More information can be found in the Research Article by D. Gabel and co-workers (DOI: 10.1002/chem.202302466).

A general procedure for connecting dodecaborate clusters to organic building blocks has been found, using boronic acids as functional groups on the organic moiety, reacting under Suzuki-Miyaura coupling conditions with iodo-undecahydridododecaborate. The choices of ligand (DavePhos) and solvent (N-methylpyrrolidone for electron-poor, CD3CN for electron-rich groups) are essential for the success of the coupling. The procedure is not sensitive to the presence of other functional groups which are unable to participate in Suzuki-Miyaura reactions.

A new set of hybrid guest molecules bearing organic and inorganic residues have been studied for their recognition by cyclodextrins in aqueous solution. The guest molecules consist of nitroanilines linked through their amino group to the dodecahydrido-closo-dodecaborate cluster B12H122-, which serves as an anchor group. They show sizable affinity to cyclodextrins, and unexpected photophysical properties, with a very strong and low-energy charge-transfer band. The dodecaborate cluster increases the pKa of the anilines by 5.0 to 5.7 pH units, and the deprotonated forms of the o- and p-nitroaniline derivatives show strong charge transfer absorption bands in the visible part of the spectrum.

Two new approaches to the functionalization of the 1-carba-closo-decaborate anion [1-CB9H10]- at boron atoms via the ring-opening of its 1,4-dioxane derivative with various nucleophiles and Pd-catalysed cross-coupling of its iodo derivative with aromatic amines and heteroaromatics were developed.

Perhalogenated boron clusters derived from B12Br122-, a superchaotropic dianion with a globular icosahedral shape, serve as inorganic cavity binders for cyclodextrins (CDs), in particular for large CDs (γ-CD and δ-CD), with high binding affinity (Ka > 106 M-1) in aqueous solution. This opens the door for applications of this anchoring moiety by linking it to organic residues, prominently fluorescent dyes. We report here the synthesis of a novel fluorescein-substituted perbrominated dodecaborate cluster by a copper(I)-catalyzed azide-alkyne click reaction. The formation of host-guest inclusion complexes between the dodecaborate-modified fluorescein dye and CDs can be readily followed by optical titrations, which afforded a binding constant of ∼1 × 104 M-1 with γ-CD; that is, the cluster functionalization allows binding of an otherwise nonbinding dye to the macrocycle ("anchor dye"). The formation of the 1:1 host-guest inclusion complex between the dye and γ-CD occurs over a broad range of pH values, which allows its application as a sensitive reporter pair according to the indicator displacement method, e.g., for drug detection. In addition, the substituted dye shows outer-wall binding to cucurbiturils through the dodecaborate moiety, leading to the formation of aggregates and significant fluorescence quenching of the dye.

Objectives To develop a new dye formulation for vitreoretinal surgery, which shows increased transparency for better intraoperative handling with better parameters important for use.Methods and analysis A new blue dye, DDG, was synthesised and tested for toxicity and staining. Diglycerol as new density-increasing additive was identified, and its toxicity and lack of influence of the staining with trypan blue (TB) on a collagen membrane as model for the epiretinal membrane was determined. Transparency of the dye solution was evaluated.Results DDG is as alternative to Brilliant Blue G (BBG), with good staining properties for interna limitans models, and a good safety profile. Diglycerol is a new non-toxic additive replacing PEG3350, with reduced viscosity and no reduction in staining, allowing the reduction of TB to achieve the same staining level of the collagen membrane by 40%, with greater transparency of the dye solution and reduced viscosity. Both factors should facilitate a safe removal during surgery.Conclusion A new dye preparation with improved performance in comparison to marketed combinations of BBG and TB was developed. Its reduced TB concentration and viscosity with maintained density allow better tolerance and handling.

Substituted undecahydrido-closo-dodecaborates [B12H11NR2]2- have potential use in materials and drugs, but have presented a synthetic challenge. Microwave-assisted palladium-catalyzed amination of iodo-dodecaborate [B12H11I]2- allows mild and reproducible formation of B-N bonds with aromatic amines, HN-containing heteroaromatics, and amides. The reaction allows general access to amides, reproducible reactions to dodecaborate-substituted anilines, and, for the first time, the substitution of dodecaborate with HN-containing heterocycles.

Convenient methods have been developed to synthesize cyclic oxonium derivatives with tetrahydrofurane, tetrahydropyrane, and 1,4-dioxane, as well as pure mono-halo derivatives (halo = chloro, bromo, iodo) of dodecahydrido-closo-dodecaborate(2-). (c) 2021 Elsevier B.V. All rights reserved.

Purpose: To investigate whether new dyes and dye combinations can give equivalent or better staining in anterior capsule surgery than existing dyes with a low degree of toxicity on relevant cells. Setting: University laboratory of Jacobs University Bremen, Germany. Design: Laboratory experimental study. Methods: Pig eyes were collected post mortem. Cataract was induced by microwave irradiation. Access to the lens capsule was through open-sky surgery. Staining was performed and results were documented by photography. The toxicity of the dyes was evaluated in 3 different cell lines immediately after exposure and with a delay of 24 hours, with exposure in the dark or subsequent strong illumination. Results: A new cyanine dye, BIP (2-[5-[3,3-dimethyl-1-(4-sulfobutyl)-1,3-dihydro-indol-2-ylidene]-penta-1,3-dienyl]-3,3-dimethyl-1-(4-sulfobutyl)-3H-indolium sodium), was found to lead to green staining, with reduced toxicity on corneal endothelial cells. Staining could be further enhanced by combining it with trypan blue. Methylene blue was very toxic, whereas its combination with trypan blue was much less toxic. Conclusions: With BIP alone or in combination with trypan blue, safe staining of the capsule can be achieved, resulting in a green color. (C) 2018 ASCRS and ESCRS

We report the modification of the 2-ammonio group at halogenated decaborate ions with 2,3-epoxypropane, the product of which reacts readily with nucleophiles to form previously inaccessible coupling of polyhedra with organic molecules and materials. We demonstrate that these ions present a good binding motif in supramolecular chemistry.

Metallacarboranes are a class of inorganic boron clusters that have recently been recognized as biologically active compounds. Herein, we report on the host-guest complexation of several cobalt bis(1,2-dicarbollide) anions (COSANs) with cyclodextrins (CDs) in aqueous solution. The binding affinities reach micromolar values, which are among the highest known values for native CDs, and exceed those for neutral hydrophobic organic guest molecules. The entrapment of the COSANs inside the cavity of CDs was confirmed using NMR and UV-visible spectroscopy, mass spectrometry, cyclic voltammetry, and isothermal titration calorimetry. Complexation by CDs greatly influences the photophysical and electrochemical properties of COSANs. In combination with indicator displacement assays, a label-free fluorescence-based method was developed to allow real-time monitoring of the translocation of COSANs through lipid bilayer membranes.

In aqueous solution, host-guest complexation is frequently driven by the hydrophobic effect, which also constitutes a popular approach in the design of supramolecular assemblies. Herein, we report an orthogonal assembly motif, the chaotropic effect, which exploits the tendency of chaotropic anions to associate with hydrophobic surfaces.

Polyhedral carboxymethyl carborane (C2B10H12) derivatives, including mono- and disubstituted o-, m-, and p-isomers, have been synthesized. Supramolecular host-guest complexation of these derivatives with cyclodextrins (CDs; namely, alpha-, beta-, and gamma-CD) has been investigated in water. The globular structure of the carborane binding moiety and its hydrophobic character qualify it as an ideal recognition site to form stable inclusion complexes with macrocyclic host molecules in aqueous solution. The measured binding affinities for the carborane derivatives were in the millimolar range (K-a=10(3)-10(4)m(-1)) with differently sized CDs, and preferential binding to beta-CD.

The hydrophobic and chaotropic effects can be used as orthogonal assembly motifs in water. Cucurbit[7]uril, a water-soluble macrocyclic host, and a ditopic guest molecule, carrying an organic-hydrophobic (adamantane) and an inorganic-chaotropic (dodecahydro-closo-dodecaborate dianion) binding site, have been used to construct hybrid supramolecular architectures. The hydrophobic effect drives the adamantane moiety into the host cavity, while the chaotropic effect allows the association of the dodecaborate cluster onto the host exterior surface. This new strategy facilitates potential applications in surface modification, separation, and purification.