Development of a Continuous Photochemical Benzyne-Forming Process

A continuous-flow process is presented that enables the safe generation and derivatization of benzyne under photochemical conditions. This is facilitated by a new high-power LED lamp emitting light at 365 nm. The resulting flow process effectively controls the release of gaseous by-products based on an adjustable backpressure regulator and delivers a series of heterocyclic products in a short residence time of 3 minutes. The robustness of this methodology is demonstrated for the rapid generation of benzotriazoles, 2H-indazoles and various furan-derived adducts, facilitating the preparation of these important heterocyclic scaffolds via a simple and readily scalable flow protocol

Acetonitrile­[2-({bis[2,4,6-tris­(trifluorido­meth­yl)phen­yl]phosphan­yloxy}meth­yl)pyridine]­meth­ylpalladium(II) hexa­fluoro­anti­monate dichloro­methane hemisolvate

In the title compound, [Pd(CH3)(C24H10F18NOP)(CH3CN)][SbF6]·0.5CH2Cl2, the PdII atom has a distorted square-planar environment being coordinated by an acetonitrile N atom [Pd—N = 2.079 (3) Å], a methyl C atom [Pd—C = 2.047 (4) Å] and the bidentate ligand 2-({[2,4,6-tris­(trifluoro­meth­yl)phen­yl]phosphan­yloxy}meth­yl)pyridine (L). In L, the short distance of 3.621 (3) Å between the centroids of pyridine and benzene rings indicates the presence of a π–π inter­action. The crystal packing exhibits weak inter­molecular C—H⋯F contacts. The solvent mol­ecule has been treated as disordered between two positions of equal occupancy related by an inversion center

Synthesis of Tetracyclic 2,3-Dihydro-1,3-diazepines from a Dinitrodibenzothiophene Derivative

Triply fused 1,3-diazepine derivatives have been obtained by acidic reduction of rotationally locked and sterically hindered nitro groups in the presence of an aldehyde or ketone. The nitro groups are sited on adjacent rings of a dicyanodibenzothiophene-5,5-dioxide, which also displays fully reversible two-electron-accepting behavior. The synthesis, crystallographically determined molecular structures, and aspects of the electronic properties of these new molecules are presented

Error estimates for solid-state density-functional theory predictions: an overview by means of the ground-state elemental crystals

Predictions of observable properties by density-functional theory calculations (DFT) are used increasingly often in experimental condensed-matter physics and materials engineering as data. These predictions are used to analyze recent measurements, or to plan future experiments. Increasingly more experimental scientists in these fields therefore face the natural question: what is the expected error for such an ab initio prediction? Information and experience about this question is scattered over two decades of literature. The present review aims to summarize and quantify this implicit knowledge. This leads to a practical protocol that allows any scientist - experimental or theoretical - to determine justifiable error estimates for many basic property predictions, without having to perform additional DFT calculations. A central role is played by a large and diverse test set of crystalline solids, containing all ground-state elemental crystals (except most lanthanides). For several properties of each crystal, the difference between DFT results and experimental values is assessed. We discuss trends in these deviations and review explanations suggested in the literature. A prerequisite for such an error analysis is that different implementations of the same first-principles formalism provide the same predictions. Therefore, the reproducibility of predictions across several mainstream methods and codes is discussed too. A quality factor Delta expresses the spread in predictions from two distinct DFT implementations by a single number. To compare the PAW method to the highly accurate APW+lo approach, a code assessment of VASP and GPAW with respect to WIEN2k yields Delta values of 1.9 and 3.3 meV/atom, respectively. These differences are an order of magnitude smaller than the typical difference with experiment, and therefore predictions by APW+lo and PAW are for practical purposes identical.Comment: 27 pages, 20 figures, supplementary material available (v5 contains updated supplementary material

Direct Amidation of Amino Acid Derivatives Catalyzed by Arylboronic Acids: Applications in Dipeptide Synthesis

The direct amidation of amino acid derivatives catalyzed by arylboronic acids has been examined. The reaction was generally slow relative to simple amine-carboxylic acid combinations though proceeded at 65–68 °C generally avoiding racemization. 3,4,5-Trifluorophenylboronic and o-nitrophenylboronic acids were found to be the best catalysts, though for slower dipeptide formations, high catalyst loadings were required and an interesting synergistic catalytic effect between two arylboronic acids was discovered

Optical and Polarity Control of Donor–Acceptor Conformation and Their Charge-Transfer States in Thermally Activated Delayed-Fluorescence Molecules

This study reports two novel D–A–D molecules, 2,7-bis(phenothiazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DPT-TXO2) and 2,7-bis(1-methylphenothiazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DMePT-TXO2), where the latter differs by only a methyl group incorporated on each of the donor units. DMePT-TXO2 in solution and in solid state shows dual charge-transfer (CT) emission. The CT states come from two distinctive conformations between the D and A units. Experiments show that the emission contribution of each state can be controlled by the polarity of the environment and by the excitation energy. Also, how the different conformers can be used to control the TADF mechanism is analyzed in detail. These results are important as they give a more in-depth understanding about the relation between molecular conformation and the TADF mechanism, thereby facilitating the design of new TADF molecules

Diaqua­bis­(dimethyl sulfoxide-κO)bis(saccharinato-κN)cobalt(II)

The title complex, [Co(C7H4NO3S)2(C2H6OS)2(H2O)2], contains a Co2+ cation in an octa­hedral coordination environment. The metal atom is surrounded by two different neutral ligands, namely dimethyl­sulfoxide (DMSO) and water, each coordinating through the O atom. The anionic saccharinate (sac; 1,1,3-trioxo-2,3-dihydro-1λ6,2-benzothia­zol-2-ide) ligand coordinates through the N atom. Each of the three similar ligand pairs is in a trans configuration with respect to each other. The Co atom lies on a crystallographic center of symmetry and the octa­hedral geometry is not significantly distorted. A short O—H⋯O hydrogen bond is present between a water H atom and the ketone O atom; two longer hydrogen bonds (intra- and inter­molecular) are also present between a water H and a sulfonic O atom, forming a supramolecular assembly through head-to-tail aggregation between adjacent complexes