From attraction to repulsion: anion-π interactions between bromide and fluorinated phenyl groups

Anion-π interactions in crystals of fluorobenzyl ammonium salts depend on the degree of fluorination at the aromatics.     

Concerted halogen and hydrogen bonding in [RuI2(H2dcbpy)(CO)2]···I2···(CH3OH)···I2···[RuI2(H2dcbpy)(CO)2

A new type of concerted halogen bond-hydrogen bond interaction was found in the solid state structure of [RuI(2)(H(2)dcbpy)(CO)(2)]···I(2)···(MeOH)···I(2)···[RuI(2)(H(2)dcbpy)(CO)(2)]. The iodine atoms of the two I(2) molecules interact simultaneously with each other and with the OH group of methanol of crystallization. The interaction was characterized by single crystal X-ray measurements and by computational charge density analysis based on DFT calculations.     

Crystal Engineering Studies of the Complexes of Ethyl Resorcinarene with Aromatic Nitrogen Heterocycles

Five X-ray structures of complexes of ethyl resorcinarene with aromatic nitrogen heterocycles (imidazole, 1,2,4-triazole, pyridine, pyrazine, 2-pyridylmethanol and quinoline) show that ethyl resorcinarene spontaneously forms molecular inclusion complexes with five- and six-membered aromatic nitrogen heterocycles via π ?π and CH ?π interactions. However, with 10-membered quinoline, no molecular inclusion complex is formed. Instead, quinoline manifests crystal lattice inclusion.     

Self-assembly by co-ordination and strong hydrogen bonding. X-ray crystal structures of a dimeric trisodium complex of a new acidic complexing ligand and its dihydrate

Abstract

The new acidic complexing ligand triethanolamine-O,O,O-triacetic acid, 3, is synthesized by reaction of triethanolamine with chloroacetic acid in the presence of sodium tert-butoxide. The resulting Na complex, 4, and its dihydrate, 5, contain two ligand molecules, both with one Na⁺ ion interaction and both co-ordinated to a third, central, Na⁺ ion. In addition the acidic ligands are hydrogen bonded to each other, like carboxylic acids, and in 4, by three crystallographically symmetric hydrogen bonds, while in 5, due to the breakdown of symmetry, two normal and one crystallographically symmetrical hydrogen bond. Inside this extraordinary dimeric assembly (a pseudo-cryptate) are the three sodium ions encapsulated, like in cryptates, with a Na⁺…Na⁺ distance of 3.357(3) Å (4) and 3.325(2) Å (5). Crystal data, 4: a = 12.198(1) Å, c = 40.926(5) Å, V = 5274(3) Å, trigonal, space group = R-3c (no. 157), d _calc = 1.346 g cm^?3, Z = 6, obs. refl. [I > σI] = 396, R = 0.045; 5: a = 25.045(5) Å, b = 11.373(2) Å, c = 14.301(2) Å, β = 122.38(1)°, V = 3440(1) ų, monoclinic, space group = C2/c, d _calc = 1.446 g cm^?3, Z = 4, obs. refl. [I > 2σI] = 1362, R = 0.041.     

A stereodivergent strategy for the preparation of corynantheine and ipecac alkaloids, their epimers, and analogues: efficient total synthesis of (-)-dihydrocorynantheol, (-)-corynantheol, (-)-protoemetinol, (-)-corynantheal, (-)-protoemetine, and related natural and nonnatural compounds

Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indolo[2,3-a]- and benzo[a]quinolizidines. Construction of the core alkaloid skeletons with the correct absolute and relative stereochemistry relies on an enantioselective and diastereodivergent one-pot cascade sequence followed by an additional diastereodivergent reaction step. This allows for enantio- and diastereoselective synthesis of three out of four possible epimers of the quinolizidine alkaloids that begin from common and easily accessible starting materials by using a common synthetic route. Focus has been made on excluding protecting groups and limiting isolation and purification of synthetic intermediates. This methodology is applied in the total synthesis of the natural products (-)-dihydrocorynantheol, (-)-hirsutinol, (-)-corynantheol, (-)-protometinol, (-)-dihydrocorynantheal, (-)-corynantheal, (-)-protoemetine, (-)-(15S)-hydroxydihydrocorynantheol, and an array of their nonnatural epimers. The potential of this strategy is also demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2-a]quinolizidine derivatives. We also report the formal synthesis of (+)-dihydrocorynantheine, (-)-emetine, (-)-cephaeline, (-)-tubulosine, and (-)-deoxytubulosine.     

Single-mode 212 W tapered fiber laser pumped by a low-brightness source

With a tapered double-clad all-glass ytterbium fiber as a gain medium, a maximum output power of over 200 W at 1079 nm and a slope efficiency of over 70% were demonstrated. The tapered double-clad fiber concept allows for using low-brightness diode bars and results in cost-effective and efficient high-power fiber lasers. The adiabatic conical fiber gain waveguide combines improved pump absorption owing to enhanced mode mixing in the pump cladding, low-noise single fundamental mode operation with M(2)< or =1.02, and strong potential for significant power scaling.     

Synthesis of N-Monosubstituted Sulfondiimines by Metal-free Iminations of Sulfilimium Salts

Sulfondiimines are marginalized entities among nitrogen-containing organosulfur compounds, despite offering promising properties for applications in various fields including medicinal and agrochemical. Herein, we present a metal-free and rapid synthetic procedure for the synthesis of N-monosubstituted sulfondiimines that overcomes current limitations in their synthetic accessibility. Particularly, S,S-dialkyl substrates, which are commonly difficult to convert by existing methods, react well with a combination of iodine, 1,8-diazabicyclo[5.4.0]undec-7-en (DBU), and iminoiodinanes (PhINR) in acetonitrile (MeCN) to furnish the corresponding sulfondiimines in yields up to 85 % (25 examples). Valuable “free” NH-N′H-sulfondiimines can then be accessed by N-deprotection under mild reaction conditions. Several experimental observations suggest a mechanistic pathway diverging from the common radical-based iodine/iminoiodinane mechanism. Based on the experimental results in combination with data obtained by ¹H NMR spectroscopy, ESI mass spectrometry, and crystallographic analysis we propose a direct amination from PhINNs and a reaction path via a cationic iodonitrene.     

Correlation of aluminum doping and lithiation temperature with electrochemical performance of LiNi1-xAlxO2 cathode material

Journal of Solid State Electrochemistry - This article presents a process for producing LiNi1-xAlxO2 (0 &lt;  ×  &lt; 0.05) cathode material with...