Tetracyanido(difluorido)phosphates M+[PF2(CN)4]−

The systematic study of the reaction of M[PF₆] salts and Me₃SiCN led to a synthetic method for the synthesis and isolation of a series of salts containing the unprecedented [PF₂(CN)₄]^? ion in good yields. The reaction temperature, pressure, and stoichiometry were optimized. The crystal structures of M[PF₂(CN)₄] (M=[nBu₄N]⁺, Ag⁺, K⁺, Li⁺, H₅O₂⁺) were determined. X‐ray crystallography showed the exclusive formation of the cis isomer in accord with ³¹P and ¹⁹F solution NMR spectroscopy data. Starting with the K[PF₂(CN)₄] the room temperature ionic liquid EMIm[PF₂(CN)₄] was prepared exhibiting a rather low viscosity.     

Synthesis,Structure, and Reactivity of 5‐(Aryl)dibenzothiophenium Triflates

A synthetic protocol for the preparation of 5‐(aryl)dibenzothiophenium salts starting from inexpensive dibenzothiophene S‐oxide and simple arenes is reported. The scope of the method regarding the nature of the arene is evaluated, intermediates along the reaction sequence have been trapped, and side‐reactions identified. In addition, the X‐ray structures of a complete set of these salts are reported and their reactivities studied. Specifically, chemoselective Suzuki coupling is observed at the dibenzothiophenium in the presence of iodides.     

Synthesis,Structure, and Physical Properties of 5,7,14,16‐Tetraphenyl‐8:9,12:13‐bisbenzo‐hexatwistacene

A novel compound, 5,7,14,16‐tetraphenyl‐8:9,12:13‐bisbenzo‐hexatwistacene ( TBH ), has been successfully synthesized through a retro‐Diels–Alder reaction. Single‐crystal structure analysis indicated that TBH has a twisted configuration with a torsion angle of 27.34°. The HOMO–LUMO gap of TBH calculated from the difference between the half‐wave redox potentials (E_1/2^ox=+0.40 eV and E_1/2^red=?1.78 eV) is 2.18 eV, which is in good agreement with the band gap (2.19 eV) derived from the UV/Vis absorption data. In addition, organic light‐emitting devices using TBH as emitter have been fabricated. The results revealed that TBH is a promising red light‐emitting candidate for applications in organic light‐emitting diodes.     

Phase‐ and Size‐Controllable Synthesis of Hexagonal Upconversion Rare‐Earth Fluoride Nanocrystals through an Oleic Acid/Ionic Liquid Two‐Phase System

Herein, we introduce a facile, user‐ and environmentally friendly (n‐octanol‐induced) oleic acid (OA)/ionic liquid (IL) two‐phase system for the phase‐ and size‐controllable synthesis of water‐soluble hexagonal rare earth (RE=La, Gd, and Y) fluoride nanocrystals with uniform morphologies (mainly spheres and elongated particles) and small sizes (<50 nm). The unique role of the IL 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BmimPF₆) and n‐octanol in modulating the phase structure and particle size are discussed in detail. More importantly, the mechanism of the (n‐octanol‐induced) OA/IL two‐phase system, the formation of the RE fluoride nanocrystals, and the distinctive size‐ and morphology‐controlling capacity of the system are presented. BmimPF₆ is versatile in term of crystal‐phase manipulation, size and shape maintenance, and providing water solubility in a one‐step reaction. The luminescent properties of Er³⁺‐, Ho³⁺‐, and Tm³⁺‐doped LaF₃, NaGdF₄, and NaYF₄ nanocrystals were also studied. It is worth noting that the as‐prepared products can be directly dispersed in water due to the hydrophilic property of Bmim⁺ (cationic part of the IL) as a capping agent. This advantageous feature has made the IL‐capped products favorable in facile surface modifications, such as the classic Stober method. Finally, the cytotoxicity evaluation of NaYF₄:Yb,Er nanocrystals before and after silica coating was conducted for further biological applications.     

Facile Synthesis of Well‐Defined Branched Sulfur‐Containing Copolymers: One‐Pot Copolymerization of Carbonyl Sulfide and Epoxide

Topological polymers possess many advantages over linear polymers. However, when it comes to the poly(monothiocarbonate)s, no topological polymers have been reported. Described herein is a facile and efficient approach for synthesizing well‐defined branched poly(monothiocarbonate)s in a “grafting through” manner by copolymerizing carbonyl sulfide (COS) with epichlorohydrin (ECH), where the side‐chain forms in situ. The lengths of the side‐chains are tunable based on reaction temperatures. More importantly, enhancement in thermal properties of the branched copolymer was observed, as the T_g value increased by 22 °C, compared to the linear analogues. When chiral ECH was utilized, semicrystalline branched poly(monothiocarbonate)s were accessible with a T_m value of 112 °C, which is 40 °C higher than that of the corresponding linear poly(monothiocarbonate)s. The strategy presented herein for synthesizing branched polymers provides efficient and concise access to topological polymers.     

Modular Synthesis of Nona‐Decasaccharide Motif from Psidium guajava Polysaccharides: Orthogonal One‐Pot Glycosylation Strategy

The synthesis of long, branched, and complex carbohydrate sequences remains a challenging task in chemical synthesis. Reported here is an efficient and modular one‐pot synthesis of a nona‐decasaccharide and shorter sequences from Psidium guajava polysaccharides, which have the potent α‐glucosidase inhibitory activity. The synthetic strategy features: 1) several one‐pot glycosylation reactions on the basis of N‐phenyltrifluoroacetimidate (PTFAI) and Yu glycosylation to streamline the chemical synthesis of oligosaccharides, 2) the successful and efficient assembly sequences (first O3′, second O5′, final O2′) toward the challenging 2,3,5‐branched Araf motif, 3) the stereoselective 1,2‐cis‐glucosylation by reagent control, and 4) the convergent [6+6+7] one‐pot coupling reaction for the final assembly of the target nona‐decasaccharide. This orthogonal one‐pot glycosylation strategy can streamline the chemical synthesis of long, branched, and complicated carbohydrate chains.     

Application of Static Charge Transfer within an Ionic‐Liquid Force Field and Its Effect on Structure and Dynamics

The effects of linear scaling of the atomic charges of a reference potential on the structure, dynamics, and energetics of the ionic liquid 1,3‐dimethylimidazolium chloride are investigated. Diffusion coefficients that span over four orders of magnitude are observed between the original model and a scaled model in which the ionic charges are ±0.5 e. While the three‐dimensional structure of the liquid is less affected, the partial radial distribution functions change markedly—with the positive result that for ionic charges of ±0.7 e, an excellent agreement is observed with ab initio molecular dynamics data. Cohesive energy densities calculated from these partial‐charge models are also in better agreement with those calculated from the ab initio data. We postulate that ionic‐liquid models in which the ionic charges are assumed to be ±1 e overestimate the intermolecular attractions between ions, which results in overstructuring, slow dynamics, and increased cohesive energy densities. The use of scaled‐charge sets may be of benefit in the simulation of these systems—especially when looking at properties beyond liquid structure—thus providing an alternative to computationally expensive polarisable force fields.     

Application of Fundamental Organometallic Chemistry to the Development of a Gold‐Catalyzed Synthesis of Sulfinate Derivatives

The development of a gold(I)‐catalyzed sulfination of aryl boronic acids is described. This transformation proceeds through an unprecedented mechanism which exploits the reactivity of gold(I)–heteroatom bonds to form sulfinate anions. Further in situ elaboration of the sulfinate intermediates leads to the corresponding sulfones and sulfonamides, two pharmacophores routinely encountered in drug discovery.     

An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts

A series of fluorescent imidazolium‐based salts containing the cation [AnCH₂MeIm]⁺ (in which An=anthracene and Im=the imidazolium cation) with Cl^?, BF₄^?, PF₆^?, SO₃CF₃^?, [N(CN)₂]^?, [N(SO₂CF₃)₂]^?, or PhBF₃^? anions have been prepared and characterized. X‐ray diffraction analysis of four of the salts reveals a number of C? H???X‐type (X=O, N, F) hydrogen bonds between the hydrogen atoms from the imidazolium ring and in some cases from the anthracene ring with the electronegative atoms of the anions. Additionally, C? H???π interactions can be found in all the salts analyzed by X‐ray diffraction, whereas π–π stacking is observed only in the salt containing the phenyltrifluoroborate anion. Fluorescence emission analysis in acetonitrile shows that the fluorescence of these salts varies significantly according to the nature of the anion, and correlates to the extent of ion pairing present in solution. Photodimerization of these salts was observed, and in one case a dimer has been isolated and characterized by X‐ray crystallography.     

A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric Pressure and Room Temperature: Synthesis of Quinazoline‐2,4(1H,3H)‐diones

The chemical fixation of CO₂ under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO₂‐reactive protic ionic liquid (PIL), [HDBU⁺][TFE^?], was designed by neutralization of the superbase 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO₂ and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO₂ with 2‐aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline‐2,4(1H,3H)‐diones in excellent yields.     

Lewis Acid Catalyzed Synthesis of Cyanidophosphates

Salts containing new cyanido(fluorido)phosphate anions of the general formula [PF_6?n(CN)_n]^? (n=1–4) were synthesized by a very mild Lewis‐acid‐catalyzed synthetic protocol and fully characterized. All [PF_6?n(CN)_n]^? (n=1–4) salts could be isolated on a preparative scale. It was also possible to detect the [PF(CN)₅]^? but not the [P(CN)₆]^? anion. The best results with respect to purity, yield, and low cost were obtained when the F^?/CN^? substitution reactions were carried out in ionic liquids.     

Synthesis of cyano-bridged magnetic nanoparticles using room-temperature ionic liquids

A principally new exploit of ionic liquids as an alternative reaction medium in the synthesis of cyano-bridged coordination-polymer nanoparticles is reported. Stable colloid solutions containing nanoparticles of cyano-bridged molecule-based magnets, M)[Fe(CN)6]2/[RMIM][BF4] (M2+=Ni, Cu, Co) and Fe4[Fe(CN)6]3/[RMIM][BF4] (R=1-butyl (BMIM), 1-decyl (DMIM)), were prepared in the corresponding 1-R-3-methylimidazolium tetrafluoroborate [RMIM][BF4], which acts as both a stabilising agent and a solvent. By varying the length of the N-alkyl chain on the imidazolium cation of [RMIM]+ and the temperature, the growing process can be controlled to produce nanoparticles of different sizes. By studying the magnetic properties of frozen colloids it is shown that the relaxation of magnetisation is strongly influenced by interparticle interactions, which leads to the appearance of spin-glass-like dynamics in these systems.     

Caspase抑制剂的结构及合成

Caspase在细胞凋亡中起着关键作用,因此Caspase抑制剂的研究成为当今生命科学领域的重要课题之一。人工合成的Caspase抑制剂主要分为肽类和非肽类。本文着重介绍了常见肽类和非肽类Caspase抑制剂的结构及合成方法,并介绍了相关高活性抑制剂的活性数据。