四氟乙烯齐聚体的反应 四氟乙烯四、五聚体和芳香胺的反应

前已报道四氟乙烯四聚体(全氟-3,4-甲基己烯-3)(1)、五聚体(全氟-3,4-二甲基-4-乙基己烯-2)(2)和脂肪烷氧以及脂肪胺的亲核反应.本文报道化合物1,2和芳香胺如苯胺、β-萘胺的反应.由于烯烃1、2双键处于分子中间,因而当亲核试剂进攻时,双键容易发生重排,生成的末端基烯烃更具反应性,故导致一取代、二取代、三取代以及环化降解等复杂产物.     

Boron/nitrogen substitution of the central carbon atoms of the biphenalenyl diradical π dimer: a novel 2e-12c bond and large NLO responses

On the basis of the famous staggered biphenalenyl diradical π dimer 1, the eclipsed biphenalenyl (1a), with no centrosymmetry, was obtained by rotating a layer of 1 by 60° around its central axis. Furthermore, the central carbon atoms of 1 and 1a were substituted by boron and nitrogen atoms to form 2 and 2a with a novel 2e-12c bond. We found that the novel 2e-12c bond is formed by the electron pair of the occupied orbital of the phenalenyl monomer substituted by the nitrogen atom and the unoccupied orbital of the phenalenyl monomer substituted by the boron atom. As a result of the novel 2e-12c bond, 2 and 2a exhibit a fascinating interlayer charge-transfer transition character, which results in a significant difference in the dipole moments (Δμ) between the ground state and the crucial excited state. The values of Δμ for 2 and 2a are 6.4315 and 6.9253 Debye, clearly larger than the values of 0 and 0.0015 Debye for 1 and 1a. Significantly, the boron/nitrogen substitution effect can greatly enhance the first hyperpolarizabilities (β(0) ) of 2 and 2a with a novel 2e-12c bond compared with 1 and 1a with a traditional 2e-12c bond: 0 and 19 a.u. for 1 and 1a are much lower than 3516 and 12272 a.u. for 2 and 2a. Furthermore, the interaction energies (E(int) )of 2 and 2a are larger than those of 1 and 1a, which could be considered as a signature of reliability for the newly designed dimers. Our present work will be beneficial for further theoretical and experimental studies on the properties of molecules with the novel 2e-12c bond.     

Crystal engineering of photochromic diarylethene single crystals

Photochromic performance of diarylethene single crystals was controlled by crystal engineering using non-covalent aromatic-aromatic interactions as the directional intermolecular force. A diarylethene derivative with two pentafluorophenyl groups, 1,2-bis(2-methyl-5-pentafluorophenyl-3-thienyl)perfluorocyclopentene (1a), formed stoichiometric co-crystals with benzene (Bz) and naphthalene (Np) by aryl-perfluoroaryl interactions. Face-to-face pi-stacking interactions between the pentafluorophenyl groups of 1a and the aromatic molecules are responsible for 2:1 and 1:1 stoichiometric compositions in 1a/Bz and 1a/Np co-crystals, respectively. The diarylethene underwent thermally stable and photoreversible photochromic reactions in a homo-crystal of 1a and co-crystals 1a/Bz and 1a/Np. The absorption spectra of the photogenerated closed-ring isomers varied depending on the conformation of the diarylethene molecules packed in the crystals. The diarylethene 1a also formed 1:1 stoichiometric co-crystals with different kinds of diarylethenes, 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene (2a) and 1,2-bis[2-methyl-5-(1-naphthyl)-3-thienyl]perfluorocyclopentene (3a). Both co-crystals 1a/2a and 1a/3a showed photochromism. Although 1a, 2a, and 3a underwent efficient photocyclization reactions in their homo-crystals, highly selective photocyclization reactions of 2a or 3a were observed in the co-crystals. The selective reactions were confirmed by HPLC and X-ray crystallography. Excited energy transfers from 1a to 2a and from 1a to 3a are considered to occur and cause the selective reactions.     

Reactions of Ruthenium–Allenylidene Complexes Tethering a Cyclopropyl Group

Two cyclopropyl allenylidene complexes [Ru]=CCC(R)(C₃H₅) ([Ru]=[RuCp(PPh₃)₂], Cp=Cyclopentadienyl; R=thiophene ( 2a ) and R=Ph ( 2b )) are prepared from the reactions of [Ru]Cl with the corresponding 1‐cyclopropyl‐2‐propyn‐1‐ol in the presence of KPF₆. Thermal treatment, halide‐anion addition, and palladium‐catalyzed reactions of 2a and 2b all lead to a ring expansion of the cyclopropyl group, giving the vinylidene complexes 4a and 4b , respectively, each with a five‐membered ring. This ring expansion proceeds by C C bond formation between Cβ of the cumulative double bond and a methylene group of the cyclopropyl ring. In the reaction of 2a with pyrrole, consecutive formation of two C C bonds, one between C‐2 of pyrrole and Cγ of 2a and the other between C‐3 of pyrrole and Cα, results in the formation of 6a . The reaction proceeds by addition of pyrrole and 1,3‐proton shifts. The hydrogenation of 2a by NaBH₄ is carried out in different solvents. The cumulative double bonds are reduced regioselectively to give a mixture of 7a and 8a . Interestingly, use of different solvents leads to different ratios of 7a and 8a . Presence of a protic solvent like methanol in dichloromethane or chloroform solution increases the yield of 8a , thus revealing that both the rates of hydroboration and deboronation increase. The structures of two new complexes 4a and 6a have been firmly established by X‐ray diffraction analysis.     

Photochromic reactions of diarylethenes in single crystals with intermolecular O--H...N hydrogen-bonding networks

The crystal structures and photochromic performance of a single crystal of a diarylethene derivative possessing carboxyl groups, 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (1 a), and cocrystals of 1 a with 4,4'-, 2,4'-, and 2,2'-bipyridines were examined. In crystal 1 a, a discrete cyclic structure was observed, in which four 1 a molecules are linked through hydrogen bonds between the carboxyl groups. In the homocrystal, photoreactive and photoinactive conformers of 1 a exist in the ratio of 1:1. In the cocrystals of 1 a with bipyridines, O--HN-type hydrogen bonds between 1 a and pyridyl groups were formed, and all 1 a molecules are fixed in a photoreactive conformation. Both the homocrystal 1 a and the cocrystals showed photochromic performances, and color variation from bluish-violet to cyan was observed, depending on the conformation of the packed diarylethene molecules.     

Trichalcogenasumanene ortho‐Quinones: Synthesis,Properties, and Transformation into Various Heteropolycycles

The regioselective transformation of heterobuckybowl trichalcogenasumanenes 1 a , b at peripheral butoxy groups afforded trichalcogenasumanene ortho ‐quinones 2 a , b . Compounds 2 a , b are distinct from 1 a , b in terms of their molecular geometry and electronic state; that is, they have a shallower bowl depth and show absorbance in the NIR region. The reaction of 2 a , b with diamines resulted in a variety of heteropolycycles, including molecular spoon 3 a – 6 a , planar π‐systems 3 b – 6 b , and highly twisted [7‐6‐6]‐fused systems 7 a , b . These new heteropolycycles had different optical/electrical properties: 4 a,b showed hole mobility of approximately 0.002 cm² V⁻¹ s⁻¹, 6 a displayed red emission in both solution and the solid state, and 7 a , b formed tight stacks of the curved π‐surface.     

A Rapid and Efficient Way to Dynamic Creation of Cross‐Reactive Sensor Arrays Based on Ionic Liquids

Based on the simple counterion exchange of ionic liquids, a rapid, facile, and efficient strategy to create a cross‐reactive sensor array with a dynamic tunable feature was developed, and exemplified by the construction of a sensor array for the identification and classification of nitroaromatics and explosives mimics. To achieve a good sensing system with fast response, good sensitivity, and low detection limit, the synthesized ionic liquid receptors were tethered onto a silica matrix with a macro‐mesoporous hierarchical structure. Through the facile anion exchange approach, abundant ionic‐liquid‐based individual receptors with diversiform properties, such as different micro‐environments, diverse molecular interactions, and distinctive physico‐chemical properties, were easily and quickly synthesized to generate a distinct fingerprint of explosives for pattern recognition. The reversible anion exchange ability further endowed the sensor array with a dynamic tunable feature as well as good controllability and practicality for real‐world application. With the assistance of statistical analysis, such as principal component analysis (PCA) and linear discrimination analysis (LDA), an optimized‐size array with a good resolution was rationally established from a large number of IL‐based receptors. The performed experiments suggested that the ionic‐liquid‐based sensing protocol is a general and powerful strategy for creating a cross‐reactive sensor array that could find a wide range of applications for sensing various analytes or complex mixtures.     

A Shared Prebiotic Formation of Neopterins and Guanine Nucleosides from Pyrimidine Bases

The prebiotic origins of biopolymers and metabolic co-factors are key questions in Origins of Life studies. In a simple warm-little-pond model, using a drying phase to produce a urea-enriched solution, we present a prebiotic synthetic path for the simultaneous formation of neopterins and tetrahydroneopterins, along with purine nucleosides. We show that, in the presence of ribose and in a formylating environment consisting of urea, ammonium formate, and water (UAFW), the formation of neopterins from pyrimidine precursors is robust, while the simultaneous formation of guanosine requires a significantly higher ribose concentration. Furthermore, these reactions provide a tetrahydropterin–pterin redox pair. This model suggests a prebiotic link in the origin of purine nucleosides and pterin cofactors that provides a possible deep prebiotic temporal connection for the emergence of nucleic acids and metabolic cofactors.     

Electrokinetic flow in an elliptic microchannel covered by ion-penetrable membrane

The electrokinetic flow of an electrolyte solution in an elliptical microchannel covered by an ion-penetrable, charged membrane layer is examined theoretically. The present analysis extends previous results in that a two-dimensional problem is considered, and the system under consideration simulates the flow of a fluid, for example, in a microchannel of biological nature such as vein. The electroosmostic volumetric flow rate, the total electric current, the streaming potential, and the electroviscous effect of the system under consideration are evaluated. We show that, for a constant hydraulic diameter, the variations of these quantities as a function of the aspect ratio of a microchannel may have a local minimum or a local maximum at a medium level of ionic strength, which depends on the thickness of the membrane layer. For a constant cross-sectional area, the electroosmostic volumetric flow rate, the total electric current, and the streaming potential increase monotonically with the increase in the aspect ratio, but the reverse is true for the electroviscous effect.     

Trichalcogenasumanene ortho‐Quinones: Synthesis,Properties, and Transformation into Various Heteropolycycles

The regioselective transformation of heterobuckybowl trichalcogenasumanenes 1 a , b at peripheral butoxy groups afforded trichalcogenasumanene ortho ‐quinones 2 a , b . Compounds 2 a , b are distinct from 1 a , b in terms of their molecular geometry and electronic state; that is, they have a shallower bowl depth and show absorbance in the NIR region. The reaction of 2 a , b with diamines resulted in a variety of heteropolycycles, including molecular spoon 3 a – 6 a , planar π‐systems 3 b – 6 b , and highly twisted [7‐6‐6]‐fused systems 7 a , b . These new heteropolycycles had different optical/electrical properties: 4 a,b showed hole mobility of approximately 0.002 cm² V⁻¹ s⁻¹, 6 a displayed red emission in both solution and the solid state, and 7 a , b formed tight stacks of the curved π‐surface.     

Controlled Dynamic Helicity of a Folded Macrocycle Based on a Bisterephthalamide with a Twofold Z‐Shaped Structure

Dynamic helicity in a folded macrocycle and control of the helical preference are described. We designed macrocycle 1 with a dual mode of folding through the integration of two flexible units that are arranged twice to form a cyclic structure. As a folding unit, we used a terephthalamide skeleton and a Z‐shaped hydrocarbon: the former acted as a control unit to induce a preference of a particular sense of dynamic helicity and the latter was just a spacer. A terephthalamide unit provided a binding site for capturing a ditopic hydrogen‐bonding guest when it adopted helically folded syn forms (M/P). Thus, only the terephthalamide unit controlled the helical sense of dynamic helicity in a folded macrocycle through the supramolecular transmission of chirality upon complexation with a chiral ditopic guest. In addition, chirality on a host could also contribute to the control of the helical preference in a folded macrocycle, which led to exceptionally enhanced chiroptical signals.     

Equilibrium between a vinylogous ylide and a phosphonium dienolate zwitterion: vinylogous Wittig olefination versus vinylogous aldol-type reaction

This paper describes the equilibrium established between a phosphonium dienolate zwitterion and a vinylogous phosphorus ylide, and their reactions with aldehydes. The reactions between ethyl 2-methyl-2,3-butadienoate and various aldehydes occur through either a phosphonium dienolate or a vinylogous ylide intermediate, depending on the presence/absence of a Lewis acid and the nature of the phosphine. We observed a rare vinylogous Wittig olefination from the reaction between ethyl 2-methyl-2,3-butadienoate and an electron-deficient aromatic aldehyde in the presence of a stoichiometric amount of an electron-deficient triarylphosphine and a catalytic amount of a Lewis acid (e.g., BF₃·Et₂O). On the other hand, the use of triphenylphosphine, in the absence of a Lewis acid, facilitated vinylogous aldol addition, accompanied by a rare 1,2-aryl phosphorus-to-carbon migration.     

Triarylborane-Appended Anils and Boranils: Solid-State Emission,Mechanofluorochromism, and Phosphorescence

Herein, the design, synthesis, optical properties, and mechanofluorochromism characteristics of a series of conjugates having covalently linked triarylborane (TAB) and anil/boranil units (TAB-anil: 1 a – 3 a and TAB-boranil: 1 – 3 ) are reported. The electronic interactions between TAB and anil/boranil in 1 a – 3 a and 1 – 3 were fine-tuned by changing the boryl moiety's position on the phenyl spacer connecting the BMes₂ (Mes=mesityl) and anil/boranil units. A boryl moiety at the meta position ( 1 a ) of the phenyl spacer stabilizes the enolic form (E-OH), whereas a boryl moiety at the para position ( 2 a and 3 a ) stabilizes the keto form (Z-NH) in the solid state. However, in solution 1 a , 2 a , and 3 a exhibit keto–enol tautomerism in both ground and excited states. Compounds 1 a – 3 a and 1 – 3 show red-shifted absorption compared with 4 a and 4 , which are devoid of TAB moieties, which indicate effective participation of an empty p orbital on the boron center in 1 a – 3 a and 1 – 3 . Compounds 1 and 2 showed fluorescence variations in response to external stimuli such as mechanical grinding. Long phosphorescence lifetimes of 18–46 ms were observed for compounds 1 – 3 . The observed optical properties of 1 a – 3 a and 1 – 3 are rationalized in the context of quantum mechanical calculations.     

Differentiation of proanthocyanidin tannins from seeds, skins and stems of grapes (Vitis vinifera) and heartwood of Quebracho (Schinopsis balansae) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thioacidolysis/liquid chromatography/electrospray ionization mass spectrometry

To control and identify with confidence the principal enological tannins (ETs), we have devised a specific method based on the characterization of proanthocyanidin composition. We started by controlling the red colouring produced by hydrochloric acid butanolysis (e.g. Bate-Smith reaction), due to the formation of anthyocyanidins, typical of proanthocyanidin tannins. Using thioacidolysis/liquid chromatography/electrospray ionization mass spectrometry we were able to identify: (i) the nature of the flavan-3-ols (catechin, epicatechin for procyanidins tannins; gallocatechin, epigallocatechin for prodelphinidins tannins), (ii) the degree of galloylation, (iii) the average degree of polymerization (mDP). We also performed a complete structural study by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS). By comparing the chromatographic profiles of standard proanthocyanidins prepared in our laboratory with those of a variety of commercial enological tannins, we were able to identify their origin: seed proanthocyanidins (PA): only procyanidins, high level of galloylation, with a large amount of epicatechin, and a low mDP corresponding to a majority of oligomeric tannins; skins PA: a mixture of procyanidins and prodelphinidins, with a predominance of procyanidins, a low level of galloylation, with a large amount of epicatechin, and a very variable mDP; stems PA, mixture of procyanidins and prodelphinidins, little galloylation, with a very low level of epicatechin in the terminal unit, and a medium value for mDP (>5); Quebracho PA: results show no known flavan-3-ols, and according to MALDI-TOF-MS, the main structure is attributed to a large amount of profisetinidin, corresponding to a resorcinol proanthocyanidin.     

Direct introduction of a hydrazide group into a quartz crystal microbalance surface with dodecanoic hydrazide embedded in a hybrid bilayer membrane

Hydrazide group has a potential of immobilizing an antibody on a sensor surface in a way that ensures an optimal orientation and efficiency of the antibody. However, a multi-step chemical process, required for the preparation of a hydrazide group, is a barrier to its extensive application. This paper describes a new method to introduce a hydrazide group to a sensor surface by a one-step process using dodecanoic hydrazide. The method is based on an ability of the dodecanoic hydrazide to be incorporated into a hybrid bilayer membrane (HBM) layer, thereby presenting its hydrazide group to the surface. Liposome containing dodecanoic hydrazide was added to a hydrophobic self-assembled monolayer surface of a quartz crystal microbalance for the formation of a HBM. Then, the hydrazide group, presented in the surface of the HBM layer, was utilized for the oriented immobilization of an antibody via its carbohydrate moiety which was partially oxidized prior to the conjugation reaction. Activity and stable status of the incorporated dodecanoic hydrazide was revealed by the efficiency and reproducibility of the resulting immunosensor chip.     

Asymmetric membrane formation via immersion precipitation method. I. Kinetic effect

The kinetic effect of the phase inversion process on the membrane morphology is explored, with emphasis on the diffusion coefficient of the nonsolvent as a measure of the solvent/nonsolvent exchange rate. The diffusion coefficient is closely related to the nonsolvent tolerance of the polymer solution, which was estimated from a pseudo-ternary phase diagram of the following system: polymer: polysulfone; solvent system: a mixture of the solvent 1-methyl-2-pyrrolidinone and a solvent additive (formic acid, water or ethanol); and nonsolvent: ethanol. Regardless of the kind of solvent additive employed, when the diffusion coefficient of the nonsolvent is high for a given gelation medium, then the membrane consists of a smooth, defect-free surface and macrovoid-free cross section, and is highly permeable to oxygen. However, using a polymer solution with a low diffusion coefficient results in a membrane of a rather defective morphology. Therefore, it is concluded that the diffusion coefficient of the nonsolvent is a crucial parameter in controlling membrane morphology.     

New Method for Obtaining a Bioactive Essence Extracted from Iberian Ham Fat Rich in MUFA and Antioxidants

Iberian ham is one of the most representative Spanish products and presents an excellent nutritional and sensory quality. Iberian ham trimming fat is considered a by-product and to give a new use to this remaining part could represent a healthy and innovative option for obtaining sustainable foods. The purpose of this work was to obtain a new bioactive ingredient from Iberian ham trimming fat with the highest amount of antioxidants and monounsaturated fatty acids (MUFA), using a new non-invasive solvent-free method. To obtain the essence, two different extraction procedures were carried out. After fatty acid characterization, degree of acidity, peroxide index and a basic sensory analysis were performed. Antioxidant in vitro activity and total phenolic compounds (TPC) were also determined. This new ingredient showed a better sensory profile than raw ham fat, a lower degree of acidity, a higher content of MUFAs, and also showed a higher antioxidant capacity and an increase in phenolic compounds compared to the raw material. This bioactive essence could be used as a food, a cosmetic or a nutraceutical ingredient to prevent certain diseases related to oxidative stress and could also contribute to the maintenance of the circular economy.     

In Pursuit of a Competitive Target: Total Synthesis of the Antibiotic Kendomycin

Kendomycin is a novel polyketide having a unique quinone methide ansa structure and an impressive biological profile. Herein we provide a chronological overview of the synthetic work towards the title compound. Thus far, over a period of about eight years, eight groups worldwide have published on their synthetic efforts resulting in five total syntheses, one formal synthesis, and a number of fragment syntheses. Most approaches roughly mimic the biogenetic pathway, starting with an aromatic polyphenol subunit to which a polyketide chain is attached. Subsequent key steps include macrocyclization and the formation of the densely substituted tetrahydropyran ring, and then a late‐stage oxidation and lactol formation.     

Superiority of a new gradient system utilizing a critical threshold for the adsorption capacity of polypeptides to column packing when compared with a standard gradient system for the simultaneous and quantitative analysis of polypeptides

Compared with a standard gradient system, the new gradient system which we developed has a major advantage because it permits a wide range of acetonitrile content, e.g. more than the critical threshold, in the polypeptide solution and allows the quantitative analysis of the polypeptide with satisfactory analytical precision. Additionally, this new gradient system allows the enhancement of the sensitivity of the polypeptide analysis proportionate to the increased volume of solution loaded with the same levels of precision. In contrast, when using a standard gradient system it is difficult to analyze a polypeptide quantitatively with good precision due to either adsorption to various materials or to irregular change in the ratio between a retained and a passed peak of the polypeptide. Additionally, the appearance of a passed peak results in a loss in the sensitivity of the polypeptide analysis, although no adsorption of a polypeptide to various materials occurs in a solution with acetonitrile content more than the critical threshold. Consequently, the new gradient system is effective for the simultaneous and quantitative analysis of different polypeptides with good precision and without any loss of sensitivity due to either adsorption to various materials or the appearance of a passed peak.