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.     

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.     

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.     

Ordered nano-structure of a stamped self-organized protein layer on a HOPG surface using a HFB carrier

A groundbreaking method for ordered molecular layer preparation on a solid surface employing the drop-stamp method has been developed by us taking advantage of the characteristics of the HFB molecule as a self-organizer/adsorption carrier. It is a smart method which can be used to prepare a self-organized protein layer on a solid surface without unspecific adsorption or defects. In our previous report, we clarified the self-organizing nature of HFB-tagged protein molecules on a surface of a solution droplet. In this report, a protein layer was prepared on a HOPG surface by using the drop-stamp method with a maltose binding protein (MBP)-tagged HFBII molecule. The structure of the stamped protein layer was investigated using frequency modulation atomic force microscopy (FM-AFM) in a liquid condition. The FM-AFM images show that the drop-stamp method can prepare an ordered protein layer on a solid surface smartly. The drop-stamp method using a HFB carrier is a practical method which can be used to prepare an ordered protein layer on a solid substrate surface without unspecific adsorption defects.     

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 novel method that improves sensitivity of protein detection in PAGE and Western blot

We have developed a simple and inexpensive method that improves sensitivity of protein and antigen detection in standard PAGE procedures. Our technique uses a sample microloader device with a funnel‐like structure, filled with a 4% stacking gel. When attach to the top of a polyacrylamide slab gel, the proteins in a sample are concentrated by electrophoresis into a small volume as they emerge from the device's narrow outlet. Our microloader has several advantages over previous devices, including simple assembly, high versatility, and absence of cross‐contamination between lanes. Addition of this device to a slab gel results in a fivefold increase in the sensitivity of antigen detection in a Western blot. As a result, less protein is required for loading and signal detection. Our protocol is a straightforward modification of a standard experimental technique, and is especially useful when only limited sample quantities are available.     

Synthesis of well-defined polymers with protected silanol groups by atom transfer radical polymerization and their use for the fabrication of polymeric nanoparticles

Copper-mediated atom transfer radical polymerization (ATRP) of a protected silanol group-holding methacrylate, methacryloxypropyltrimethoxysilane (MOPS), was investigated. In a dry condition using carefully distilled solvent and monomer, the polymerization proceeded in a living fashion providing a low-polydispersity polymer with a predicted molecular weight. The ATRP in conjunction with the sequential monomer addition of methyl methacrylate (MMA) and MOPS afforded a block copolymer of the type PMMA-b-poly(MMA-r-MOPS). The heat treatment of a solution of the block copolymer in the presence of a catalytic amount of ammonia gave a polymeric core-shell nanoparticle with a shell of PMMA moieties and a core of the poly(MMA-r-MOPS) blocks cross-linked via the condensation of the trimethoxysilane groups of the MOPS moieties.     

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.     

Cyclic Ketones in Spiroannulation

Conversion of a cyclic carbonyl carbon into a quaternary carbon has been effected by a Wittig–Horner reaction with diethyl (N-benzyliden)aminomethylphosphonate and a subsequent alkylation with a protected vinyl ketone. The product was a substrate for spiroannulation after initial hydrolysis. The reaction sequence was carried out as a one-pot reaction.     

Solid-phase synthesis of 5-arylhistidines via a microwave-assisted Suzuki-Miyaura cross-coupling

Microwave irradiation efficiently promoted the solid-phase Suzuki-Miyaura reaction of a 5-bromohistidine with various arylboronic acids in the presence of a palladium catalyst. This methodology allowed the synthesis of peptides bearing a histidine residue substituted at position 5 of the imidazole ring with a phenyl, a substituted phenyl, a pyridyl, or a thienyl ring, as well as with the benzene ring of a tyrosine residue.     

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.     

Total Synthesis of Tetrodotoxin

A total synthesis of tetrodotoxin was accomplished. A Diels–Alder reaction between a known enone and a siloxy diene gave a tricyclic product, the steric bias of which was used to construct the remaining stereogenic centers. A nitrogen atom was introduced either by a four‐step sequence involving a Curtius rearrangement, or a three‐step sequence featuring a newly developed transformation of a terminal alkyne into a nitrile. Introduction of the guanidine moiety followed by the formation of the heterocyclic system by cascade reactions led to tetrodotoxin.     

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.     

超疏水表面上冷凝液滴发生弹跳的机制与条件分析

使用液滴合并前后的体积和表面自由能守恒作为两个限制条件,确定了合并液滴的初始形状,即为偏离平衡态的亚稳态液滴,具有缩小其底半径而向平衡态液滴转变的推动力.进而分析了液滴变形过程中的推动力和三相线(TPCL)上的滞后阻力,建立了液滴变形的动态方程并进行了差分求解.如果液滴能够变形至底半径为0mm的状态,则根据该状态下液滴重心上移的速度确定液滴的弹跳高度.不同表面上冷凝液滴合并后的变形行为的计算结果表明,光滑表面上的液滴合并后,液滴只能发生有限的变形,一般都在达到平衡态之前就停止了变形,因此冷凝液滴不会发生弹跳;粗糙表面上的Wenzel态液滴的三相线上的滞后阻力更大,因而液滴更难以变形和弹跳;具有微纳二级结构表面上只润湿微米结构,但不润湿纳米结构的部分Wenzel态液滴能够变形至Cassie态,但没有明显的弹跳;只有在纳米或微纳二级结构表面上的较小Cassie态液滴合并后,液滴易于变形至底半径为0mm的状态并发生弹跳.因此,Cassie态合并液滴处于亚稳态,并且其三相线上的移动阻力很小,是导致冷凝液滴弹跳的关键因素.     

Design of Phase‐Vanishing Reactions

Phase‐vanishing reactions utilize a perfluorinated solvent as a liquid membrane to separate a substrate and a reagent. Since their introduction less than ten years ago, phase‐vanishing reactions have become a valuable alternative to reactions that require a slow addition of a reagent. A variety of experimental designs allow reactions to be carried out under anhydrous conditions, under photolytic conditions, under solvent‐free conditions, with a gas as a reagent, and under reflux.     

Chemical adaptor systems

"Chemical adaptor systems" are molecules used to link different functionalities, based on unique reactivity that allows controlled fragmentation. Two different mechanistic reactivities were used to prepare chemical adaptor systems. The first is based on a spontaneous intra-cyclization reaction to form a stable ring molecule. Cleavage of the trigger generates a free nucleophile, for example, an amine group, which undergoes intra-cyclization to release the target molecule from the handle part (e.g., a targeting antibody or a solid support for synthesis). The second applied reactivity is an elimination reaction, which is usually based on a quinone-methide-type rearrangement. Similarly, cleavage of the trigger generates a free phenol functionality, which can undergo a self-elimination reaction through a quinone-methide rearrangement to release the target molecule. The adaptor molecules have been applied in the field of drug delivery to release a drug from a targeting device and in the field of solid-phase synthesis to release a synthetic molecule from the solid support. A chemical adaptor molecule has also been used as a building unit to construct dendrimers with a triggered fragmentation.     

Antiaromatic Sapphyrin Isomer: Transformation into Contracted Porphyrinoids with Variable Aromaticity

Sapphyrin is a pentapyrrolic expanded porphyrin with a 22π aromatic character. Herein, we report the synthesis of a 20π antiaromatic sapphyrin isomer 1 by oxidative cyclization of a pentapyrrane precursor P₅ with a terminal β-linked pyrrole. The resulting isomer 1 , containing a mis-linked bipyrrole unit in the skeleton, exhibits a reactivity for further oxidation due to the distinct antiaromatic electronic structure, affording a fused macrocycle 2 , possessing a spiro-carbon-containing [5.6.5.6]-tetracyclic structure. Subsequent treatment with an acid afforded a weakly aromatic pyrrolone-appended N-confused corrole 3 , and thermal fusion gave a [5.6.5.7]-tetracyclic-ring-embedded 14π aromatic triphyrin(2.1.1) analog 4 . The cyclization at the mis-linked pyrrole moiety of P₅ played a crucial role in synthesizing the antiaromatic porphyrinoid susceptible to facile transformation to novel porphyrinoids with variable aromaticity.     

Structural studies of biarylpyridines fluorophores lead to the identification of promising long wavelength emitters for use in fluorescent chemosensors

Fluorescent chemosensors—molecules whose fluorescence emission changes in response to a reversible binding event—require both a substrate binding domain and a reporting fluorophore. Our approach to chemosensor development is based on a combination of a new signaling mechanism and a modular fluorophore synthesis. The latter feature has facilitated detailed study of the properties of polyarylpyridine fluorophores, and has led to the identification of a visibly-emissive pyridine as a promising lead structure for chemosensor development. The results of this study are described herein.     

CSTR和批式反应器中酶法拆分萘普生的比较

比较了批式反应器和连续流动搅拌反应器中酶动力学拆分萘普生的不同之处。从宏观反应器平衡角度,推导出了在ＣＳＴＲ中不同于在批式反应器中的酶立体选择性,产物对映体过量值和反应转化率的定量关系式,并通过脂肪酶催化的萘一甲酯的不对称水解反应得到了证实。     

Single Quality Factor for Enthalpy-Entropy Compensation,Isoequilibrium and Isokinetic Relationships

Enthalpy-entropy compensation (EEC) is very often encountered in chemistry, biology and physics. Its origin is widely discussed since it would allow, for example, a very accurate tuning of the thermodynamic properties as a function of the reactants. However, EEC is often discarded as a statistical artefact, especially when only a limited temperature range is considered. We show that the likeliness of a statistical origin of an EEC can be established with a compensation quality factor (CQF) that depends only on the measured enthalpies and entropies and the experimental temperature range. This is directly derived from a comparison of the CQF with threshold values obtained from a large number of simulations with randomly generated Van ‘t Hoff plots. The value of CQF is furthermore a direct measure of the existence of a genuine isoequilibrium or isokinetic relationship.