共查询到20条相似文献,搜索用时 250 毫秒
1.
Hanna Jędrzejewska Michał Wierzbicki Dr. Piotr Cmoch Prof. Kari Rissanen Prof. Agnieszka Szumna 《Angewandte Chemie (International ed. in English)》2014,53(50):13760-13764
Owing to their versatility and biocompatibility, peptide‐based self‐assembled structures constitute valuable targets for complex functional designs. It is now shown that artificial capsules based on β‐barrel binding motifs can be obtained by means of dynamic covalent chemistry (DCC) and self‐assembly. Short peptides (up to tetrapeptides) are reversibly attached to resorcinarene scaffolds. Peptidic capsules are thus selectively formed in either a heterochiral or a homochiral way by simultaneous and spontaneous processes, involving chiral sorting, tautomerization, diastereoselective induction of inherent chirality, and chiral self‐assembly. Self‐assembly is shown to direct the regioselectivity of reversible chemical reactions. It is also responsible for shifting the tautomeric equilibrium for one of the homochiral capsules. Two different tautomers (keto‐enamine hemisphere and enol‐imine hemisphere) are observed in this capsule, allowing the structure to adapt for self‐assembly. 相似文献
2.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(45):14273-14277
Supramolecular self‐assembly of 24 forklike mesogenic ligands and 12 transition metal ions led to the formation of giant spherical coordination complexes that exhibit liquid‐crystalline (LC) phases. Self‐healing LC supramolecular gels were also obtained through the introduction of these LC nanostructured supramolecular giant spherical complexes into dynamic covalent networks formed by cross‐linkers and bifunctional polymers. The giant spherical structures of the PdII complexes with 72 rodlike moieties on the periphery were characterized by NMR, diffusion‐ordered NMR spectroscopy, and mass spectrometry. These complexes are stable and exhibit lyotropic LC behavior, while the mesogenic ligands show thermotropic LC properties. The self‐assembled LC structures of the spherical complexes can be tuned by the length of the rodlike moieties. 相似文献
3.
Marko M. L. Nieuwenhuizen Tom F. A. de Greef Dr. Rob L. J. van der Bruggen Jos M. J. Paulusse Dr. Wilco P. J. Appel Maarten M. J. Smulders Rint P. Sijbesma Prof. Dr. E. W. Meijer Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(5):1601-1612
Ureido‐pyrimidinone (UPy) dimers substituted with an additional urea functionality self‐assemble into one‐dimensional stacks in various solvents through lateral non‐covalent interactions. 1H NMR and DOSY studies in CDCl3 suggest the formation of short stacks (<10), whereas temperature‐dependent circular dichroism (CD) studies on chiral UPy dimers in heptane show the formation of much larger helical stacks. Analysis of the concentration‐dependent evolution of chemical shift in CDCl3 and the temperature‐dependent CD effect in heptane suggest that this self‐assembly process follows an isodesmic pathway in both solvents. The length of the aggregates is influenced by substituents attached to the urea functionality. In sharp contrast, UPy dimers carrying an additional urethane group do not self‐assemble into ordered stacks, as is evident from the absence of a CD effect in heptane and the concentration‐independent chemical shift of the alkylidene proton of the pyrimidinone ring in CDCl3. 相似文献
4.
Michel H. C. J. van Houtem Rafael Martín‐Rapún Dr. Jef A. J. M. Vekemans Dr. E. W. Meijer Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2258-2271
Two novel nonsymmetrical disc‐shaped molecules 1 and 2 based on 3,3′‐bis(acylamino)‐2,2′‐bipyridine units were synthesized by means of a statistical approach. Discotic 1 possesses six chiral dihydrocitronellyl tails and one peripheral phenyl group, whereas discotic 2 possesses six linear dodecyloxy tails and one peripheral pyridyl group. Preorganization by strong intramolecular hydrogen bonding and subsequent aromatic interactions induce self‐assembly of the discotics. Liquid crystallinity of 1 and 2 was determined with the aid of polarized optical microscopy, differential scanning calorimetry, and X‐ray diffraction. Two columnar rectangular mesophases (Colr) have been identified, whereas for C3‐symmetrical derivatives only one Colr mesophase has been found. 1 In solution, the molecularly dissolved state in chloroform was studied with 1H NMR spectroscopy, whereas the self‐assembled state in apolar solution was examined with optical spectroscopy. Remarkably, these desymmetrized discotics, which lack one aliphatic wedge, behave similar to the symmetric parent compound. To prove that the stacking behavior of discotics 1 and 2 is similar to that of reported C3‐symmetrical derivatives, a mixing experiment of chiral 1 with C3‐symmetrical 13 has been undertaken; it has shown that they indeed belong to one type of self‐assembly. This helical J‐type self‐assembly was further confirmed with UV/Vis and photoluminescence (PL) spectroscopy. Eventually, disc 2 , functionalized with a hydrogen‐bonding acceptor moiety, might perform secondary interactions with molecules such as acids. 相似文献
5.
Solvent‐Dependent Self‐Assembly Behaviour and Speciation Control of Pd6L8 Metallo‐supramolecular Cages 下载免费PDF全文
James J. Henkelis Dr. Julie Fisher Dr. Stuart L. Warriner Prof. Michaele J. Hardie 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):4117-4125
The C3‐symmetric chiral propylated host‐type ligands (±)‐tris(isonicotinoyl)‐tris(propyl)‐cyclotricatechylene ( L1 ) and (±)‐tris(4‐pyridyl‐4‐benzoxy)‐tris(propyl)‐cyclotricatechylene ( L2 ) self‐assemble with PdII into [Pd6L8]12+ metallo‐cages that resemble a stella octangula. The self‐assembly of the [Pd6( L1 )8]12+ cage is solvent‐dependent; broad NMR resonances and a disordered crystal structure indicate no chiral self‐sorting of the ligand enantiomers in DMSO solution, but sharp NMR resonances occur in MeCN or MeNO2. The [Pd6( L1 )8]12+ cage is observed to be less favourable in the presence of additional ligand, than is its counterpart, where L=(±)‐tris(isonicotinoyl)cyclotriguaiacylene ( L1 a ). The stoichiometry of reactant mixtures and chemical triggers can be used to control formation of mixtures of homoleptic or heteroleptic [Pd6L8]12+ metallo‐cages where L= L1 and L1 a . 相似文献
6.
Cécile Vigier‐Carrière Dr. Tony Garnier Déborah Wagner Dr. Philippe Lavalle Dr. Morgane Rabineau Dr. Joseph Hemmerlé Dr. Bernard Senger Prof. Pierre Schaaf Dr. Fouzia Boulmedais Dr. Loïc Jierry 《Angewandte Chemie (International ed. in English)》2015,54(35):10198-10201
The design and control of molecular systems that self‐assemble spontaneously and exclusively at or near an interface represents a real scientific challenge. We present here a new concept, an active seed layer that allows to overcome this challenge. It is based on enzyme‐assisted self‐assembly. An enzyme, alkaline phosphatase, which transforms an original peptide, Fmoc‐FFY(PO42?), into an efficient gelation agent by dephosphorylation, is embedded in a polyelectrolyte multilayer and constitutes the “reaction motor”. A seed layer composed of a polyelectrolyte covalently modified by anchoring hydrogelator peptides constitutes the top of the multilayer. This layer is the nucleation site for the Fmoc‐FFY peptide self‐assembly. When such a film is brought in contact with a Fmoc‐FFY(PO42?) solution, a nanofiber network starts to form almost instantaneously which extents up to several micrometers into the solution after several hours. We demonstrate that the active seed layer allows convenient control over the self‐assembly kinetics and the geometric features of the fiber network simply by changing its peptide density. 相似文献
7.
Aimei Gao Dr. Xinrui Miao Dr. Jie Liu Dr. Ping Zhao Dr. Jinwang Huang Dr. Wenli Deng Prof. Dr. 《Chemphyschem》2010,11(9):1951-1955
The synthesis and self‐assembly behavior of porphyrin–polypyridyl ruthenium(II) hybrid, which consists of a flexible alkyl chain attached with two conjugated moieties is described. The electronic absorption spectrum and emission spectra show that the [C8‐TPP‐(ip)Ru(phen)2](ClO4)2, abbreviated as (C8ip)TPPC has optical properties. Scanning tunneling microscopy (STM) studies found that the π–π interaction and metal–ligand interaction allow (C8ip)TPPC to form self‐assembled structure and have an edge‐on orientation on the highly oriented pyrolytic graphite (HOPG) surface. The multidentate structure in (C8ip)TPPC molecules act as linkers between the molecules and form metal–ligand coordination, which forces the assembly process in the direction of stable columnar arrays. In addition, although the sample was stored for two months in ambient conditions, STM experiments showed that the order of (C8ip)TPPC self‐assembly only slightly decreased which indicates that the self‐assembled monolayer is stable. This work demonstrates that introducing a metal‐ligand in the porphyrin‐polypyridyl compound is a useful strategy to obtain novel surface assemblies. 相似文献
8.
Self‐Assembly of Fullerene‐Based Janus Particles in Solution: Effects of Molecular Architecture and Solvent 下载免费PDF全文
Zhiwei Lin Pengtao Lu Chih‐Hao Hsu Dr. Kan Yue Dr. Xue‐Hui Dong Hao Liu Kai Guo Prof. Chrys Wesdemiotis Dr. Wen‐Bin Zhang Dr. Xinfei Yu Prof. Stephen Z. D. Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11630-11635
Two molecular Janus particles based on amphiphilic [60]fullerene (C60) derivatives were designed and synthesized by using the regioselective Bingel–Hirsh reaction and the click reaction. These particles contain carboxylic acid functional groups, a hydrophilic fullerene (AC60), and a hydrophobic C60 in different ratios and have distinct molecular architectures: 1:1 (AC60–C60) and 1:2 (AC60–2C60). These molecular Janus particles can self‐assemble in solution to form aggregates with various types of micellar morphology. Whereas vesicular morphology was observed for both AC60–C60 and AC60–2C60 in tetrahydrofuran, in a mixture of N,N‐dimethylformamide (DMF)/water, spherical micelles and cylindrical micelles were observed for AC60–C60 and AC60–2C60, respectively. A mechanism of formation was tentatively proposed based on the effects of molecular architecture and solvent polarity on self‐assembly. 相似文献
9.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(5):1264-1268
An inherently chiral C3‐symmetric triaminotribenzotriquinacene was condensed in racemic and enantiomerically pure form with a bis(salicylaldehyde) to form [2+3] salicylimine cage compounds. Investigations on the chiral self‐sorting revealed that while entropy favors narcissistic self‐sorting in solution, selective social self‐sorting can be achieved by exploiting the difference in solubility between the homochiral and heterochiral cages. Gas sorption measurements further showed that seemingly small structural differences can have a significant impact on the surface area of microporous covalent cage compounds. 相似文献
10.
《化学:亚洲杂志》2017,12(17):2258-2270
BF2‐chelated dipyrromethene, BODIPY, was functionalized to carry two styryl crown ether tails and a secondary electron donor at the meso position. By using a “two‐point” self‐assembly strategy, a bis‐alkylammonium‐functionalized fullerene (C60) was allowed to self‐assemble the crown ether voids of BODIPY to obtain multimodular donor–acceptor conjugates. As a consequence of the two‐point binding, the 1:1 stoichiometric complexes formed yielded complexes of higher stability in which fluorescence of BODIPY was found to be quenched; this suggested the occurrence of excited‐state processes. The geometry and electronic structure of the self‐assembled complexes were derived from B3LYP/3‐21G(*) methods in which no steric constraints between the entities was observed. An energy‐level diagram was established by using spectral, electrochemical, and computational results to help understand the mechanistic details of excited‐state processes originating from 1bis‐styryl‐BODIPY*. Femtosecond transient absorbance studies were indicative of the formation of an exciplex state prior to the charge‐separation process to yield a bis‐styryl‐BODIPY . +–C60 . − radical ion pair. The time constants for charge separation were generally lower than charge‐recombination processes. The present studies bring out the importance of multimode binding strategies to obtain stable self‐assembled donor–acceptor conjugates capable of undergoing photoinduced charge separation needed in artificial photosynthetic applications. 相似文献
11.
Thorben R. Schulte Julian J. Holstein Guido H. Clever 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5618-5622
Chiral nanosized confinements play a major role for enantioselective recognition and reaction control in biological systems. Supramolecular self‐assembly gives access to artificial mimics with tunable sizes and properties. Herein, a new family of [Pd2L4] coordination cages based on a chiral [6]helicene backbone is introduced. A racemic mixture of the bis‐monodentate pyridyl ligand L1 selectively assembles with PdII cations under chiral self‐discrimination to an achiral meso cage, cis‐[Pd2 L1P 2 L1M 2]. Enantiopure L1 forms homochiral cages [Pd2 L1P/M 4]. A longer derivative L2 forms chiral cages [Pd2 L2P/M 4] with larger cavities, which bind optical isomers of chiral guests with different affinities. Owing to its distinct chiroptical properties, this cage can distinguish non‐chiral guests of different lengths, as they were found to squeeze or elongate the cavity under modulation of the helical pitch of the helicenes. The CD spectroscopic results were supported by ion mobility mass spectrometry. 相似文献
12.
Yan Meng Xing Dai Minsi Xin Dr. Chuanjin Tian Hang Liu Prof. Mingxing Jin Prof. Zhigang Wang Prof. Rui‐Qin Zhang 《Chemphyschem》2014,15(13):2672-2675
We computationally study the transition process of a chiral difluorobenzo[c]phenanthrene (DFBcPh) molecule within non‐polar fullerene C260 to explore the confinement effect. We find blue‐shifts in the infrared and Raman spectra of the molecule inside the fullerene relative to those of isolated systems. Six types of spectrum features of the molecule appear in the 0–60 cm?1 band. Interestingly, the energy barrier of the chiral transformation of the molecule is elevated by 15.88 kcal mol?1 upon the confinement by the fullerene, indicating improvement in the stability of the enantiomers. The protection by C260 lowers the highest occupied molecular orbital energy level and lifts the lowest unoccupied molecular orbital energy level of the chiral molecule such that the chiral molecule is further chemically stabilized. We concluded that the confinement environment has an impact at the nanoscale on the enantiomer transformation process of the chiral molecule. 相似文献
13.
《Electroanalysis》2004,16(9):757-764
Colloidal Au particles have been deposited on the gold electrode through layer‐by‐layer self‐assembly using cysteamine as cross‐linkers. Self‐assembly of colloidal Au on the gold electrode resulted in an easier attachment of antibody, larger electrode surface and ideal electrode behavior. The redox reactions of [Fe(CN)6]4?/[Fe(CN)6]3? on the gold surface were blocked due to antibody immobilization, which were investigated by cyclic voltammetry and impedance spectroscopy. The interaction of antigen with grafted antibody recognition layers was carried out by soaking the modified electrode into a phosphate buffer at pH 7.0 with various concentrations of antigen at 37 °C for 30 min. Further, an amplification strategy to use biotin conjugated antibody was introduced for improving the sensitivity of impedance measurements. Thus, the sensor based on this immobilization method exhibits a large linear dynamic range, from 5–400 μg/L for detection of Human IgG. The detection limit is about 0.5 μg/L. 相似文献
14.
Grazia Cafeo Dr. Franz H. Kohnke Prof. Luca Valenti Andrew J. P. White Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(36):11593-11600
10α,20α‐Bis(4‐nitrophenyl)calix[4]pyrrole ( 1 ) forms 1:1 complexes with anions of selected aromatic hydroxy acids in which the host orientation within the guest is controlled by a change in the pH value. Some bis‐anionic guests, including those obtained from 4‐hydroxybenzoic acid, 1,4‐ and 1,3‐benzenedicarboxylic acids, induce the self‐assembly of molecular capsules involving two molecules of the receptor. 1H NMR data and solid‐state structures of the 1:1 complex of 1 with p‐C6H4(COOH)(COO?)+NMe4 and the 2:1 capsule [( 1 )2m‐C6H4(COO?)2(+NMe4)2] provide structural details in solution and in the solid state. 相似文献
15.
Elena G. Shcherbakova Dr. Tsuyoshi Minami Dr. Valentina Brega Prof. Dr. Tony D. James Prof. Dr. Pavel Anzenbacher Jr. 《Angewandte Chemie (International ed. in English)》2015,54(24):7130-7133
We report the first fluorescence‐based assay for the rapid determination of the ee value of amines, amino alcohols, and amino acid esters. The method uses the self‐assembly of 2‐formylphenylboronic acid with a chiral diol and a chiral amine or derivatives (of unknown chirality) to produce two diastereomeric iminoboronates that differ in their fluorescence intensity and polarization. The approach allows for the accurate determination of the ee value of chiral amines with errors of just 1–2 %. We believe that this application of orthogonal dynamic covalent self‐assembly in the determination of the enantioselectivity will lead to the development of high‐throughput procedures for the determination of chirality. 相似文献
16.
Dr. Ke Feng Dr. Mao‐Lin Yu Dr. Su‐Min Wang Dr. Ge‐Xia Wang Prof. Dr. Chen‐Ho Tung Prof. Dr. Li‐Zhu Wu 《Chemphyschem》2013,14(1):198-203
2‐Ureido‐4(1H)‐pyrimidinone‐bridged ferrocene–fullerene assembly I is designed and synthesized for elaborating the photoinduced electron‐transfer processes in self‐complementary quadruply hydrogen‐bonded modules. Unexpectedly, steady‐state and time‐resolved spectroscopy reveal an inefficient electron‐transfer process from the ferrocene to the singlet or triplet excited state of the fullerene, although the electron‐transfer reactions are thermodynamically feasible. Instead, an effective intra‐assembly triplet–triplet energy‐transfer process is found to be operative in assembly I with a rate constant of 9.2×105 s?1 and an efficiency of 73 % in CH2Cl2 at room temperature. 相似文献
17.
Silvia Suárez‐Suárez Prof. Gabino A. Carriedo Dr. Alejandro Presa Soto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(47):15933-15940
We describe a new and very versatile method to place chosen chemical functionalities at the edge of the pores of macroporous materials. The method is based on the synthesis and self‐assembly of inorganic block copolymers (BCPs) having chiral rigid segments bearing controllable quantities of randomly distributed functional groups. The synthesis of a series of optically active block copolyphosphazenes (PP) with the general formula [N?P(R‐O2C20H12)0.9(FG)0.2]n‐b‐[N?PMePh]m (FG=‐OC5H4N ( 6 ), ‐NC4H8S ( 7 ), and ‐NC4H8O ( 8 )), was accomplished by the sequential living cationic polycondensation of N‐silylphosphoranimines, using the mono‐end‐capped initiator [Ph3P?N?PCl3][Cl] ( 3 ). The self‐assembly of the phosphazene BCPs 6 – 8 led to chiral porous films. The functionality present on those polymers affected their self‐assembly behaviour resulting in the formation of pores of different diameters (Dn=111 ( 6 ), 53 ( 7 ) and 77 nm ( 8 )). The specific functionalisation of the pores was proven by decorating the films with gold nanoparticles (AuNPs). Thus, the BCPs 6 and 7 , having pyridine and thiomorpholine groups, respectively, were treated with HAuCl4, followed by reduction with NaBH4, yielding a new type of block copolyphosphazenes, which self‐assembled into chiral porous films specifically decorated with AuNPs at the edge of the pores. 相似文献
18.
Tuning the Chirality of Block Copolymers: From Twisted Morphologies to Nanospheres by Self‐Assembly 下载免费PDF全文
Silvia Suárez‐Suárez Prof. Gabino A. Carriedo Dr. Alejandro Presa Soto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):14129-14139
New advances into the chirality effect in the self‐assembly of block copolymers (BCPs) have been achieved by tuning the helicity of the chiral‐core‐forming blocks. The chiral BCPs {[N?P(R)‐O2C20H12]200?x[N?P(OC5H4N)2]x}‐b‐ [N?PMePh]50 ((R)‐O2C20H12=(R)‐1,1′‐binaphthyl‐2,2′‐dioxy, OC5H4N=4‐pyridinoxy (OPy); x=10, 30, 60, 100 for 3 a – d , respectively), in which the [N?P(OPy)2] units are randomly distributed within the chiral block, have been synthesised. The chiroptical properties of the BCPs ([α]D vs. T and CD) demonstrated that the helicity of the BCP chains may be simply controlled by the relative proportion of the chiral and achiral (i.e., [N?P(R)‐O2C20H12] and [N?P(OPy)2], respectively) units. Thus, although 3 a only contained only 5 % [N?P(OPy)2] units and exhibited a preferential helical sense, 3 d with 50 % of this unit adopted non‐preferred helical conformations. This gradual variation of the helicity allowed us to examine the chirality effect on the self‐assembly of chiral and helical BCPs (i.e., 3 a – c ) and chiral but non‐helical BCPs (i.e., 3 d ). The very significant influence of the helicity on the self‐assembly of these materials resulted in a variety of morphologies that extend from helical nanostructures to pearl‐necklace aggregates and nanospheres (i.e., 3 b and 3 d , respectively). We also demonstrate that the presence of pyridine moieties in BCPs 3 a – d allows specific decoration with gold nanoparticles. 相似文献
19.
A Smart Sensing Method for Object Identification Using Circularly Polarized Luminescence from Coordination‐Driven Self‐Assembly 下载免费PDF全文
Yuki Imai Yuka Nakano Prof. Tsuyoshi Kawai Dr. Junpei Yuasa 《Angewandte Chemie (International ed. in English)》2018,57(29):8973-8978
The potential use of circularly polarized luminescence for object identification in a sensor application is demonstrated. New luminescence probes using pyrene derivatives as sensor luminophores were developed. (R,R)‐Im2Py and (S,S)‐Im2Py contain two chiral imidazole moieties at 1,6‐positions through ethynyl spacers (angle between spacers ca. 180°). The probe molecules spontaneously self‐assemble into chiral stacks (P or M helicity) upon coordination to metal ions with tetrahedral coordination (Zn2+). The chiral probes display neither circular dichroism (CD) nor circularly polarized luminescence (CPL) without metal ions. However, (R,R)‐Im2Py and (S,S)‐Im2Py exhibit intense chiroptical activity (CD and CPL) upon self‐assembly with Zn2+ ions. (R,R)‐Im2Py and (S,S)‐Im2Py with chemical stimuli‐responsibility allow sensing using the CPL signal as detection output, enabling us to discriminate between a signal from the target analyte and that from non‐target species. 相似文献
20.
Direct Observation of Molecular‐Level Template Action Leading to Self‐Assembly of a Porous Framework
Sneha R. Bajpe Christine E. A. Kirschhock Prof. Alexander Aerts Dr. Eric Breynaert Dr. Gregory Absillis Tatjana N. Parac‐Vogt Prof. Lars Giebeler Dr. Johan A. Martens Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(13):3926-3932
The molecular steps involved in the self‐assembly of Cu3(BTC)2 (BTC=1,3,5‐benzenetricarboxylic acid) metal–organic frameworks that enclose Keggin‐type H3PW12O40 heteropolyacid molecules were unraveled by using solution 17O, 31P, and 183W NMR spectroscopy, small‐angle X‐ray scattering, near‐IR spectroscopy, and dynamic light scattering. In aqueous solution, complexation of Cu2+ ions with Keggin‐type heteropolyacids was observed. Cu2+ ions are arranged around the Keggin structure so that linking through benzenetricarboxylate groups results in the formation of the Cu3(BTC)2 MOF structure HKUST‐1. This is a unique instance in which a templating mechanism that relies on specific molecular‐level matching and leads to explicit nanoscale building units can be observed in situ during formation of the synthetic nanoporous material. 相似文献