共查询到20条相似文献,搜索用时 31 毫秒
1.
Dr. Chuanming Wang Prof. Qiang Zhao Huibin Sun Prof. Fuyou Li Prof. Quli Fan Prof. Wei Huang 《Chemphyschem》2011,12(2):313-321
The diarylethene derivative 1,2‐bis‐(5′‐dimesitylboryl‐2′‐methylthieny‐3′‐yl)‐cyclopentene ( 1 ) containing dimesitylboryl groups is an interesting photochromic material. The dimesitylboryl groups can bind to F?, which tunes the optical and electronic properties of the diarylethene compound. Hence, the diarylethene derivative 1 containing dimesitylboryl groups is sensitive to both light and F?, and its photochromic properties can be tuned by a fluoride ion. Herein, we studied the substituent effect of dimesitylboron groups on the optical properties of both the closed‐ring and open‐ring isomers of the diarylethene molecule by DFT/TDDFT calculations and found that these methods are reliable for the determination of the lowest singlet excitation energies of diarylethene compounds. The introduction of dimesitylboron groups to the diarylethene compound can elongate its conjugation length and change the excited‐state properties from π→π* transition to a charge‐transfer state. This explains the modulation of photochromic properties through the introduction of dimesitylboron groups. Furthermore, the photochromic properties can be tuned through the binding of F? to a boron center and the excited state of the diarylethene compound is changed from a charge‐transfer state to a π→π* transition. Hence, a subtle control of the photochromic spectroscopic properties was realized. In addition, the changes of electronic characteristics by the isomerization reaction of diarylethene compounds were also investigated with theoretical calculations. For the model compound 2 without dimesitylboryl groups, the closed‐ring isomer has better hole‐ and electron‐injection abilities, as well as higher charge‐transport rates, than the open‐ring isomer. The introduction of dimesitylboron groups to diarylethene can dramatically improve the charge‐injection and ‐transport abilities. The closed isomer of compound 1 ( 1 C ) has the best hole‐ and electron‐injection abilities, whereas the charge‐transport rates of the open isomer of compound 1 ( 1 O ) are higher than those of 1 C . Importantly, 1 O is an electron‐accepting and ‐transport material. These results show that the diarylethene compound containing dimesitylboryl groups has promising potential to be applied in optoelectronic devices and thus is worth to be further investigated. 相似文献
2.
Christoph Jurissek Fabian Berger Fabian Eisenreich Michael Kathan Stefan Hecht 《Angewandte Chemie (International ed. in English)》2019,58(7):1945-1949
The transfer of stereoinformation is at the heart of asymmetric reactions. By incorporating the natural monoterpene l ‐menthone into the backbone of a diarylethene, we achieved efficient chirality transfer upon photocyclization, resulting in the preferred formation of one major closed isomer in a diastereomeric ratio (d.r.) of 85:15. More significantly, we were able to completely reverse the diastereomeric outcome of the ring closure simply by altering the chemical environment or the irradiation conditions. As a result, we could selectively accumulate the less favored minor closed isomer, with remarkable d.r. values of >99:1 and 74:26, respectively. Computations revealed that a stability inversion after photocyclization is the basis for the observed unprecedented control over diastereoselectivity. 相似文献
3.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8783-8788
Physical fabrication of chiral metallic films usually results in singular or large‐sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule‐induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer‐sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption‐ and scattering‐based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices. 相似文献
4.
Takaya Kimoto Dr. Nobuo Tajima Prof. Dr. Michiya Fujiki Dr. Yoshitane Imai 《化学:亚洲杂志》2012,7(12):2836-2841
The solution‐dispersed‐state and polymer‐dispersed‐state circular dichroism (CD) and circularly polarized luminescence (CPL) properties of chiral binaphthyl fluorophores could be controlled by the choice of open‐ or closed‐type substituents on the binaphthyl units and by the axial chirality of the binaphthyls. 相似文献
5.
Photomobile Polymer Materials: Photoresponsive Behavior of Cross‐Linked Liquid‐Crystalline Polymers with Mesomorphic Diarylethenes
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jun‐ichi Mamiya Akito Kuriyama Naoki Yokota Dr. Munenori Yamada Prof. Dr. Tomiki Ikeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3174-3177
Cross‐linked liquid‐crystalline (LC) polymers with a mesomorphic diarylethene were prepared to demonstrate a versatile strategy for cross‐linked photochromic LC polymers as photomobile materials. Upon exposure to UV light to cause photocyclization of the diarylethene chromophore, the cross‐linked polymer films bend toward an actinic light source. By irradiation with visible light to cause a closed‐ring to open‐ring isomerization, the bent films revert to the initial flat state. Without visible‐light irradiation, the bent films remain bent even at 120 °C, indicating high thermal stability of the cross‐linked diarylethene LC polymers. 相似文献
6.
Chirality Relay in 2,2′‐Substituted 1,1′‐Binaphthyl: Access to Propeller Chirality of the Tricoordinate Boron Center
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chen Wang Zuo‐Bang Sun Qing‐Wen Xu Prof. Dr. Cui‐Hua Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16750-16754
It is a challenging issue to achieve propeller chirality for triarylboranes owing to the low transition barrier between the P and M forms of the boron center. Herein, we report a new strategy to achieve propeller chirality of triarylboranes. It was found that the chirality relay from axially chiral 1,1′‐binaphthyl to propeller chirality of the trivalent boron center can be realized when a Me2N and a Mes2B group (Mes=mesityl) are introduced at the 2,2′‐positions of the 1,1′‐binaphthyl skeleton ( BN‐BNaph ) owing to the strong π–π interaction between the Me2N‐bonded naphthyl ring and the phenyl ring of one adjacent Mes group, which not only exerts great steric hindrance on the rotation of the two Mes groups but also gives unequal stability to the two configurations of the boron center for a given configuration of the binaphthyl moiety. The stereostructures of the boron center were fully characterized through 1H NMR spectroscopy, X‐ray crystal analyses, and theoretical calculations. Detailed comparisons with the analog BN‐Ph‐BNaph , in which the Mes2B group is separated from 1,1′‐binaphthyl by a para‐phenylene spacer, confirmed the essential role of π–π interaction for the successful chirality relay in BN‐BNaph . 相似文献
7.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(41):12808-12812
Higher‐order super‐helical structures derived from biological molecules are known to evolve through opposite coiling of the initial helical fibers, as seen in collagen protein. A similar phenomenon is observed in a π‐system self‐assembly of chiral oligo(phenyleneethylene) derivatives (S )‐ 1 and (R )‐ 1 that explains the unequal formation of both left‐ and right‐handed helices from molecule having a specific chiral center. Concentration‐ and temperature‐dependent circular dichroism (CD) and UV/Vis spectroscopic studies revealed that the initial formation of helical aggregates is in accordance with the molecular chirality. At the next level of hierarchical self‐assembly, coiling of the fibers occurs with opposite handedness, thereby superseding the command of the molecular chirality. This was confirmed by solvent‐dependent decoiling of super‐helical structures and concentration‐dependent morphological analysis. 相似文献
8.
Sonia Sharma Meenal Kataria Manoj Kumar Vandana Bhalla 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16349-16355
The development of synthetic helical structures undergoing stimuli‐responsive chirality transformations is important for an understanding of the role of chirality in natural systems. However, controlling supramolecular chirality in entropically driven assemblies in aqueous media is challenging. To develop stimuli‐responsive assemblies, we designed and synthesized pyrazine derivatives with l ‐alanine groups as chiral building blocks. These systems undergo self‐assembly in aqueous media to generate helical fibers and the embedded alanine groups transfer their chirality to the assembled structures. Furthermore, these helical fibers undergo a Ni2+‐induced chirality transformation. The study demonstrates the role of intermolecular hydrogen bonding, π–π stacking, and the hydrophobic effect in the Ni2+‐mediated transition of helical fibers to supercoiled helical ensembles which mimic the formation of superstructures in biopolymers. 相似文献
9.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):30-37
The exploitation of the asymmetry at silicon in stereoselective synthesis is an exceptionally challenging task. Initially, silicon‐stereogenic silanes have been utilized to elucidate the stereochemical course of substitution reactions at silicon. Apart from these mechanistic investigations, only a handful of synthetic applications with an asymmetrically substituted silicon as the stereochemical controller have been reported to date. In these transformations the chiral silicon functions as a chiral auxiliary. Conversely, a direct transfer of chirality from silicon to carbon during bond formation and cleavage at silicon has remained open until its recent realization in both inter‐ and intramolecular reactions. In this Concept, the pivotal considerations in relation to the nature of suitable silanes as well as mechanistic prerequisites for an efficient chirality transfer will be discussed. 相似文献
10.
Simultaneous Induction of Axial and Planar Chirality in Arene–Chromium Complexes by Molybdenum‐Catalyzed Enantioselective Ring‐Closing Metathesis
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof.Dr. Ken Kamikawa Dr. Sachie Arae Dr. Wei‐Yi Wu Chihiro Nakamura Prof.Dr. Tamotsu Takahashi Prof.Dr. Masamichi Ogasawara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4954-4957
The molybdenum‐catalyzed asymmetric ring‐closing metathesis of the various Cs‐symmetric (π‐arene)chromium substrates provides the corresponding bridged planar‐chiral (π‐arene)chromium complexes in excellent yields with up to >99 % ee. With a bulky and unsymmetrical substituent, such as N‐indolyl or 1‐naphthyl, at the 2‐positions of the η6‐1,3‐diisopropenylbenzene ligands, both biaryl‐based axial chirality and π‐arene‐based planar chirality are simultaneously induced in the products. The axial chirality is retained even after the removal of the dicarbonylchromium fragment, and the chiral biaryl/heterobiaryl compounds are obtained with complete retention of the enantiopurity. 相似文献
11.
Benjamin Isare Dr. Mathieu Linares Dr. Loussiné Zargarian Dr. Serge Fermandjian Dr. Motofumi Miura Shigeyasu Motohashi Prof. Nicolas Vanthuyne Dr. Roberto Lazzaroni Dr. Laurent Bouteiller Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(1):173-177
Amplification of chirality has been reported in polymeric systems. It has also been shown that related effects can occur in polymer‐like dynamic supramolecular aggregates, if a subtle balance between noncovalent interactions allows the coupling between a chiral information and a cooperative aggregation process. In this context, we report a strong majority‐rules effect in the formation of chiral dynamic nanotubes from chiral bisurea monomers. Furthermore, similar helical nanotubes (with the same circular dichroism signature) can be obtained from racemic monomers in a chiral solvent. Competition experiments reveal the relative strength of the helical bias induced by the chiral monomer or by the chiral solvent. The nanotube handedness is imposed by the monomer chirality, whatever the solvent chirality. However, the chirality of the solvent has a significant effect on the degree of chiral induction. 相似文献
12.
Masahiro Fukuzumi Waka Nakanishi Tsutomu Ishikawa Takuya Kumamoto 《Helvetica chimica acta》2014,97(11):1453-1468
We report the synthesis and potential chirality of ortho‐phenylenebisguanidines (BGs) with substituents at C(3) and C(6). Guanidinylation of 3,6‐disubstituted benzene‐1,2‐diamines with 2‐chloro‐4,5‐dihydro‐1,3‐dimethyl‐1H‐imidazolium chloride gave the corresponding BGs. X‐Ray crystallography showed that the two guanidine moieties occupy different faces of the benzene ring, creating potential chirality, although optical resolution of tBu‐substituted BG by chiral HPLC failed. However, a methylated acyclic bisguanidinium salt (BGms) was obtained as a chiral crystal with a space group of P212121. 相似文献
13.
Chiral molecules, which may contain one or more different type(s) of stereocentres, such as central, axial, planar, and helical chiralities, etc., are indispensable in chemistry, pharmaceutical industry, and life science. Despite many advances for the preparation of chiral molecules usually with a single type of chirality have been realized, simultaneous construction of different types of chiralities is still a significant challenge. Here, we wish to report a protocol for preparation of chiral allenes with both central and axial chiralities via a catalytic asymmetric allenylation of different biologically or synthetically useful fluorinated or non‐fluorinated nucleophiles with readily available racemic allenes by using a single chiral ligand. An echoing between the central chirality and axial chirality for the enantioselectivity was observed. This strategy provides a general and practical approach to functionalized optically active allenes bearing both central and axial chiralities with an excellent enantioselectivity under mild conditions. 相似文献
14.
Characterization of Supramolecular Hidden Chirality of Hydrogen‐Bonded Networks by Advanced Graph Set Analysis
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Toshiyuki Sasaki Yoko Ida Dr. Ichiro Hisaki Dr. Tetsuharu Yuge Prof. Dr. Yoshiaki Uchida Dr. Norimitsu Tohnai Prof. Dr. Mikiji Miyata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(9):2478-2487
Supramolecular hidden chirality of hydrogen‐bonded (HB) networks of primary ammonium carboxylates was exposed by advanced graph set analysis from a symmetric viewpoint in topology. The ring‐type HB (R‐HB) networks are topologically regarded as faces, and therefore exhibit prochirality and positional isomerism due to substituents attached on the faces. To describe the symmetric properties of the faces, additional symbols, Re (right‐handed or clockwise), Si (left‐handed or anticlockwise), and m (mirror), were proposed. According to the symbols, various kinds of faces were classified based on the symmetry. This symmetry consideration of the faces enables us to precisely evaluate supramolecular chirality, especially its handedness, of 0D‐cubic, 1D‐ladder and 2D‐sheet HB networks that are composed of the faces. The 1D‐ladder and 2D‐sheet HB networks generate chirality by accumulating the chiral faces in 1D and 2D manners, respectively, whereas 0D‐cubic HB networks generate chirality based on combinations of eight kinds of faces, similar to the chirality of dice. 相似文献
15.
《化学:亚洲杂志》2017,12(15):1839-1850
Chiral nanomaterials have received wide interest in many areas, but the exact origin of chirality at the atomic level remains elusive in many cases. With recent significant progress in atomically precise gold nanoclusters (e.g., thiolate‐protected Aun (SR)m ), several origins of chirality have been unveiled based upon atomic structures determined by using single‐crystal X‐ray crystallography. The reported chiral Aun (SR)m structures explicitly reveal a predominant origin of chirality that arises from the Au–S chiral patterns at the metal–ligand interface, as opposed to the chiral arrangement of metal atoms in the inner core (i.e. kernel). In addition, chirality can also be introduced by a chiral ligand, manifested in the circular dichroism response from metal‐based electronic transitions other than the ligand's own transition(s). Lastly, the chiral arrangement of carbon tails of the ligands has also been discovered in a very recent work on chiral Au133(SR)52 and Au246(SR)80 nanoclusters. Overall, the origins of chirality discovered in Aun (SR)m nanoclusters may provide models for the understanding of chirality origins in other types of nanomaterials and also constitute the basis for the development of various applications of chiral nanoparticles. 相似文献
16.
Inversion of the Supramolecular Chirality of Nanofibrous Structures through Co‐Assembly with Achiral Molecules
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Guo‐Feng Liu Dr. Ling‐Yun Zhu Wei Ji Prof. Chuan‐Liang Feng Prof. Zhi‐Xiang Wei 《Angewandte Chemie (International ed. in English)》2016,55(7):2411-2415
To understand the behavior of chiral nanostructures, it is of critical importance to study how achiral molecules regulate the chirality of such nanostructures and what the main driving forces for the regulation processes are. In this work, the supramolecular chirality of helical nanofibers consisting of phenylalanine‐based enantiomers is inverted by achiral bis(pyridinyl) derivatives through co‐assembly. This inversion is mainly mediated by intermolecular hydrogen bonding interactions between the achiral additives and the chiral molecules, which may induce stereoselective interactions and different reorientations for the assembled molecules, as confirmed by calculations. This work not only exemplifies a feasible method to invert the helicity of chiral nanostructures by the addition of achiral molecules, but also provides a method to explore their functions in environments where chiral and achiral molecules are in close proximity. 相似文献
17.
Yong‐Bin Wang Quan‐Hao Wu Zhi‐Peng Zhou Shao‐Hua Xiang Yuan Cui Peiyuan Yu Bin Tan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13577-13581
Axially chiral 2‐arylpyrrole frameworks are efficiently accessed through a direct chirality transfer strategy by rapid cyclization of enantioenriched atropisomeric alkenes, which are generated by organocatalytic asymmetric N‐alkylation reactions. This approach accommodates a broad scope of substrates with remarkably high chirality transfer efficiency, affording novel atropisomers with a fully substituted pyrrole moiety and high enantiopurities. Given the enantioenriched atropisomeric alkenes, novel heterocyclic 2‐arylazepine atropisomers were realized through a rationally designed ene reaction. 相似文献
18.
Double Transfer of Chirality in Organocopper‐Mediated bis(Alkylating) Cycloisomerization of Enediynes
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Damien Campolo Dr. Tanzeel Arif Cyril Borie Dr. Dominique Mouysset Dr. Nicolas Vanthuyne Dr. Jean‐Valère Naubron Prof. Michèle P. Bertrand Dr. Malek Nechab 《Angewandte Chemie (International ed. in English)》2014,53(12):3227-3231
An original synthesis of chiral benzofulvenes triggered by organocopper reagents is reported. These enantiopure products are available through a highly chemo‐, regio‐, diastereo‐, and enantioselective bis(alkylating) cycloisomerization process. A double chirality transfer (central‐to‐axial‐to‐central) is observed. 相似文献
19.
Oestreich M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,12(1):30-37
The exploitation of the asymmetry at silicon in stereoselective synthesis is an exceptionally challenging task. Initially, silicon-stereogenic silanes have been utilized to elucidate the stereochemical course of substitution reactions at silicon. Apart from these mechanistic investigations, only a handful of synthetic applications with an asymmetrically substituted silicon as the stereochemical controller have been reported to date. In these transformations the chiral silicon functions as a chiral auxiliary. Conversely, a direct transfer of chirality from silicon to carbon during bond formation and cleavage at silicon has remained open until its recent realization in both inter- and intramolecular reactions. In this Concept, the pivotal considerations in relation to the nature of suitable silanes as well as mechanistic prerequisites for an efficient chirality transfer will be discussed. 相似文献
20.
Huangtianzhi Zhu Qi Li Zongchun Gao Hongliang Wang Bingbing Shi Yitao Wu Liqing Shangguan Xin Hong Feng Wang Feihe Huang 《Angewandte Chemie (International ed. in English)》2020,59(27):10868-10872
The contradiction between the rising demands of optical chirality sensing and the failure in chiral detection of cryptochiral compounds encourages researchers to find new methods for chirality amplification. Inspired by planar chirality and the host–guest recognition of pillararenes, we establish a new concept for amplifying CD signals of cryptochiral molecules by pillararene host–guest complexation induced chirality amplification. The planar chirality of pillararenes is induced and stabilized in the presence of the chiral guest, which makes the cryptochiral molecule detectable by CD spectroscopy. Several chiral guests are selected in these experiments and the mechanism of chiral amplification is studied with a non‐rotatable pillararene derivative and density functional theory calculations. We believe this work affords deeper understanding of chirality and provides a new perspective for chiral sensing. 相似文献