共查询到20条相似文献,搜索用时 15 毫秒
1.
Supramolecular [60]Fullerene Liquid Crystals Formed By Self‐Organized Two‐Dimensional Crystals
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)
Xiaoyan Zhang Dr. Chih‐Hao Hsu Dr. Xiangkui Ren Yan Gu Prof. Bo Song Dr. Hao‐Jan Sun Prof. Shuang Yang Prof. Erqiang Chen Prof. Yingfeng Tu Prof. Xiaohong Li Prof. Xiaoming Yang Prof. Yaowen Li Prof. Xiulin Zhu 《Angewandte Chemie (International ed. in English)》2015,54(1):114-117
Fullerene‐based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self‐organization and external‐field‐responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self‐organization driven by π–π interactions to form triple‐layer two‐dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals. 相似文献
2.
Kihong Lee Bonnie Choi Dr. Ilan Jen‐La Plante Maria V. Paley Xinjue Zhong Prof. Andrew C. Crowther Prof. Jonathan S. Owen Prof. Xiaoyang Zhu Prof. Xavier Roy 《Angewandte Chemie (International ed. in English)》2018,57(21):6125-6129
Two‐dimensional (2D) materials are commonly prepared by exfoliating bulk layered van der Waals crystals. The creation of synthetic 2D materials from bottom‐up methods is an important challenge as their structural flexibility will enable chemists to tune the materials properties. A 2D material was assembled using C60 as a polymerizable monomer. The C60 building blocks are first assembled into a layered solid using a molecular cluster as structure director. The resulting hierarchical crystal is used as a template to polymerize its C60 monolayers, which can be exfoliated down to 2D crystalline nanosheets. Derived from the parent template, the 2D structure is composed of a layer of inorganic cluster, sandwiched between two monolayers of polymerized C60. The nanosheets can be transferred onto solid substrates and depolymerized by heating. Electronic absorption spectroscopy reveals an optical gap of 0.25 eV, narrower than that of the bulk parent crystalline solid. 相似文献
3.
4.
Dr. Gabriella Cavallo Prof. Dr. Giancarlo Terraneo Alessandro Monfredini Dr. Marco Saccone Prof. Dr. Arri Priimagi Dr. Tullio Pilati Prof. Dr. Giuseppe Resnati Prof. Dr. Pierangelo Metrangolo Prof. Dr. Duncan W. Bruce 《Angewandte Chemie (International ed. in English)》2016,55(21):6300-6304
Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen‐bonded supramolecular anions [CnF2 n+1‐I???I???I‐CnF2 n+1]? are reported. The material system is unique in many ways, demonstrating for the first time 1) ionic, halogen‐bonded liquid crystals, and 2) imidazolium‐based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation. 相似文献
5.
Utilizing pure amine hydrogen bonding is a novel approach for constructing two‐dimensional (2D) networks. Further, such systems are capable of undergoing structural modifications due to changes in pH. In this study, we designed a 2D network of triaminobenzene (TAB) molecules that by varying the pH from neutral to acidic, form either ordered or disordered structures on Au(111) surface as revealed in scanning tunneling microscopy images. In near‐neutral solution (pH ≈5.5), protonation of TAB generates charged species capable of forming H‐bonds between amine groups of neighboring molecules resulting in the formation of a 2D supramolecular structure on the electrified surface. At lower pH, due to the protonation of the amine groups, intermolecular hydrogen bonding is no longer possible and no ordered structure is observed on the surface. This opens the possibility to employ pH as a chemical trigger to induce a phase transition in the 2D molecular network of triaminobenzene molecules. 相似文献
6.
7.
8.
《Chemphyschem》2003,4(5):474-481
Spectroscopic, computational, redox, and photochemical behavior of a self‐assembled donor‐acceptor dyad formed by axial coordination of zinc naphthalocyanine, ZnNc, and fulleropyrrolidine bearing an imidazole coordinating ligand (2‐(4′‐imidazolylphenyl)fulleropyrrolidine, C60Im) was investigated in noncoordinating solvents, toluene and o‐dichlorobenzene, and the results were compared to the intermolecular electron transfer processes in a coordinating solvent, benzonitrile. The optical absorption and ab initio B3 LYP/3–21G(*) computational studies revealed self‐assembled supramolecular 1:1 dyad formation between the ZnNc and C60Im entities. In the optimized structure, the HOMO was found to be entirely located on the ZnNc entity while the LUMO was found to be entirely on the fullerene entity. Cyclic voltammetry studies of the dyad exhibited a total of seven one‐electron redox processes in o‐dichlorobenzene, with 0.1 M tetrabutylammonium perchlorate. The excited‐state electron‐transfer processes were monitored by both optical‐emission and transient‐absorption techniques. Direct evidence for the radical‐ion‐pair (C60Im.?:ZnNc . + ) formation was obtained from picosecond transient‐absorption spectral studies, which indicated charge separation from the singlet‐excited ZnNc to the C60Im moiety. The calculated rates of charge separation and charge recombination were 1.4×1010 s?1 and 5.3×107 s?1 in toluene and 8.9×109 s?1 and 9.2×107 s?1 in o‐dichlorobenzene, respectively. In benzonitrile, intermolecular electron transfer from the excited triplet state of ZnNc to C60Im occurs and the second‐order rate constant (kqtriplet) for this quenching process was 5.3×108 M ?1 s?1. 相似文献
9.
Norma K. Minar Dr. Kun Hou Christian Westermeier Dr. Markus Döblinger Dr. Jörg Schuster Fabian C. Hanusch Dr. Bert Nickel Prof. Dr. Geoffrey A. Ozin Prof. Dr. Thomas Bein 《Angewandte Chemie (International ed. in English)》2015,54(26):7577-7581
A highly‐ordered 3D covalent fullerene framework is presented with a structure based on octahedrally functionalized fullerene building blocks in which every fullerene is separated from the next by six functional groups and whose mesoporosity is controlled by cooperative self‐assembly with a liquid‐crystalline block copolymer. The new fullerene‐framework material was obtained in the form of supported films by spin coating the synthesis solution directly on glass or silicon substrates, followed by a heat treatment. The fullerene building blocks coassemble with a liquid‐crystalline block copolymer to produce a highly ordered covalent fullerene framework with orthorhombic Fmmm symmetry, accessible 7.5 nm pores, and high surface area, as revealed by gas adsorption, NMR spectroscopy, small‐angle X‐ray scattering (SAXS), and TEM. We also note that the 3D covalent fullerene framework exhibits a dielectric constant significantly lower than that of the nonporous precursor material. 相似文献
10.
Supramolecular Columnar Liquid Crystals with Tapered‐Shape Simple Pyrazoles Obtained by Efficient Henry/Michael Reactions
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)
Hugo Blanco Verónica Iguarbe Prof. Joaquín Barberá Prof. José Luis Serrano Dr. Anabel Elduque Dr. Raquel Giménez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4924-4930
A straightforward synthesis of mesogenic pyrazoles starting from benzaldehydes by a combination of efficient Henry and Michael reactions led to novel supramolecular liquid crystals. The mesogens are fluorescent 3,5‐dimethyl‐4‐(di or trialkoxyphenyl)pyrazoles and, in spite of the tapered shape of these molecules and their structural simplicity (only one phenyl ring), columnar liquid‐crystal phases were formed that are stable at room temperature. The self‐assembled structure was studied by XRD and the columnar cross section contains two molecules on average with an antiparallel arrangement of pyrazoles interacting through hydrogen bonds. In contrast, the single‐crystal structure of a trimethoxy analog did not show hydrogen‐bonded pyrazoles but chains of head‐to‐tail arranged molecules. 相似文献
11.
12.
13.
Two‐Dimensional Skyrmion Lattice Formation in a Nematic Liquid Crystal Consisting of Highly Bent Banana 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)
Prof. Dr. Sungmin Kang Dr. Eun‐Woo Lee Tianqi Li Prof. Dr. Xiaobin Liang Prof. Dr. Masatoshi Tokita Prof. Dr. Ken Nakajima Prof. Dr. Junji Watanabe 《Angewandte Chemie (International ed. in English)》2016,55(38):11552-11556
We synthesized a novel banana‐shaped molecule based on a 1,7‐naphthalene central core that exhibits a distinct mesomorphism of the nematic‐to‐nematic phase transition. Both the X‐ray profile and direct imaging of atomic force microscopy (AFM) investigations clearly indicates the formation of an anomalous nematic phase possessing a two‐dimensional (2D) tetragonal lattice with a large edge (ca. 59 Å) directed perpendicular to the director in the low‐temperature nematic phase. One plausible model is proposed by an analogy of skyrmion lattice in which two types of cylinders formed from left‐ and right‐handed twist‐bend helices stack into a 2D tetragonal lattice, diminishing the inversion domain wall. 相似文献
14.
Supramolecular Columnar Liquid Crystals Formed by Hydrogen Bonding between a Clicked Star‐Shaped s‐Triazine and Benzoic Acids
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)
Beatriz Feringán Dr. Pilar Romero Prof. José Luis Serrano Dr. Raquel Giménez Dr. Teresa Sierra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8859-8866
A star‐shaped tris(triazolyl)triazine is shown to establish hydrogen‐bond interactions with polycatenar benzoic acids. The formation of hydrogen‐bonded triazine/acid complexes has been demonstrated both in solution and in bulk by different techniques. The complexes, mainly formed by nonmesogenic components, all show enantiotropic hexagonal columnar mesomorphism, which relies on the formation of hydrogen‐bond complexes in a triazine/acid ratio of 1:3. This approach combines the straightforward synthesis of a nonmesomorphic triazine core by click chemistry, and the preparation of a supramolecular complex, providing a much more convenient route than covalent synthesis to modify the periphery of triazine discotics and thus to modulate their functionality. 相似文献
15.
16.
本文综述了液晶二聚体、多爪型液晶及香蕉形液晶等几类非常规液晶材料的研究进展。结合笔者近几年的研究积累,着重介绍:(1)液晶二聚体的分子结构与液晶态结构及液晶二聚体所特有的奇偶效应与近晶多形性;(2)多爪型液晶的分子结构与液晶态结构的特点及由于兼有棒状分子与盘状分子的结构特点而具备的特殊的相变性质;(3)香蕉形液晶的分子结构与液晶态结构及香蕉形液晶所特有的手性与极化序。在介绍各类液晶材料的特点及研究热点的同时,围绕分子结构与液晶态结构的关系这一主题,深入讨论了各种液晶材料形成特殊分子排列及表现出特殊物理性质的机理。 相似文献
17.
Jacopo Vialetto Manos Anyfantakis Sergii Rudiuk Mathieu Morel Damien Baigl 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9243-9247
Control over particle interactions and organization at fluid interfaces is of great importance both for fundamental studies and practical applications. Rendering these systems stimulus‐responsive is thus a desired challenge both for investigating dynamic phenomena and realizing reconfigurable materials. Here, we describe the first reversible photocontrol of two‐dimensional colloidal crystallization at the air/water interface, where millimeter‐sized assemblies of microparticles can be actuated through the dynamic adsorption/desorption behavior of a photosensitive surfactant added to the suspension. This allows us to dynamically switch the particle organization between a highly crystalline (under light) and a disordered (in the dark) phase with a fast response time (crystallization in ≈10 s, disassembly in ≈1 min). These results evidence a new kind of dissipative system where the crystalline state can be maintained only upon energy supply. 相似文献
18.
19.
Dr. Brindaban Roy Nirupam De Prof. Krishna C. Majumdar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(46):14560-14588
Liquid crystals are ordered soft materials formed by self‐organized molecules and can potentially be used as new functional materials for electron‐, ion‐ or molecular‐transport; optical; and bio‐active materials. In particular, the columnar liquid crystals are promising candidates used in various optical and electronic devices. For this purpose, design and synthesis of unconventional materials are essential. In this review, we have summarized several approaches for the synthesis of columnar liquid crystals composed of various heterocyclic systems. We also outline their liquid crystalline and other relevant properties, and their suitability for applications in diverse fields. 相似文献
20.
Supramolecular Formation of Li+@PCBM Fullerene with Sulfonated Porphyrins and Long‐Lived Charge Separation
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yuki Kawashima Dr. Kei Ohkubo Dr. Hiroshi Okada Prof. Dr. Yutaka Matsuo Prof. Dr. Shunichi Fukuzumi 《Chemphyschem》2014,15(17):3782-3790
Lithium‐ion‐encapsulated [6,6]‐phenyl‐C61‐butyric acid methyl ester fullerene (Li+@PCBM) was utilized to construct supramolecules with sulfonated meso‐tetraphenylporphyrins (MTPPS4?; M=Zn, H2) in polar benzonitrile. The association constants were determined to be 1.8×105 M ?1 for ZnTPPS4?/Li+@PCBM and 6.2×104 M ?1 for H2TPPS4?/Li+@PCBM. From the electrochemical analyses, the energies of the charge‐separated (CS) states were estimated to be 0.69 eV for ZnTPPS4?/Li+@PCBM and 1.00 eV for H2TPPS4?/Li+@PCBM. Upon photoexcitation of the porphyrin moieties of MTPPS4?/Li+@PCBM, photoinduced electron transfer occurred to produce the CS states. The lifetimes of the CS states were 560 μs for ZnTPPS4?/Li+@PCBM and 450 μs for H2TPPS4?/Li+@PCBM. The spin states of the CS states were determined to be triplet by electron paramagnetic resonance spectroscopy measurements at 4 K. The reorganization energies (λ) and electronic coupling term (V) for back electron transfer (BET) were determined from the temperature dependence of kBET to be λ=0.36 eV and V=8.5×10?3 cm?1 for ZnTPPS4?/Li+@PCBM and λ=0.62 eV and V=7.9×10?3 cm?1 for H2TPPS4?/Li+@PCBM based on the Marcus theory of nonadiabatic electron transfer. Such small V values are the result of a small orbital interaction between the MTPPS4? and Li+@PCBM moieties. These small V values and spin‐forbidden charge recombination afford a long‐lived CS state. 相似文献