排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Lucía Tapia Yolanda Prez Michael Bolte Josefina Casas Jordi Sol Roberto Quesada Ignacio Alfonso 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12595-12598
Acidic microenvironments in solid tumors are a hallmark of cancer. Inspired by that, we designed a family of pseudopeptidic cage‐like anionophores displaying pH‐dependent activity. When protonated, they efficiently bind chloride anions. They also transport chloride through lipid bilayers, with their anionophoric properties improving at acidic pH, suggesting an H+/Cl? symport mechanism. NMR studies in DPC micelles demonstrate that the cages bind chloride within the lipid phase. The chloride affinity and the chloride‐exchange rate with the aqueous bulk solution are improved when the pH is lowered. This increases cytotoxicity towards lung adenocarcinoma cells at the pH of the microenvironment of a solid tumor. These properties depend on the nature of the amino‐acid side chains of the cages, which modulate their lipophilicity and interactions with the cell membrane. This paves the way towards using pH as a parameter to control the selectivity of cytotoxic ionophores as anticancer drugs. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(1):164-168
Herein we report the organoplatinum‐mediated bottom‐up synthesis, characterization, and properties of a novel large π‐extended carbon nanoring based on a nanographene hexa‐peri ‐hexabenzocoronene (HBC) building unit. This tubular structure can be considered as an example of the longitudinal extension of the cycloparaphenylene scaffold to form a large π‐extended carbon nanotube (CNT) segment. The cyclic tetramer of a tetramesityl HBC ([4]CHBC) was synthesized by the reaction of a 2,11‐diborylated hexa‐peri ‐hexabenzocoronene with a platinum complex, followed by reductive elimination. The structure of this tubular molecule was further confirmed by physical characterization. Theoretical calculations indicate that the strain energy of this nanoring is as high as 49.18 kcal mol−1. The selective supramolecular host–guest interaction between [4]CHBC and C70 was also investigated. 相似文献
3.
Min Tu Helge Reinsch Sabina Rodríguez‐Hermida Rhea Verbeke Timothe Stassin Werner Egger Marcel Dickmann Bjorn Dieu Johan Hofkens Ivo F. J. Vankelecom Norbert Stock Rob Ameloot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2445-2449
Metal–organic frameworks (MOFs) enable the design of host–guest systems with specific properties. In this work, we show how the confinement of anthracene in a well‐chosen MOF host leads to reversible yellow‐to‐purple photoswitching of the fluorescence emission. This behavior has not been observed before for anthracene, either in pure form or adsorbed in other porous hosts. The photoresponse of the host–guest system is caused by the photodimerization of anthracene, which is greatly facilitated by the pore geometry, connectivity, and volume as well as the structural flexibility of the MOF host. The photoswitching behavior was used to fabricate photopatternable and erasable surfaces that, in combination with data encryption and decryption, hold promise in product authentication and secure communication applications. 相似文献
4.
Victor Martínez‐Agramunt Tobias Eder Heidar Darmandeh Gregorio Guisado‐Barrios Eduardo Peris 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5738-5742
A palladium‐cornered molecular square with four pyrene‐bis(imidazolylidene) bridging ligands is reported. This metallo‐polygon can encapsulate C60 and C70. The X‐ray diffraction structures of the empty cage as well as the cages complexed with both fullerenes are described. The fullerene encapsulation produces perturbations in the structural parameters of the metallo‐square, showing that it can adjust the shape of its cavity to the size of each fullerene. 相似文献
5.
Luis Escobar Eduardo C. Escudero‐Adn Pablo Ballester 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16251-16255
Planar pyridyl N‐oxides are encapsulated in mono‐metallic PdII/PtII‐cages based on a tetra‐pyridyl calix[4]pyrrole ligand. The exchange dynamics of the cage complexes are slow on both the NMR chemical shift and EXSY timescales, but encapsulation of the guests by the cages is fast on the human timescale. A “French doors” mechanism, involving the rotation of the meso‐phenyl walls of the cages, allows the passage of the planar guests. The encapsulation of quinuclidine N‐oxide, a sterically more demanding guest, is slower than pyridyl N‐oxides in the PdII‐cage, and does not take place in the PtII counterpart. A modification of the encapsulation mechanism for the quinuclidine N‐oxide is postulated that requires the partial dissociation of the PdII‐cage. The substrate binding selectivity featured by the cages is related to their different guest uptake/release mechanisms. 相似文献
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Qing Li Dr. Kecheng Jie Prof. Dr. Feihe Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(13):5393-5396
The production of high purity toluene and pyridine is of significance in both industrial production and synthetic chemistry. The present protocols available to separate toluene/pyridine mixtures are several energy-intensive distillation methods, which are not environmentally friendly and cost-effective. Herein, we provide an energy-efficient and simple adsorptive separation protocol using nonporous adaptive crystals of cucurbit[6]uril ( Q[6] ). Q[6] crystals separate pyridine from toluene/pyridine mixtures with nearly 100 % purity. Furthermore, removal of the guest from guest-loaded Q[6] leads to the guest-free cucurbit[6]uril, which can be recycled without losing performance. 相似文献
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Xinglong Zhou Zhen Shen Beibei Ma Zhenqiang Xia Yingying Chai Xiaojie Ju Liangyin Chu Ridong Huang Hai Chen Weimin Li Yang He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9703-9712
Confining polar water molecules to particular geometries demands sophisticated intermolecular interactions, and not many small synthetic molecules have accomplished such a task. Herein, regioisomeric acyclic Janus‐AT nucleosides ( 1 and 2 ), with a self‐complementary fused genetic alphabet and conformationally flexible side chains, have been selectively synthesized. 1 and 2 adopt disparate base‐pair motifs from the π–π stacked hydrophobic base moieties and distinct hydrogen bond (HB) interconnections from the hydrophilic sugar residues, which in turn lead to divergent, intricate intermolecular interaction networks with different capacities to confine water molecules. Under the precise control of the host framework of the N8‐regioisomer, separate ordered single‐file water wires can be locked through special three‐HB clamps into unique inter‐ and intra‐wire geometrical alignments. Localized dynamic synchronized rotations within the fixed framework coordinated by both the host hydroxy groups and guest water molecules were observed in a temperature‐induced reversible single‐crystal‐to‐single‐crystal transition (SCSCT). 相似文献
10.
Chao Jing Bodong Zhang Sabine Synkule Maryam Ebrahimi Alexander Riss Willi Auwrter Li Jiang Guillaume Mdard Joachim Reichert Johannes V. Barth Anthoula C. Papageorgiou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19124-19132
Linear modules equipped with two terminal hydroxamic acid groups act as the building block of diverse two‐dimensional supramolecular motifs and patterns with room‐temperature stability on the close‐packed single‐crystal surfaces of silver and gold, revealing a complex self‐assembly scenario. By combining multiple investigation techniques (scanning tunneling microscopy, atomic force microscopy, X‐ray photoelectron spectroscopy, and density functional theory calculations), we analyze the characteristics of the ordered assemblies which range from close‐packed structures to polyporous networks featuring an exceptionally extended primitive unit cell with a side length exceeding 7 nm. The polyporous network shows potential for hosting and promoting the formation of chiral supramolecules, whereas a transition from 1D chiral randomness to an ordered racemate is discovered in a different porous phase. We correlate the observed structural changes to the adaptivity of the building block and surface‐induced changes in the chemical state of the hydroxamic acid functional group. 相似文献