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81.
Pietro Tundo Alvise Perosa Maurizio Selva Ludovico Valli Cinzia Giannini 《Colloids and surfaces. A, Physicochemical and engineering aspects》2001,190(3):295-303
A new amphiphilic derivative of fullerene C60 bearing an oligoglycyl tail (C60CHCOgly2OEt, 2) formed stable Langmuir floating films at the air–water interface. This occurred when the molecular assembly was stabilized by anchoring the amphiphilic C60's to the aqueous subphase, via hydrogen bonding interactions between a dipeptide (Gly–L–Leu) dissolved in the water subphase, and the oligoglycyl chain. The compression (π−A) isotherm of the Langmuir floating film constructed in such a way showed no hysteresis, was steep, and evidenced that the monolayer collapsed at a surface pressure π65 mN m−1, thus confirming that the film was tightly packed, extremely stable, and rigid. A limiting area per molecule of 89.1 Å2 was extrapolated, in agreement with the calculated cross-section area of the C60 fullerene. On the contrary, when the dipeptide was absent and pure water was used as the subphase, the π−A isotherm yielded a limiting area <55 Å2 which indicated the formation of multiple layers; moreover it showed significant hysteresis, the film was fragile, and it collapsed at π≈50 mN m−1. Once anchored by the dipeptide, the floating monolayer of 2 could be transferred onto hydrophobic quartz, glass and silicon substrates, by successive vertical dipping cycles, each cycle made up of two down-strokes and two up-strokes, to yield the Langmuir–Blodgett film. Up to 200 down- and up-strokes could be repeated reproducibly, a noteworthy result for non-covalently assembled LB films of fullerenes. The transfer ratio was 1.0, except for the second down-stroke of each cycle that gave a transfer ratio of zero, making the sequence of successful transfers: D, U, U, (cleaning and spreading), D, U, U, (cleaning and spreading), and so on (D=down-stroke, U=up-stroke). The total number of deposited layers was therefore 150. X-ray diffraction spectra were registered and exhibited a peak, which was fitted by a Montecarlo method of simulation to obtain the distribution of the repeat unit responsible for scattering; such distribution, with thickness between 20 and 60 Å, was consistent with the size of the amphiphile and the transfer sequence. The UV–Vis spectra of the LB film exhibited the characteristic C60 bands, and the absorption peaks in the 200–400 nm range were proportional to the number of layers, indicating that the deposition was reproducible and that the molecular environment of C60 in each layer remained constant. 相似文献
82.
83.
《无机化学与普通化学杂志》2018,644(3):142-148
Three diacylthioureas 1,4‐C6H4[C(O)NHC(S)NHAr]2 (Ar = 2,6‐iPr2C6H3) ( L1 , 1 ), 1,3‐C6H4[C(O)NHC(S)NHAr]2 ( L2 , 2 ), and 1,3‐C6H4[C(O)NHC(S)NHAr′]2 (Ar′ = 2,6‐Me2C6H3) ( L3 , 3 ) were synthesized and characterized. The CuI complexes from the reactions of bipodal ligands Ln with CuX (X = Cl, Br, I) were structurally investigated by single‐crystal X‐ray diffraction methods. Treatment of L1 with CuX gave the metallamacrocyclic complexes ( L1 CuX)2 [X = Cl ( 4 ), Br ( 5 ), I ( 6 )] with the ligand to metal in a ratio of 2:2, where both sulfur and halide anions function as terminal substituents. In contrast, when L2 or L3 was reacted with CuBr, the two Ln ligands coordinate to four copper atoms each in a bridging and terminal fashion to yield [ Ln (CuBr)2]2 [n = 2 ( 7 ), 3 ( 8 )]. The obtained S4Cu4Br4 core contains all four bromide anions in bridging positions. The reaction of L3 with CuX (X = Cl, I) gave the 3:3 trinuclear complexes ( L3 CuX)3 [X = Cl ( 9 ) I ( 10 )], interconnected by halide bridges. The obtained diacylthioureas ( 1 – 3 ) and their CuI complexes ( 4 – 10 ) were also characterized by elemental analysis, FT‐IR, 1H and 13C NMR spectroscopy. 相似文献
84.
85.
Photo‐Controlled Reversible Microtubule Assembly Mediated by Paclitaxel‐Modified Cyclodextrin 下载免费PDF全文
Dr. Ying‐Ming Zhang Ni‐Yuan Zhang Kui Xiao Dr. Qilin Yu Prof. Dr. Yu Liu 《Angewandte Chemie (International ed. in English)》2018,57(28):8649-8653
The design and construction of multi‐stimuli‐responsive supramolecular nanoassemblies that can mimic and regulate the fundamental biological processes have become a focus of interest in supramolecular chemistry. In this work, a perfect combination has been achieved between naturally occurring microtubules and artificially macrocyclic receptors. The self‐assembling morphology of microtubules can be photo‐tuned by the host–guest interaction of paclitaxel‐modified β‐cyclodextrin (PTX‐CD) and photochromic arylazopyrazole (PTX‐AAP). Moreover, the supramolecularly aggregated microtubules in a cellular environment can induce a pronounced cell morphological change and cell death. This supramolecular approach based on the secondary PTX‐AAP?PTX‐CD complexation provides us a facile method to reversibly control the intertubular aggregation behaviors of microtubules, which may bring new perspectives in the treatment of diseases related to improper protein aggregation. 相似文献
86.
Formation of a Macrocycles‐in‐a‐Macrocycle Superstructure with All‐gauche Conformation by Reversible Radical Association 下载免费PDF全文
Dr. Liu Yuan Yi Han Prof. Tao Tao Dr. Hoa Phan Prof. Chunyan Chi 《Angewandte Chemie (International ed. in English)》2018,57(29):9023-9027
The formation of an unprecedented macrocycles‐in‐a‐macrocycle (MIM) superstructure by reversible radical–radical association of a triphenylamine based monomer terminated with three dicyanomethyl radicals is presented. The reaction yield is nearly quantitative and the obtained macrocycle contains three small dimeric macrocycles according to X‐ray crystallographic analysis. The six monomer molecules are linked by nine long dynamic covalent C(sp3)?C(sp3) bonds that all adopt a gauche conformation. Such a conformation favors the formation of a MIM structure rather than a 2D network with an all‐anti conformation. Two enantiomers with left‐/ right‐handed chirality exist in the single crystals of the superstructure. 相似文献
87.
《Journal of computational chemistry》2018,39(23):1931-1942
A tool for the automated assembly, molecular optimization and property calculation of supramolecular materials is presented. stk is a modular, extensible and open‐source Python library that provides a simple Python API and integration with third party computational codes. stk currently supports the construction of linear polymers, small linear oligomers, organic cages in multiple topologies and covalent organic frameworks (COFs) in multiple framework topologies, but is designed to be easy to extend to new, unrelated, supramolecules or new topologies. Extension to metal–organic frameworks (MOFs), metallocycles or supramolecules, such as catenanes, would be straightforward. Through integration with third party codes, stk offers the user the opportunity to explore the potential energy landscape of the assembled supramolecule and then calculate the supramolecule's structural features and properties. stk provides support for high‐throughput screening of large batches of supramolecules at a time. The source code of the program can be found at https://github.com/supramolecular-toolkit/stk . © 2018 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc. 相似文献
88.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(4):420-429
Polymerization‐induced self‐assembly (PISA) has become the preferred method of preparing self‐assembled nano‐objects based on amphiphilic block copolymers. The PISA methodology has also been extended to the realization of colloidal nanocomposites, such as polymer–silica hybrid particles. In this work, we compare two methods to prepare nanoparticles based on self‐assembly of block copolymers bearing a core‐forming block with a reactive alkoxysilane moiety (3‐(trimethoxysilyl)propyl methacrylate, MPS), namely (i) RAFT emulsion polymerization using a hydrophilic macroRAFT agent and (ii) solution‐phase self‐assembly upon slow addition of a selective solvent. Emulsion polymerization under both ab initio and seeded conditions were studied, as well the use of different initiating systems. Effective and reproducible chain extension (and hence PISA) of MPS via thermally initiated RAFT emulsion polymerization was compromised due to the hydrolysis and polycondensation of MPS occurring under the reaction conditions employed. A more successful approach to block copolymer self‐assembly was achieved via polymerization in a good solvent for both blocks (1,4‐dioxane) followed by the slow addition of water, yielding spherical nanoparticles that increased in size as the length of the solvophobic block was increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 420–429 相似文献
89.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(4):365-375
In this report, we synthesized poly(N‐vinyl imidazole) (PNVI) grafted silica nanoparticles (SiNP) by using RAFT polymerization through grafting‐from approach to demonstrate that the self‐assembled structure of SiNP is the key diving force in improving physical properties of SiNP based nanocomposites. In a multistep synthetic process, well‐defined PNVI chains with tunable molecular weights and surface chain densities were grown from the RAFT agent anchored SiNP surface using N‐vinyl imidazole (NVI) as a monomer. Spectroscopic and thermal analysis confirmed surface grafting of PNVI on SiNP surface and the amount of grafted PNVI chins were also quantified. The mean diameter of the PNVI grafted SiNP (PNVI‐g‐SiNP) particles altered between 50 and 100 nm with the variation of PNVI chain lengths. The present approach is metal‐catalyst free, straight forward, and provides PNVI functionalized SiNP in a simple manner in comparison to the reported methods. Further, these PNVI‐g‐SiNP particles were used as a nanofiller to prepare nanocomposites with Poly(4,4′‐diphenylether‐5,5′‐bibenzimidazole) (OPBI). These nanocomposites displayed significantly higher mechanical, proton conductivity and less acid leaching properties than the pristine OPBI. The anisotropic self‐assembled ordered structure formation of nanofillers in the nanocomposites believed to be the driving force for the enhanced physical properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 365–375 相似文献
90.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(14):1574-1583
Block and random copolymers of poly(3‐hexylthiophene) and poly[3‐(2‐(6‐carboxyhexyl)methyl)thiophene] with side‐chain carboxylic functionality ((P3HT‐b‐P3COOH) and (P3HT‐r‐P3COOH) were developed by Grignard Metathesis (GRIM) polymerization. The carboxylic functionality was introduced in the side chain via the oxazoline route. Both the block and random polythiophene copolymers were complexed with pyridine functionalized perylene bisimide to obtain supramolecular block and random polymer complexes. The complex formation in both systems was confirmed by 1H NMR, WXRD and SAXS studies. An expansion of d spacing upon complex formation was observed in both the block and random copolymer, which could be traced by WXRD. Hole and electron mobilities measured for the supramolecular complexes indicated values which were higher by an order of magnitude for the supramolecular block complex (μh ≈ 2.9 × 10−4 cm2/Vs; μe ≈ 3.1 × 10−6 cm2/Vs) as compared to the random (μh ≈ 1.4 × 10−5 cm2/Vs; μe ≈ 4.7 × 10−7 cm2/Vs) copolymer. These results are indicative of the higher degree of disorder prevailing in the films of random copolymer system compared to the block copolymer. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1574–1583 相似文献