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101.
Prof. Shinji Toyota Dr. Eiji Tsurumaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):6878-6890
Saturn-like systems consisting of nanoscale rings and spheres are fascinating motifs in supramolecular chemistry. Several ring molecules are known to include spherical molecules at the center of the cavity via noncovalent attractive interactions. In this Minireview, we generalize the molecular design, the structural features, and the supramolecular chemistry of such “nano-Saturns”, which consist of monocyclic rings and fullerene spheres (mainly C60), on the basis of previous experimental and theoretical studies. Ring molecules are classified into three types (loop, belt, and disk) according to their shapes and possible interactions. Whereas typical belt-shaped rings tend to form tight complexes due to the wide contact area via π–π interactions, flat disk-shaped rings generally form weak complexes due to the narrow contact area mainly via CH–π interactions. In spite of the small association energies, disk-shaped rings are attractive because such rings can mimic the planet Saturn precisely as exemplified by an anthracene cyclic hexamer–C60 complex. 相似文献
102.
Dr. Kai Wu Ya-Jun Hou Yu-Lin Lu Yan-Zhong Fan Ya-Nan Fan Dr. Hui-Juan Yu Dr. Kang Li Prof. Dr. Mei Pan Prof. Dr. Cheng-Yong Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11903-11909
Molecular or supramolecular level photoluminescence (PL) modulation combining chemical and photonic input/output signals together in an integrated system can provide potential high-density data memorizing and process functions intended for miniaturized devices and machines. Herein, a PL-responsive supramolecular coordination cage has been demonstrated for complex interactions with redox-active guests. PL signals of the cage can be switched and modulated by adding or retracting Fc derivatives or converting TTF into different oxidation states through chemical or photochemical pathways. As a result, reversible or stepwise PL responses are displayed by these host–guest systems because of the occurrence of photoinduced electron-transfer (PET) or fluorescence resonance energy transfer (FREnT) processes, providing unique nanodevice models bearing off/on logic gates or memristor-like sequential memory and Boolean operation functions. 相似文献
103.
In this report, CuO/MoS2 composites were successfully prepared by the hydrothermal method where nano‐sized CuO was uniformly distributed on the surface of hierarchical MoS2 substrates (CuO/MoS2 composites). Their physicochemical properties and catalytic performance in ammonium perchlorate (AP) decomposition were investigated and characterized by XRD, SEM, TEM, BET, XPS, TG/DSC and combustion measurement. The results showed that it could decrease AP decomposition temperature at high decomposition stage from 416.5 °C to 323.5 °C and increase the heat release from 378 J/g (pure AP) to 1340 J/g (AP with catalysts), which was better than pure CuO nanoparticles (345.5 °C and 1046 J/g). Meanwhile, it showed excellent performance in combustion reaction either in N2 or air atmosphere. The results obtained by photocurrent spectra, photoluminescence spectra and time‐resolved fluorescence emission spectra indicated that loading CuO mediated the generation rate and combination rate of electrons and holes, thus tuning the catalytic performance on AP decomposition. This study proved that employing the supports that can synergistically interact with CuO is an efficient strategy to enhance the catalytic performance of CuO. 相似文献
104.
Rocio Marilyn Caja Rivera 《Mathematical Methods in the Applied Sciences》2019,42(18):6810-6828
Vector‐borne diseases, such as leishmaniasis, dengue, malaria, and yellow fever, transmitted by microparasites show periodic fluctuations in their prevalence. The novelty of this research is to assess the relationship between the vector feeding preference for an infectious host and the annual seasonal transmission through a vector‐host mathematical model. For the first time, numerical simulations illustrate that by increasing the vector feeding preference value in the transmission dynamics, periodic fluctuations accentuate and the endemic equilibrium average increases in vector and host populations. Moreover, increasing the vector feeding preference value, the amplitude strengthens for the infectious host and vector populations. This periodic behavior shows a similar pattern with the Peruvian incidence data from 2000 to 2016 for Andean cutaneous leishmaniasis provided by the Ministry of Health of Peru (MINSA). In addition, using the Floquet theory, the time average method and the linear operator method provides for the first time that the basic reproduction number for a nonautonomous system depends explicitly on the vector feeding preference for the infectious host. The nonautonomous model system shows that is a threshold parameter for the local stability of the disease‐free periodic solution. Therefore, the vector feeding preference is an important factor that should be considered and attended to for future research. Public and veterinary health in Peru and other countries should consider the vector feeding preference for specific host to vector control. 相似文献
105.
The new tripeptide reported here is composed of (R)-2-(3-aminophenoxy)propionic acid and is a bowl-shaped receptor that simultaneously binds both cations and anions of acetylcholine chloride and benzyltrimethylammonium compounds. An intriguing conformational change of the host was observed in the complexation of the ionic pair, where anion-induced flipping of the amide group on the macrocycle occurred. 相似文献
106.
Da Quan Zhang Xing Jin Bin Xie Hyung Goun Joo Li Xin Gao Kang Yong Lee 《Surface and interface analysis : SIA》2012,44(1):78-83
The corrosion inhibition of ammonium heltamolybdate (AH) and calcium gluconate (CG) for AA6061 alloy in 3% NaCl solution was investigated by the electrochemical measurements. It indicates that AH inhibits the corrosion of AA6061 alloy and acts as an anodic inhibitor. Maximum inhibition efficiency reaches 74.3% at the concentration of 1 × 10?4 mol.l?1 AH. The results of the electrochemical studies reveal AH is physically adsorbed on the AA6061 alloy surface and the adsorption follows Langmuir isotherm. The combination of AH and CG enhances the inhibition efficiency to 95.9%. The enhanced inhibition is attributed to the promotion of AH adsorption by CG. The mixture of AH and CG is a mixed‐type inhibitor and renders the corrosion potential to more positive values. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
107.
Aurica Farcas Giulia Tregnago Ana‐Maria Resmerita Sarah Taleb Dehkordi Sophie Cantin Fabrice Goubard Pierre‐Henri Aubert Franco Cacialli 《Journal of polymer science. Part A, Polymer chemistry》2014,52(4):460-471
The photophysical properties of two polyrotaxanes ( PFBTh?PSβCD and PFBTh?PMeβCD ) composed of fluorene and bithiophene encapsulated into permodified β‐cyclodextrin cavities have been investigated and compared with those of the reference PFBTh . Rotaxane formation results in improvements of the thermal stability, solubility in common organic solvents, as well as better film forming ability combined with a high transparency. As expected PFBTh and its encapsulated forms absorb at wavelengths beyond 510 nm, and time‐resolved photoluminescence (PL) in solution shows a well‐define vibronic structures with a predominance of the 0‐0 transitions and an energy difference of 0.16 eV. The fluorescence lifetimes follow a monoexponential decay with a value τ = 630 ± 30 ps. Atomic force microscopy, AFM, indicated a tendency of polyrotaxanes to organize into fibers. The advancing contact angles indicated higher surface hydrophobicity and lower surface free‐energy values for polyrotaxanes compared with their unthreaded analogues. The device based on PFBTh?PSβCD: PCBM in a 1/1 w/w ratio under simulated AM 1.5G illumination at 100 mW cm?2 exhibited improved photovoltaic parameters of cells, resulted in high Voc (0.68 V), Jsc (1.65 mA cm?2), FF (31.6%), and PCE (0.35) values, compared with PFBTh or PFBTh?PMeβCD , respectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 460–471 相似文献
108.
Laiyan Bao 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1765-1771
Ammonium persulfate (APS), 2,2′‐azobis(amidinopropane) dihydrochloride (V50) and 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) were utilized to prepare temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPAM) microgels by precipitation polymerization under various reaction pH conditions. Their particle sizes and swelling ratios depended on the reaction pH due to the pH dependence on the ionization degree of the decomposed fragments originating from the initiators and their hydrophilicity‐hydrophobicity. The more hydrophobic initiator, under the reaction pH conditions used, could be partitioned to a greater extent into the microgel particles due to the hydrophobicity of PNIPAM chains at the reaction temperature, which led to a more cross‐linked structure inside the microgels resulting in their smaller swelling ratio. pH dependence of surface charge density of the microgels with amidino groups or carboxylic acid groups on their surfaces was evidenced by the variation of their zeta potentials as a function of pH. 相似文献
109.
110.
In this paper, 1,2-bis(2-acetamido-6-pyridyl)ethane, receptor 1, having an ethylene spacer is reported to recognise dicarboxylic acids. The binding study in the solution phase is carried out using 1H NMR (1:1) and UV–vis experiments and in the solid phase by single-crystal X-ray analysis. In 1H NMR, the downfield shifts of specific amide protons of receptor 1 in 1:1 complexes of receptor and guest diacids, and in the UV–vis experiment, the appearance of an isosbestic point as well as significant binding constants are observed, which thus unambiguously support the complexation of receptor 1 with dicarboxylic acids in solution. Receptor 2, simple 2-acetamido-6-methylpyridine, has lower binding constants than receptor 1 due to cooperative binding of two pyridine amide groups with two acid groups of diacids. In the solid phase, the ditopic receptor 1 shows a grid-like polymeric hydrogen-bonded network that changes to a polymeric wave-like 1:1 anti-perpendicular network instead of the syn–syn polymeric 1:1 (Goswami, S.; Dey, S.; Fun, H.-K.; Anjum, S.; Rahman, A.-U. Tetrahedron Lett. 2005, 46, 7187–7191), anti–anti polymeric 1:1 (Goswami, S.; Jana, S.; Dey, S.; Razak, I.A.; Fun, H.-K. Supramol. Chem. 2006 , 18, 571–574; Goswami, S.; Jana, S.; Fun, H.-K. Cryst. Eng. Comm. 2008, 10, 507–517; Goswami, S.; Jana, S.; Dey, S.; Sen, D.; Fun, H.-K.; Chantrapromma, S. Tetrahedron 2008, 64, 6426–6433), syn–syn 2:2 (Karle, I.L.; Ranganathan, D.; Haridas, V. J. Am. Chem. Soc. 1997 , 119, 2777–2783) or top–bottom-bound 1:1 (Garcia-Tellado, F.; Goswami, S.; Chang, S.K.; Geib, S.J.; Hamilton, A.D. J. Am. Chem. Soc. 1990 , 112, 7393–7394) co-crystals. 相似文献